The influence of pH on the rate of hydrolysis of acidic polysaccharides.
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Hydrogen-Ion Concentration↗
Biomedical subjects
B Larsen
Publications and source records attributed to B Larsen.
Studies on milk protein polymorphism in Danish cattle and the interaction of the controlling genes.
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Animals↗
Frequencies of alleles of the B-blood group system in Red Danish dairy cattle.
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Animals↗
High performance ion exclusion chromatographic characterization of the vaginal organic acids in women with bacterial vaginosis.
Vaginal organic acids have previously been detected by gas-liquid chromatography, but we have applied an ion exclusion high performance liquid chromatographic procedure to the analysis of vaginal discharge samples. This procedure has the advantage of not requiring derivitization of non-volatile acids and provides the convenience of a technique which does not require the use of flammable gasses, while allowing the identification of at least 18 different acids from the same chromatographic analysis. Vaginal discharge from women with symptoms of bacterial vaginosis was collected on weighed swabs and analysed for the presence of organic acids. The results were compared to the organic acid content of samples obtained from the same cohort of women after treatment with metronidazole. In addition, samples were obtained from asymptomatic women and these samples were analysed in the same manner. The number of organic acids present in samples from women with bacterial vaginosis was greater than the number found after treatment or among asymptomatic women. Succinic acid appeared to be inversely related to lactate concentration and succinate:lactate ratios were greater among women with bacterial vaginosis before treatment than after treatment. Liquid chromatography has proven useful as a means of evaluating the metabolic end-products of vaginal microorganisms in situ.
Acetates↗
Genistein effects on growth and cell cycle of Candida albicans.
Microbial virulence is generally considered to be multifactorial with infection resulting from the sum of several globally regulated virulence factors. Estrogen may serve as a signal for global virulence induction in Candida albicans. Nonsteroidal estrogens and estrogen receptor antagonists may therefore have interesting effects on yeast and their virulence factors. Growth of C. albicans was monitored by viable plate counts at timed intervals after inoculation into yeast nitrogen broth plus glucose. To determine if increased growth of yeast in the presence of estradiol was due to tyrosine kinase-mediated signaling, we measured growth in the presence of genistein, estradiol or genistein plus estradiol and compared these conditions to controls, which were not supplemented with either compound. Unexpectedly, genistein stimulated growth of C. albicans. In addition, genistein was found to increase the rate of germination (possibly reflecting release from G(0) into G(1) cell cycle phase) and also increased Hsp90 expression, demonstrated by a dot blot technique which employed a commercial primary antibody detected with chemiluminescence with horseradish peroxidase-labeled secondary antibody. These biological effects may be attributable to genistein's activity as a phytoestrogen. In contrast, nafoxidine suppressed growth of Candida and mildly diminished Hsp90 expression. This study raises the possibility of receptor cross-talk between estrogen and isoflavinoid compounds, and antiestrogens which may affect the same signaling system, though separate targets for each compound were not ruled out.
Candida albicans↗
Antagonistic effect of selenite on tumor promoter induced cell proliferation in cultures of rat tongue epithelium.
In cultures of rat tongue epithelial cells, cell proliferation following incubation with different doses of the potent tumor promoter TPA has been studied by using a stathmokinetic method counting colchicine arrested metaphases. It was demonstrated that 24 h incubation with concentrations higher than 5 ng TPA/mL medium caused inhibition, whereas below 5 ng TPA/mL medium caused stimulation of the mitotic activity reaching a maximum around 30 h from the start of the incubation period. Based on the evidence of the anticarcinogenic effect of selenium in several animal models, experiments have been performed elucidating the influence of an atoxic dose (1/1.000.000M) of selenite on the observed TPA-induced cell proliferation. Our results indicate that addition to the culture medium of an atoxic dose of selenite, not affecting the mitotic activity of control cultures, inhibits the TPA-induced stimulation of cell proliferation.
Animals↗
Estrogenic and CYP1A response of mummichogs and sunshine bass to sewage effluent.
