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Notes: Abstract PURPOSE: Obstetric trauma and excessive defecatory straining with perineal descent may lead to pudendal neuropathy with bilateral increase in pudendal nerve terminal motor latencies (PNTML). We have frequently observed unilateral prolongation of PNTML. Diagnostic and therapeutic implications of unilateral pudendal neuropathy are discussed. METHODS: Records of 174 patients referred to pelvic floor laboratory for anorectal manometry and PNTML testing were reviewed. Computerized anal manometry was performed using dynamic pressure analysis, and PNTML was determined using a pudendal (St. Mark's) electrode. RESULTS: No response was elicited from pudendal nerves to electric stimulation from both sides in 14 patients (8 percent) and from one side in 24 patients (13.8 percent). Bilateral PNTML determination was possible in only 136 patients (78 percent), of whom 83 patients (61 percent) had no evidence of neuropathy, revealing normal PNTML on both sides. Of 53 patients (39 percent) with delayed conduction in pudendal nerves, in 15 patients (28 percent), PNTML was abnormally prolonged on both sides, with an abnormal mean value for PNTML. In the remaining 38 patients (72 percent), PNTML was abnormal on one side: in 27 patients with an abnormal mean PNTML and in 11 patients with a normal mean PNTML. CONCLUSIONS: A significant number of patients with pelvic floor disorders have only unilateral pudendal neuropathy. Patients with unilaterally prolonged PNTML should be considered to have pudendal neuropathy, despite normal value for mean PNTML. This fact may be relevant in planning surgical treatment and in predicting prognosis of patients with sphincter injuries.

Notes: Abstract PURPOSE: Denervation of the extrinsic anal sphincter and pudendal neuropathy are confirmed by electrophysiologic or electromyographic testing, techniques that may not be available universally and require special equipment and training. A simple manometric test that is easy to perform and complements existing studies was performed to confirm pudendal neuropathy. METHODS: Fourteen patients with excessive defecatory straining and 30 patients with idiopathic fecal incontinence were studied by electrophysiology and balloon reflex manometry. Pudendal nerve terminal motor latency (PNTML) and rectoanal excitatory reflex were evaluated for abnormalities. Results were compared with 20 controls who had no anorectal complaints and who had similar testing performed. RESULTS: In controls, PNTML was normal in all but one person. Rectoanal excitatory reflex could be elicited in all controls with either 20 or 40 ml of air. Four different types of balloon reflex responses were observed in patient groups: diminutive excitation, delayed excitation, excitation at high volume of distention only, and absent excitation. Ten patients with fecal incontinence had normal PNTML but abnormal distal excitatory reflex, 5 patients had abnormal PNTML but normal distal excitatory reflex, and 15 patients had both PNTML and excitatory reflex that were abnormal. In patients with excessive defecatory straining, results of both tests were abnormal in six patients, and eight patients had abnormal excitatory reflex but normal PNTML. CONCLUSION: Pudendal neuropathy may result in abnormalities of excitatory reflex morphology or other characteristics. Abnormal distal excitatory reflex may complement electrophysiologic findings or may serve as a suitable alternative to confirm pudendal neuropathy in centers where facilities for formal testing are not available.

Notes: Abstract PURPOSE: Fecal incontinence may occur in several forms. Although some patients are grossly incontinent, other patients experience only leakage. In patients with gross incontinence, severity can range from the mildest forms (limited to loss of control of flatus) to the most severe forms (involving loss of solid stool). This study was undertaken to determine which physiologic parameters differentiate female patients with incontinence of solid stool from patients with control of formed stool and incontinence limited to seepage. METHODS: Thirty-eight consecutive female patients with a primary complaint of seepage or solid stool incontinence were evaluated using water perfusion manometry, balloon inflation assessment of rectal sensitivity, and pudendal nerve terminal motor latency. A prospectively maintained database was used for collection of data. The findings in the two patient groups were compared with patients in a group of normal control individuals. Ages of the women in the three groups were similar. RESULTS: Both groups of patients demonstrated statistically significant ( P 〈 0.05) decreases in rest and squeeze sphincter lengths, pressures, and pressure volumes compared with normal volunteers. The patients also had significantly more asymmetric high-pressure zones and hypersensitive rectums. No significant difference between the two groups of incontinent patients could be identified using any of these parameters. Significant differences between the groups were found in pudendal nerve function. The distal rectoanal excitatory reflex was abnormal in 58.1 percent of grossly incontinent women compared with 28.6 percent of patients with leakage ( P 〈 0.05). The majority of patients with leakage alone (65 percent) had normal pudendal nerve terminal motor latency, whereas only 22.6 percent of women with gross fecal incontinence had normal pudendal nerve terminal motor latency bilaterally ( P =0.01). CONCLUSIONS: Normal bilateral pudendal nerve function can partially compensate for abnormal sphincter symmetry and function, permitting women with grossly abnormal parameters to maintain control of bowel movements. It remains to be seen whether, with advancing age, patients with leakage will have development of slowed pudendal nerve conduction and, if so, whether their condition will progress to gross incontinence.

