Design of a system for the control of low dissolved oxygen concentrations: critical oxygen concentrations for Azotobacter vinelandii and Escherichia coli

The physiological activity of microorganisms in environments with low dissolved oxygen concentrations often differs from the metabolic activity of the same cells growing under fully aerobic or anaerobic conditions. This article describes a laboratory-scale system for the control of dissolved oxygen at low levels while maintaining other parameters, such as agitator speed, gas flowrate, position of sparger outlet, and temperature at fixed values. Thus, it is possible to attribute in dilute nonviscous fermentations all physiologic changes solely to changes in dissolved oxygen. Experiments were conducted with Azotobacter vinelandii and Escherichia coli. Critical oxygen concentrations for growth (that value of oxygen allowing growth at 97% of mu max) were measured as 0.35 +/- 0.03 mg/L for A. vinelandii and 0.12 +/- 0.03 mg/L for E. coli. These values are significantly different from the commonly quoted values for critical oxygen concentrations based on respiration rates. Because of the superior dissolved oxygen control system and an improved experimental protocol preventing CO2 limitation, we believe that the values reported in this work more closely represent reality.

Etiologic studies of the 1983 and 1984 outbreaks of epidemic diarrhea in Guangxi

Studies are reported on two outbreaks of epidemic diarrhea in China involving 19,007 patients. The first outbreak occurred in the northern part of the Guangxi Autonomous Region and extended south from April through September 1983. In June 1984 a second outbreak of 6,570 cases occurred in Guanyang, a county in the northern part of Guangxi. 125 fecal samples from the two outbreaks were cultured for bacteria; all of the samples except one were negative. Rotavirus particles were detected in 44.1% (15/34) of stool specimens examined by immune electron microscopy. The two outbreaks appeared to be caused by non-group-A rotaviruses, based on the pattern of electrophoretic migration of the RNA genome segments in polyacrylamide gels and on the lack of a detectable common group antigen(s) when tested by an enzyme-linked immunosorbent assay for group A rotaviruses. Complement-fixation tests also indicated that 37.5% of convalescent-phase sera from patients produced antibody to the isolated rotavirus. The total molecular weight of the RNA segments in the new Guangxi strain was calculated to be 10.69 X 10(6), with the 11 genome segments having molecular weights (X 10(6)) of 2.19, 1.83, 1.56, 1.53, 0.82, 0.81, 0.60, 0.46, 0.35, 0.30, and 0.24. This study also reports comparative detection rates for direct and immune electron microscopy and for PAGE. PAGE proved to be the most sensitive detection method for these new rotaviruses.

Effect of norepinephrine on inhibition of mouse brain (Na+ + K+)-stimulated, (Mg++)-dependent, and (Ca++)-dependent ATPase activities by ethanol

Norepinephrine (0.1 mM) has been reported to "sensitize" (Na+ + K+)-ATPase activity of rat brain homogenates to inhibition by ethanol. The present study extends these investigations to the mouse and includes other ATPase activities. We measured the effects of norepinephrine on the sensitivity of ethanol-induced inhibition of (Na+ + K+)-stimulated (E.C. 3.6.1.3), (Mg++)-dependent (E.C. 3.6.1.4) and (Ca++)-dependent ATPase activities. Whole forebrains from C57BL/6J mice were homogenized and assayed in vitro for ATPase activity using standard conditions. Ethanol (0.125-2.0 M) caused a dose-dependent inhibition of all three ATPases. Norepinephrine (0.1 mM) had no appreciable effect on ethanol's inhibition of (Na+ + K+)-stimulated or (Ca++)-dependent ATPase activities, but slightly antagonized ethanol's effect on (Mg++)-ATPase. These results suggest that norepinephrine has little effect on the sensitivities of specific ATPases to ethanol inhibition in mouse brain.