Recent studies demonstrating feminization of effluent-exposed wild-caught male fish in the UK have prompted much research regarding the estrogenic activity of effluent from municipal sewage treatment plants (MSTPs). To investigate the estrogenicity and cytochrome P450 1A (CYP1A) induction potency of MSTP effluent, two species of fish, adult male mummichogs, Fundulus heteroclitus, and juvenile sunshine bass, Morone saxatilis x Morone chrysops, were exposed to un-chlorinated effluent (75% effluent, 25% seawater) from a large MSTP in Yonkers, NY, USA. After a 21-day static-daily (75%) renewal exposure, significant elevations over controls were observed in levels of vitellogenin (VtG) in plasma (1730%) and liver (131%) in effluent-exposed sunshine bass. In contrast, hepatic VtG was not elevated in mummichogs; plasma VtG was not measured in this species. Effluent exposure elevated hepatic CYP1A protein (140-145%) and ethoxyresorufin-O-deethylase (EROD) activity (408-598%) in both species. These findings suggest ontogenetic and/or species differences in response to estrogenic compounds in MSTP effluent. Furthermore, the elevation of CYP1A in response to sewage effluent exposure indicates the presence of additional compounds that may alter xenobiotic and/or steroid biotransformation in fish.
Animals↗
Effect of cortisol and urea on flavin monooxygenase activity and expression in rainbow trout, Oncorhynchus mykiss.
Expression of flavin-containing monooxygenase(s) (FMO) correlates with salinity exposure in certain species of euryhaline fish, such as the rainbow trout, Oncorhynchus mykiss. The mechanism(s) by which salinity regulates FMO is unclear. Adult rainbow trout were infused through the dorsal aorta with either cortisol or urea. At 500 ng/ml, cortisol caused a significant increase in FMO-catalyzed thiourea oxidase activity in gill and liver microsomes. FMOI expression, however, was significantly increased by the high cortisol dose only in gill microsomes. The levels of TMAO and urea were not altered by cortisol. In the liver, urea infusion caused an increase in hepatic FMO activity. FMO expression and activity correlated with elevated tissue urea levels, but TMAO concentrations were not related. These results indicate that FMO expression and activity may be partially controlled by the osmoregulatory/stress hormone. cortisol, and concentrations of the organic osmolyte, urea, in the rainbow trout.
Animals↗
Serum erythromycin levels in pregnancy.
Erythromycin is the recommended therapy for pregnant women with chlamydial infection. Despite the fact that this drug has been available since 1952, relatively little is known about its pharmacokinetic behavior in pregnant women, and no investigations have been conducted in women who were in the third trimester of pregnancy. In this study, 10 women were treated with erythromycin for chlamydial infection during pregnancy; 7 of these women were in the third trimester of pregnancy, and 3 were in the second trimester. Serum samples were obtained at 0.5, 1, 2, 3, and 4 hours after a 500-mg oral dose of erythromycin base and were analyzed to determine absorption and peak serum levels of erythromycin. Results indicated that absorption was delayed and serum levels were diminished in comparison with values reported in the literature for patients in the second trimester of pregnancy. In 2 women, erythromycin serum levels were not detectable at any time during the 4 hours of the study; these 2 women also experienced the most severe gastrointestinal symptoms. Although the size of our study population was small and certainly not definitive, the data suggest that in patients in the third trimester of pregnancy, severe adverse gastrointestinal events may forewarn of subtherapeutic plasma concentrations of erythromycin, which could have consequences for the treatment outcome.
Adolescent↗
Streptococcal puerperal sepsis and obstetric infections: a historical perspective.
The streptococcus, responsible for inestimable morbidity and mortality among parturient women since the 16th century, is no longer a significant cause of puerperal infection. Although the problem of the group A streptococcus in obstetrics has abated, the obstetrician is now confronted with the group B streptococcus, which is a major cause of fetal, neonatal, and maternal morbidity and mortality. Some historical insight into the infectious disease problems encountered by obstetric practitioners during the last four centuries allows comparison and contrast between the historic scourge of childbed fever and present day obstetric infections.
Anti-Bacterial Agents↗
Diagnostic considerations in intra-amniotic syphilis.