Notes: Abstract PURPOSE: This study was undertaken to determine the role of abnormal distal rectoanal excitatory reflex (RAER) as a marker of pudendal neuropathy and to compare results with pudendal nerve terminal motor latency (PNTML) and single fiber density (SFD) estimation. METHODS: Fifteen female patients (mean age, 47.1 (range, 20–70) years) referred to the pelvic floor laboratory with pelvic floor disorders (fecal incontinence, 13 patients; constipation, 2 patients) were evaluated prospectively with neurophysiologic tests and balloon reflex manometry for evidence of pudendal neuropathy. RESULTS: Pudendal nerve terminal motor latency provided evidence of pudendal neuropathy in ten patients (67 percent) and was normal in five patients (33 percent). Increased SFD confirmed denervation of the external anal sphincter in 12 patients (80 percent), being normal in 3 patients (20 percent). Distal RAER was abnormal in 13 patients (87 percent) and was normal in 2 patients (13 percent). In ten patients (67 percent), the three diagnostic modalities were in complete agreement, correctly identifying neuropathy in nine patients (60 percent) and excluding nerve damage in one patient (7 percent). Distal RAER was normal despite prolonged PNTML and increased SFD in one patient (7 percent). In two patients (13 percent), distal RAER was abnormal or absent despite normal PNTML and SFD. Pudendal nerve terminal motor latency was normal in the presence of abnormal distal RAER and increased SFD on electromyography in two patients (13 percent). CONCLUSIONS: Abnormal distal RAER compares favorably with current neurophysiologic tests used to diagnose pudendal neuropathy.

Notes: Abstract Heterozygous plants of barley (Hordeum vulgare L. cv. Maris Mink) with activities of chloroplastic glutamine synthetase (GS) between 47‰ and 97‰ of the wild-type and ferredoxin-dependent glutamate synthase (Fd-GOGAT) activities down to 63‰ of the wild-type have been used to study the control of photosynthetic fluxes. Rates of CO2 assimilation measured over a range of intercellular CO2 concentrations and photon flux densities (PFDs) were little different in the wild-type and a mutant with 47‰ GS, although total activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) decreased by about 20‰ with a decrease in GS to 50‰ of the wild-type. The quantum efficiencies of photosystem II electron transport (ΦPSII and CO2 assimilation ΦCO2) were determined. ΦPSII was lower than expected in mutants with 50‰ less GS under conditions which enhance the photorespiratory flux, but were identical to the wild-type under non-photorespiratory conditions, suggesting that at high rates of photorespiration the electron requirement for net CO2 assimilation declines in plants with decreased GS. This discrepancy in the electron requirement between the wild-type and the 47‰ GS mutant was enhanced at high temperatures and low CO2, conditions which favour oxygenation by Rubisco. Photochemical and non-photochemical chlorophyll a fluorescence quenching as well as the quantum efficiency of excitation-energy capture by open photosystem II reaction centres were differentially affected in mutants with less GS relative to the wild-type when CO2 was lowered or the PFD was varied. The quantum efficiencies of electron transport in photosystems I and II were closely correlated under a range of PFDs and CO2 concentrations, confirming that the rate of linear electron transport was much lower in plants with less GS. It is shown that GS exerts considerable control (flux control coefficients between 0.5 and 1.0) on the electron requirement for CO2 assimilation at high fluxes of photorespiration relative to CO2 assimilation. Apart from the control of GS on protein and Rubisco contents, GS in the wild-type has also some direct positive control on CO2 assimilation. However, negative control on CO2 assimilation was found in mutants with 50‰ less GS. These data, taken with the data on electron requirements for CO2 assimilation, suggest that CO2-fixing processes other than that catalysed by Rubisco, such as carboxylation of phosphoenolpyruvate, or an inhibition of photorespiration (e.g. glycine decarboxylation), may contribute to the observed CO2 exchange and photosystem II electron transport in plants with less GS. In the 63‰-Fd-GOGAT mutant, rates of CO2 assimilation were appreciably lower than in the wild-type under a range of PFDs and CO2 concentrations, which largely reflected lower contents of Rubisco in the Fd-GOGAT mutants. Assimilation of CO2 was inhibited appreciably at high CO2 concentrations. There was little difference in the electron requirement for CO2 assimilation between the wild-type and mutants with less Fd-GOGAT, although there were indications that a triose-phosphate/glycerate-3-phosphate shuttle or cyclic electron transport operates to balance ATP generation and NADP reduction. The latter was supported by a curvilinear relationship of photosystem I and II electron transport in the 63‰ Fd-GOGAT mutant. A positive control is exerted by Fd-GOGAT on the amounts of protein and Rubisco and on CO2 assimilation.