Studies on the reactogenicity and immunogenicity of the BRD-2 and RA27/3 live attenuated rubella vaccines

A study to compare the reactogenicity and immunogenicity of the BRD-2 and RA27/3 rubella vaccine strains was conducted in GuangXi, China in 1982. Ninety eight susceptible children between two and six years of age, with haemagglutination inhibition (HI) antibody titres of less than 10, were inoculated with RA27/3 vaccine strain. A similar group of 103 children were inoculated with BRD-2 vaccine strain; 110 uninoculated children served as a control group. The percentages of children who had fever reactions were 30.09% for RA27/3, 20.04% for BRD-2, and 24.50% for the uninoculated group. Neither vaccine evoked a high fever reaction. For both vaccines, the seroconversion rates estimated 42 days after immunization were 100%. The geometric mean titre of HI antibody was 144.4 +/- 2.04 for recipients of RA27/3, and 116.1 +/- 2.0 for those vaccinated with BRD-2. The rate of excretion of virus from the nose and throat was 26.67% for the recipients of RA27/3 and 23.08% for those who received BRD-2. No vaccine virus was isolated from the uninoculated susceptibles who were in close contact with the vaccinated children. Furthermore, the latter group remained seronegative when tested after 42 days of contact with the vaccinated. Hence, it appears that both RA27/3 and BRD-2 vaccine viruses have no capacity for being transmitted to unvaccinated contacts. In susceptible adolescents immunized with the BRD-2 vaccine viruses have no capacity for being transmitted to unvaccinated contacts. In susceptible adolescents immunized with the BRD-2 vaccine strain, a mild febrile reaction was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma mevalonate as a measure of cholesterol synthesis in man

Measurement of mevalonic acid (MVA) concentrations in plasma or 24-h urine samples is shown to be useful in studies of the regulation of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and cholesterol synthesis. Plasma MVA concentrations, measured either at 7-9 a.m. after an overnight fast, or throughout the 24-h cycle, were compared with cholesterol synthesis rates that were measured by the sterol balance method: plasma MVA concentrations were directly related to the rate of whole body cholesterol synthesis (r = 0.972; p less than 0.001; n = 18) over a tenfold range of cholesterol synthesis rates. Moreover, hourly examination of MVA concentrations throughout the day demonstrated that interventions such as fasting or cholesterol feeding cause suppression of the postmidnight diurnal rise in plasma MVA concentrations, with little change in the base-line of the rhythm. Thus, the daily rise and fall of plasma MVA appears to reflect changes in tissues and organs, such as the liver and intestine, that are known to be most sensitive to regulation by fasting or by dietary cholesterol. The hypothesis that short-term regulation of HMG-CoA reductase in tissues is quickly reflected by corresponding variations in plasma MVA was tested by using a specific inhibitor of HMG-CoA reductase, mevinolin, to block MVA synthesis. Mevinolin caused a dose-dependent lowering of plasma MVA after a single dose; and in patients who received the drug twice a day for 4 wk, it decreased 24-h urinary MVA output. Significant lowering of plasma cholesterol was achieved through administration of mevinolin at doses that only moderately limit MVA production.

Biochemical mechanisms on species differences in gastric carcinogenesis

The biochemical denitrosation of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in tissues from four strains of rat, inbred Buffalo, Lewis, B-N, and the random-bred Sprague-Dawley, with different sensitivities to MNNG-induced gastric carcinomas was investigated as a possible explanation for the species/strain differences in MNNG-induced carcinogenesis. An analytical HPLC method was developed to assay denitrosation of MNNG to N-methyl-N'-nitroguanidine (MNG) by cytosolic, microsomal, mitochondrial, and nuclear cell fractions. All the activity was contained in the microsomal and cytosolic fractions, with the major portion occurring in the cytosol. The activity in both fractions was NADPH-dependent, but denitrosation was not reduced by inhibitors of the cytochrome P-450 system. Denitrosation of MNNG post-mitochondrial supernatant (S9) fractions from liver, glandular stomach mucosa, and duodenal mucosa of the four rat strains was determined. In all strains, denitrosation activities were highest in liver. Comparisons between the three strains most sensitive to MNNG-induced gastric carcinogenesis indicated no large differences for any tissue. However, Buffalo, the most resistant strain, did have a higher level of denitrosating activity in all three tissues, which is consistent with the hypothesis that higher levels of detoxifying enzymes may lead to a decreased incidence of tumors. On the other hand, denitrosation accounts for less than 3% of the MNNG that disappears during the incubation period so that the relevance of denitrosation as a mechanism in strain-specific sensitivity to MNNG-induced gastric carcinoma requires additional studies.