Amniotic fluid is rarely used in the evaluation of syphilis during pregnancy but was available from a woman with positive serologic tests in the 30th week of gestation. Nonmotile intra-amniotic spirochetes were seen by dark-field microscopy 20 hr after treatment with benzathine penicillin G. The identity of the organism in amniotic fluid was confirmed by immunofluorescent staining. Less than 0.5 units/ml of penicillin was present in the amniotic fluid at this time. The amniotic fluid was positive in the Venereal Disease Research Laboratory (VDRL; Atlanta, GA) test, and the concentration of IgM was elevated as was the ratio of lecithin to sphyngomyelin. Phosphatidyl inositol and phosphatidyl glycerol were also present in the amniotic fluid. After treatment the lecithin-sphyngomyelin ratio declined; phosphatidyl glycerol disappeared, whereas phosphatidyl inositol was still present. Despite evidence of intrauterine growth retardation at 30 weeks, the infant born at 37 weeks was of normal weight and length; however, the head circumference was below the tenth percentile. These studies suggest that analysis of amniotic fluid may provide new insights into the biology of syphilis in pregnancy, but does not constitute a recommendation for routine examination of the amniotic fluid in mothers with reactive serologic tests for syphilis.
Adult↗
C4*A6BQO: a 'new' C4 haplotype.
A C4 haplotype containing C4*A6 without C4*B1 is described. It occurred in the MHC haplotype HLA-A1, Cw5, Bw44, C2*1, BF*S, C4*A6BQO, DR3, GLO 2. This haplotype was observed in five of eight siblings, including the propositus who was in renal failure. The C4A6 was not haemolytically active and this new haplotype is therefore of particular interest since it is functionally equivalent to the rare C4-deficient haplotype C4*AQOBQO.
Alleles↗
Upstream stimulators for recoding.
Recent progress in elucidation of 5' stimulatory elements for translational recoding is reviewed. A 5' Shine-Dalgarno sequence increases both +1 and -1 frameshift efficiency in several genes; examples cited include the E. coli prfB gene encoding release factor 2 and the dnaX gene encoding the gamma and tau subunits of DNA polymerase III holoenzyme. The spacing between the Shine-Dalgarno sequence and the shift site is critical in both the +1 and -1 frameshift cassettes; however, the optimal spacing is quite different in the two cases. A frameshift in a mammalian chromosomal gene, ornithine decarboxylase antizyme, has recently been reported; 5' sequences have been shown to be vital for this frameshift event. Escherichia coli bacteriophage T4 gene 60 encodes a subunit of its type II DNA topoisomerase. The mature gene 60 mRNA contains an internal 50 nucleotide region that appears to be bypassed during translation. A 16 amino acid domain of the nascent peptide is necessary for this bypass to occur.
Animals↗
Accuracy of auscultatory blood pressure measurements in hypertensive and obese subjects.
In 59 treated or untreated hypertensive subjects and 52 obese subjects (normotensive or hypertensive), intraarterial blood pressure (BP) was compared to simultaneous auscultatory measurements. In the hypertensive group, arm circumference was less than 35 cm compared to over 35 cm in the obese subjects. The occluding cuffs were 12 x 35 cm and 15 x 43 cm respectively. Mean difference between auscultatory and intraarterial systolic BP (SBP) was among the hypertensive -- 8.8 mm Hg (SDDIFF 9.0 mm Hg, range + 13/ - 28) and among the obese - 3.1 mm Hg (SDDIFF 13.8 mm Hg, range + 19/ - 49). Mean difference auscultatory-intraarterial diastolic BP (DBP) Phase V was among the hypertensive patients + 10.8 mm Hg (SDDIFF 6.8 mm Hg, range + 29/ - 8), and among the obese + 5.5 mm Hg (SDDIFF 7.3 mm Hg, range + 20/ - 10). Thus, a 15 x 43 cm cuff used in obese subjects with an arm circumference exceeding 35 cm gave quite as reliable measurements as a 12 x 35 cm cuff used in hypertensive subjects with "normal" dimension of the upper arm (less than 35 cm). It is emphasized that there is a wide scatter in the interindividual differences, and it is argued that a comparison between auscultatory and intraarterial BP should be performed in patients with poorly controlled hypertension.
Adult↗
Focal cerebral hyperemia in acute stroke. Incidence, pathophysiology and clinical significance.