Notes: Abstract. A mutant (LaPr 87/30) of barley (Hordeum vulgare L.) deficient in glycine decarboxylase (GDC; EC 2.1.2.10) was crossed with wild-type plants to generate heterozygous plants with reduced GDC activities. Plants of the F2 generation were grown in air and analysed for reductions in GDC proteins and GDC activity. The leaves of heterozygous plants contained reduced amounts of H-protein, and when the content of H-protein was lower than 60% of the wild-type, the P-protein was also reduced. The contents of the other two proteins of the GDC complex, T-protein and L-protein were not affected. Glycine decarboxylase activities, measured as the decarboxylation of [1-14C]glycine by intact mitochondria released from protoplasts, were between 47% and 63% of the wild-type activity in heterozygous plants and between 86% and 100% in plants with normal contents of H-protein. The enzyme activity was linearly correlated with the relative content of H-protein. Plants with reduced GDC activities developed normally and did not show major pleiotropic effects. In air, the reduction in GDC activity had no effect on the leaf metabolite content or photosynthesis, but under conditions of enhanced photorespiration (low CO2 and high light), glycine accumulated and the rates of photosynthesis decreased compared to the wild-type. The accumulation of glycine did not lead to a depletion of amino donors or to the accumulation of glyoxylate. The lower rates of photosynthesis were probably caused by an impaired recycling of carbon in the photorespiratory pathway. It is concluded that GDC has no control over CO2 assimilation under normal growth conditions, but appreciable control by GDC becomes apparent under conditions leading to higher rates of photorespiration.

Notes: Abstract Heterozygous mutants of barley (Hordeum vulgare L. cv. Maris Mink) with decreased activities of chloroplastic glutamine synthetase (GS) between 97 and 47% of the wild type and ferredoxin dependent glutamate synthase (Fd-GOGAT) down to 64% of the wild type have been used to study aspects of glyoxylate metabolism and the effect of glyoxylate on the activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in vivo. In the leaf, the extractable activities of serine:glyoxylate aminotransferase decreased with a decrease in GS whereas activities of glutamate and alanine:glyoxylate aminotransferase increased, pointing to a re direction of amino donors from serine to glutamate and alanine. Under ambient conditions, the leaf contents of glutamate and alanine declined continuously with a decrease in GS, in parallel with the decrease in total amino acids. Glycine, serine and asparagine contents decreased with a decrease in GS to approximately 70% of the wild type, but increased again with a further decrease in GS. At high irradiances and at low CO2 concentrations, glyoxylate contents exhibited a pronounced minimum between 60% and 80% GS. With a further decrease in GS, glyoxylate contents recovered and approached values similar to the wild type. The activation state of Rubisco showed a negative correlation with glyoxylate contents, indicating that a decrease in GS feeds back on the first step of carbon assimilation and photorespiration. The activation state of stromal fructose-1,6-bisphosphatase was unaffected by a decrease in GS or Fd-GOGAT, whereas the activation state of NADP dependent malate dehydrogenase changed in a complex manner. The CO2photocompensation point, Γ*, was appreciably increased in mutants with 47% GS. ‘Mitochondrial respiration’ in the light (Rd) was reduced with a decrease in GS. Relative rates of CO2 release into CO2-free air between the wild type and the 47%-GS mutant correlated with determinations of Γ*. These data are consistent with the view that when GS is decreased there is an increased oxidative decarboxylation of glyoxylate resulting from a decreased availability of amino donors for the transamination of glyoxylate to glycine, and that when GS activities are lower than 70% of the wild type an additional mechanism operates to reduce the photorespiratory loss of ammonia.