Differentiation of myoblast cell lines and biological methylation: 3-deazaadenosine stimulates formation of multinucleated myofibers

Treatment of myoblast cell lines with 3-deazaadenosine stimulates differentiation into myofibers. Myoblast clone L5/ 3B5 , which does not form myofibers after 6 days in fusion medium, was stimulated to form myofibers after 5 days of culture in fusion medium containing 50 microM 3-deazaadenosine. Myoblast clone L5/ 3C4 , which normally begins to form myofibers after 4 days in fusion medium, was stimulated by 50 microM 3-deazaadenosine to form myofibers after 3 days in culture and the extent of fusion was also increased. In the presence of 100 microM homocysteine thiolactone, the concentration of 3-deazaadenosine that stimulated maximal fusion was reduced by a factor of 10, from 50 microM to 5 microM 3-deazaadenosine. Stimulation of myofiber formation by 3-deazaadenosine suggests a requirement for one or more methylation reactions in myoblast differentiation and the potentiation by homocysteine thiolactone indicates that myofiber formation is specifically stimulated by an intracellular accumulation of 3-deazaadenosylhomocysteine.

A study of a Caucasian family with variant von Willebrand's disease in association with vascular telangiectasia and haemoglobinopathy

A family was identified which carries multi-haematological disorders including Type IIA von Willebrand's disease, vascular telangiectasia, and a haemoglobinopathy (haemoglobin S trait). In the affected individuals, the von Willebrand's disease varies in its expression from an asymptomatic form to a severe form especially in those patients with telangiectasia. Some patients have vascular telangiectasia in the mucous membranes of the mouth and lips. In two patients endoscopy disclosed telangiectasia in the mucous membranes of the gastrointestinal tract. All of the patients who had telangiectasia also had von Willebrand's disease. An incidental finding was the presence of an abnormal haemoglobin (haemoglobin S) in some family members. The pattern of inheritance of the haemoglobinopathy was unrelated to the inheritance pattern of von Willebrand's disease. The presence of haemoglobin S did not interfere with the aggregation of platelets in response to ristocetin.

Aerosol lead and associated elements in Beijing, China

The relative importance of local and regional sources of lead and associated elements in fine and coarse aerosol particles of an urban atmosphere was assessed by means of a two-day study, July 20 and 30, 1980 in Beijing, China. Five near-ground locations were selected for aerosol sampling by cascade impactors and elemental analysis by proton induced X-ray emission (PIXE): the imperial palace courtyard, a park, near two streets, and a mid-street traffic island. These sites, ranked in order of increasing traffic intensity and fugitive surface dust, showed that concentrations of major dust constitutents, represented by coarse particle (>2 μm diameter) Si, Al, and Ca, increased correspondingly. Pb, as well as Zn, As, and Cu, were present mainly in fine (<2 μm) particles; their concentrations were unrelated to traffic, indicating they resulted mainly from regional combustion or other sources. However, these elements also were present in coarse particles at concentrations that varied with the major dust elements and were relatively enriched, compared to average earth crust rock material, by factors of more than 100 (Pb), 50 (Zn), and 10 (Cu). Nonurban Beijing shows much smaller coarse aerosol enrichments of Pb, Zn, and Cu, indicating urban contamination of surface dust. Published data from St. Louis, USA show both fine and coarse aerosol Pb and Zn. Compared with Beijing, fine and coarse concentrations in St. Louis are similar for Pb, but lower for Zn, Ca, and Fe. Both Pb and Zn are enriched relative to earth crust composition to a greater degree in St. Louis than Beijing in both fine and coarse particle size ranges. The results suggest that heavy metals from combustion occur in the air as fine particles and, after deposition on the surface, as reentrained coarse particles of fugitive dust. Both many contribute to human exposures of these heavy metals.