In a consecutive study comprising 41 patients with completed stroke of less than 72 hours duration, cerebral angiography and measurements of the regional cerebral blood flow (rCBF) were performed within 24 hours after admission. The rCBF study was done using the 133-Xenon intracarotid injection method and a 254 multi-detector camera. CT scan was done 24 hours after the rCBF study. Focal cerebral hyperemia was found in 16 patients. The study revealed 3 different types of hyperemia: Border-zone hyperemia, surrounding ischemic areas, was seen in patients with occluded arteries on angiography, presumably resulting from accumulation of acid metabolites in the border-zone of acute infarcts. Postischemic hyperemia was seen in patients without occlusion, presumably due to recanalization of a prior occluded artery. Remote hyperemia was found distant from the infarcted area, presumably due to local tissue pressure on brain tissue. Cortical infarcts (10 patients) all had extensive hyperemic areas. Because the 254 detector camera has an excellent resolution in the cortical surface, our findings strongly suggest that all acute cerebral infarcts are, in fact, associated with hyperemic areas. The hyperemic areas are often extensive and vascular reactivity is commonly impaired. It is suggested that treatment aimed at reducing blood flow in hyperemic areas might improve prognosis.
Aged↗
Focal cerebral ischemia measured by the intra-arterial 133xenon method. Limitations of 2-dimensional blood flow measurements.
The limitations of 2-dimensional isotope techniques in the study of focal cerebral ischemia were investigated using the intra-carotid 133 xenon injection method and a 254 multidetector scintillation camera. To make sure that the detectors "look" directly on infarcted areas, only patients with infarcts involving cortical surface structures were included in the study. Eleven such patients were found among 43 consecutive patients with completed stroke, all investigated with CT-scan. The blood supply to the infarcted areas was evaluated using 3 different approaches: 1) The first minute washout of 133 xenon (rCBF), 2) the initial distribution of isotope during the first 5 sec and 3) the cumulated counts recorded during 15 min. Compton scatter and the "look through phenomenon" were responsible for the majority of counts recorded from the infarcted areas and the blood flow recorded was found to be grossly overestimated and much more influenced by the blood flow in the surroundings than in the ischemic area itself. However, using the 3 approaches, infarcted areas were always disclosed by our equipment. It is concluded that 2-dimensional isotope technique is not reliable for quantifying focal ischemic lesions. The method should be limited to the qualitative demonstration of the ischemic lesions for which it is fully reliable.
Brain Ischemia↗
Blood flow and vascular reactivity in collaterally perfused brain tissue. Evidence of an ischemic penumbra in patients with acute stroke.
In a group of 48 patients with completed stroke, 8 patients had viable collaterally perfused brain tissue which was accessible for rCBF recordings with a two dimensional technique. All 8 had deep subcortical infarcts on CT-scan, and angiographic occlusion of the arteries normally supplying the infarcted territory. The brain tissue overlying the deep infarcts appeared normal on CT-scan and was supplied by collateral circulation. rCBF was measured in all within 72 hours after the stroke. The intra-carotid Xe-133 injection method and a 254 multidetector camera were used to study rCBF. Relatively ischemic low flow areas were a constant finding in the collaterally perfused tissue. In 6 of the patients, the collaterally perfused part of the brain had low flow values comparable to those of an "ischemic penumbra" (viable, but functionally depressed brain tissue due to inadequate perfusion). Autoregulation was impaired in all of the collaterally perfused areas while the CO2-response always was preserved. Steal phenomena were not seen. In the surrounding brain tissue, autoregulation was normal in 5 patients and impaired in 3 while the CO2-response seemed to be normal. The results confirm the experimental finding of an ischemic penumbra associated with acute cerebral infarcts and suggest that early restoration of the blood flow in acute stroke patients might improve recovery and prognosis in selected patients.
Acute Disease↗
Chronically impaired autoregulation of cerebral blood flow in long-term diabetics.
Using the arteriovenous oxygen difference method autoregulation of cerebral blood flow (CBF) was tested in 16 long-term diabetics and eight control patients. Blood pressure was raised by angiotensin infusion and lowered by trimethaphan camsylate infusion, in some cases combined with head-up tilting of the patient. Regression analysis was carried out on the results in order to quantify autoregulatory capacity. In the control patients CBF did not vary with moderate blood pressure variations, indicating normal autoregulation. In four of the 16 diabetic patients CBF showed significant pressure dependency, indicating impaired autoregulation. The cause of impaired autoregulation in some long-term diabetics is believed to be diffuse or multifocal dysfunction of cerebral arterioles due to diabetic vascular disease. Other conditions with impaired autoregulation are discussed and compared with that seen in long-term diabetes.
Adult↗