Notes: Abstract Wild-type and mutant plants of barley (Hordeum vulgare L. cv. Maris Mink) lacking activities of chloroplastic glutamine synthetase (GS) and of ferredox-in-dependent glutamate synthase (Fd-GOGAT) were crossed to generate heterozygous plants. Crosses of the F2 generation containing GS activities between 47‰ and 97‰ of the wild-type and Fd-GOGAT activities down to 63‰ of the wild-type have been selected to study the control of both enzymes on photorespiratory carbon and nitrogen metabolism. There were no major pleiotropic effects. Decreased GS had a small impact on leaf protein and the total activity of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco). The activation state of Rubisco was unaffected in air, but a decrease in GS influenced the activation state of Rubisco in low CO2. In illuminated leaves, the amino-acid content decreased with decreasing GS, while the content of ammonium rose, showing that even small reductions in GS limit ammonium re-assimilation and may bring about a loss of nitrogen from the plants, and hence a reduction in protein and Rubisco. Leaf amino-acid contents were restored, and ammonium and nitrate contents decreased, by leaving plants in the dark for 24 h. The ratios of serine to glycine decreased with a decrease in GS when plants were kept at moderate photon flux densities in air, suggesting a possible feedback on glycine decarboxylation. This effect was absent in high light and low CO2. Under these conditions ammonium contents exhibited an optimum and amino-acid contents a minimum at a GS activity of 65‰ of the wild-type, suggesting an inhibition of ammonium release in mutants with less than 65‰ GS. The leaf contents of glutamate, glutamine, aspartate, asparagine, and alanine largely followed changes in the total amino-acid contents determined under different environmental conditions. Decreased Fd-GOGAT resulted in a decrease in leaf protein, chlorophyll, Rubisco and nitrate contents. Chlorophyll a/b ratios and specific leaf fresh weight were lower than in the wild-type. Leaf ammonium contents were similar to the wild-type and total leaf amino-acid contents were only affected in low CO2 at high photon flux densities, but mutants with decreased Fd-GOGAT accumulated glutamine and contained less glutamate.

Notes: Abstract. Glycine-accumulating mutants of barley (Hordeum vulgare L.) and Amaranthus edulis (Speg.), which lack the ability to decarboxylate glycine by glycine decarboxylase (GDC; EC 2.1.2.10), were used to study the significance of an alternative photorespiratory pathway of serine formation. In the normal photorespiratory pathway, 5,10-methylenetetrahydrofolate is formed in the reaction catalysed by GDC and transferred to serine by serine hydroxymethyltransferase. In an alternative pathway, glyoxylate could be decarboxylated to formate and formate could be converted into 5,10-methylenetetrahydrofolate in the C1-tetrahydrofolate synthase pathway. In contrast to wild-type plants, the mutants showed a light-dependent accumulation of glyoxylate and formate, which was suppressed by elevated (0.7%) CO2 concentrations. After growth in air, the activity and amount of 10-formyltetrahydrofolate synthetase (FTHF synthetase; EC 6.3.4.4), the first enzyme of the conversion of formate into 5,10-methylenetetrahydrofolate, were increased in the mutants compared to the wild types. A similar increase in FTHF synthetase could be induced by incubating leaves of wild-type plants with glycine under illumination, but not in the dark. Experiments with 14C showed that the barley mutants incorporated [14C]formate and [2-14C]glycollate into serine. Together, the accumulation of glyoxylate and formate under photorespiratory conditions, the increase in FTHF synthetase and the ability to utilise formate and glycollate for the formation of serine indicate that the mutants are able partially to compensate for the lack of GDC activity by bypassing the normal photorespiratory pathway.

Notes: Abstract The aim of this work was to examine the effect of abrupt changes in temperature in the range 5 to 30°C upon the rate of photosynthetic carbon assimilation in leaves of barley (Hordeum vulgare L.). Measurement of the CO2-assimilation rate in relation to the intercellular partial pressure of CO2 at different temperatures and O2 concentrations and at saturating irradiance showed that as the temperature was decreased photosynthesis was saturated at progressively lower CO2 partial pressures and that the transition between the CO2-limited and ribulose-1,5-bisphosphate-regeneration-limited rate became more abrupt. Feeding of orthophosphate to leaves resulted in an increased rate of CO2 assimilation at lower temperatures at around ambient or higher CO2 partial pressures both in 20% O2 and in 2% O2 and it removed the abruptness in the transition between the CO2-limited and ribulose-1,5-bisphosphate-regeneration-limited rates. Phosphate feeding tended to inhibit carbon assimilation at higher temperatures. The response of carbon assimilation to temperature was altered by feeding orthophosphate, by changing the concentrations of CO2 or of O2 or by leaving plants in the dark at 4°C for several hours. Similarly, the response of carbon assimilation to phosphate feeding or to changes in 2% O2 was altered by leaving the plants in the dark at 4°C. The mechanism of limitation of photosynthesis by an abrupt lowering of temperature is discussed in the light of the results.