Carbamazepine diminishes the sensitivity of the plasma arginine vasopressin response to osmotic stimulation

Carbamazepine, a drug used to treat manic-depressive illness, has been reported to possess antidiuretic properties, but its effects on arginine vasopressin (AVP) secretion are controversial. Consequently, we examined plasma AVP secretion during hypertonic (5%) saline infusion in seven manic-depressive patients while on placebo and after 3-5 weeks of carbamazepine treatment. We also measured carbamazepine's effects on basal levels of the hormone in cerebrospinal fluid. Carbamazepine significantly reduced the sensitivity of the plasma AVP response to osmotic stimulation without affecting the osmotic threshold for AVP secretion. Moreover, carbamazepine did not affect baseline weight, plasma osmolality, plasma sodium, urine output, plasma AVP, or cerebrospinal fluid AVP. Although the functional significance of these findings remain to be fully determined, the fact that carbamazepine significantly reduced AVP secretion without inducing diuresis supports previous suggestions that carbamazepine enhances renal responsivity to available AVP. In addition, since carbamazepine failed to affect the osmotic threshold, the reported cases of carbamazepine-induced inappropriate AVP secretion and water intoxication must be very uncommon and probably represent idiosyncratic responses.

Drug interactions I: detection of inorganic nitrite in organic nitrate esters under acidic conditions simulating the human stomach

Both unformulated (bulk) and formulated (drugs) organic nitrate esters (isosorbide dinitrate, nitroglycerin, and pentaerythritol tetranitrate) were studied in the presence and absence of hydrochloric acid to determine if they could be sources of nitrite (and therefore lead to nitrosamine formation) under acidic conditions similar to those found in the stomach. The presence and generation of nitrite ion was detected by a modification of the Griess reaction. Bulk isosorbide dinitrate and nitroglycerin were found to be contaminated with 13.8-121.4 mumoles of inorganic nitrite per mole of nitrate ester. In addition, in the presence of hydrochloric acid, these preparations generated 0.52-1.18 mumoles of inorganic nitrite/mole of nitrate ester/min. Unformulated nitroglycerin generated nitrite at a rate roughly twice that of isosorbide dinitrate. In contrast, no evidence for nitrite contamination or generation by pentaerythritol tetranitrate was found. Tablets and capsules of isosorbide dinitrate contained approximately 27-216 mumoles of nitrite/mole of nitrate ester and, in the presence of hydrochloric acid, generated an average of 0.55 mumole nitrite/min. For isosorbide dinitrate, this rate was similar for bulk and formulated drug. In comparison to isosorbide dinitrate, the amount of nitrite initially present in tablets and capsules of nitroglycerin varied more widely (approximately 25-2290 mumoles nitrite/mole of nitrate ester), and in this case nitrite was generated at higher rates than unformulated drug averaging approximately 4.7 mumoles nitrite/mole of nitrate ester/min. Contrary to a literature report, we found that nitrate ion is not reduced to nitrite by hydrochloric acid (pH 1-3).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemifacial spasm: treatment by microsurgical facial nerve decompression

The literature on hemifacial spasm and its surgical therapy is reviewed, and the authors' experiences with 20 patients are described. Vascular cross compression of the facial nerve adjacent to the brain stem is seen in 90% of the surgical patients. Mobilizing the offending vessel will cure or significantly improve approximately 80% of the patients. Complications occur in 25% of the patients and usually involve decreased hearing or facial weakness. Mortality is virtually zero, and this operation is vastly superior to any other medical or surgical therapy for hemifacial spasm. The pathophysiology is not yet understood.

Drug interactions. II. Formation of nitrosamines from therapeutic drugs. Properties and kinetics of the formation of N-nitrosopropranolol from nitrite and the secondary amine propranolol hydrochloride

In the presence of hydrochloric acid, nitrosamines may be generated from amines and nitrite. Most nitrosamines are carcinogens and many commonly used drugs contain potentially nitrosatable amine groups. Beta-adrenergic blockers, which have such amine groups, are widely prescribed and are often ingested for the lifetime of the patients, but their safety with respect to the intragastric formation of nitrosamines has not been established. The studies in this and the following report were designed to assess the potential risk posed by the endogenous formation of a nitrosamine in the stomach to individuals receiving longterm treatment with propranolol hydrochloride. The putative nitrosamine, N-nitrosopropranolol (NNP), was synthesized and its stability was examined under various experimental conditions. A high-pressure liquid chromatographic method was developed which detects a minimum of 7 X 10(-11) mol of NNP in the presence of large quantities of unreacted drug. Preparations of propranolol hydrochloride were found to contain several non-nitrosamine contaminants, which were removed before kinetic studies. At 37 degrees C, in solutions of HCl within the pH range found in the stomach, the optimum pH for the formation of NNP was 3. The yield of NNP increased linearly as incubation time and concentration of propranolol increased and exponentially as the concentration of nitrite was raised. Under optimal conditions in hydrochloric acid, the minimum concentration of nitrite required for the production of detectable amounts of NNP was 10(-5) M.

Drug interactions. III. Formation of nitrosamines from therapeutic drugs. Formation, mutagenic properties and safety assessment of propranolol hydrochloride with respect to the intragastric formation of N-nitrosopropranolol under conditions found in patients

In the preceding report, the kinetics of formation of N-nitrosopropranolol (NNP) from propranolol and inorganic nitrite were determined in solutions of hydrochloric acid over the range of pH similar to that found in the human stomach. In this communication, NNP formation was examined in human gastric juice and in the presence of organic nitrate ester vasodilator drugs. In comparison to HCl solutions, equivalent concentrations of propranolol and nitrite produced similar amounts of NNP in gastric juice; however, the yield increased as the pH was lowered and the kinetics of nitrosamine formation were different. Endogenous nitrite concentrations in 22 samples of human gastric juice were below the minimum concentration (10(-5) M) required for production of detectable levels of NNP. Maximal therapeutic dosages of propranolol (10(-2) M) incubated with isosorbide dinitrate (3,4-6.8 X 10(-3) M) or nitroglycerin (8.6 X 10(-4) M) also failed to produce NNP. However, NNP formed adventitiously during the concentration of aqueous and methylene chloride solutions that contained propranolol and organic nitrates, underscoring the importance of avoiding artifactual formation of nitrosamines. Furthermore, synthetic NNP was not mutagenic in either the Ames tester strains (TA92, TA98, TA100, TA1535, TA1537 and TA1538) or the hepatocyte-mediated mammalian cell mutagenesis assay. We conclude that NNP is unlikely to form in the stomach under conditions normally present in patients. Moreover, even if NNP formed under exceptional circumstances, this compound is unlikely to be a carcinogen. With respect to the potential formation of nitrosamines during drug dissolution in the stomach, long-term therapy with propranolol hydrochloride appears to be safe.

Sexual experience and plasma testosterone levels in male veterans after spinal cord injury

Fifty men with spinal cord injuries (SCI) were asked to complete a questionnaire concerning their sexuality before and after injury. Medical examination confirmed the location and completeness of the injury and extracted information about genitourologic status. The respondents rated sexuality highly as a concern in living, and a wide variety of sexual techniques were reported. A marked decrease in sexual activity, satisfaction, and feelings of sexual adequacy was reported after injury, as compared to retrospective "before injury" responses, lack of opportunity being reported as causative by 66% of the subjects and insufficient personal satisfaction by 59%. Seventy-five percent of the subjects experienced sexual arousal from genital stimulation, and several methods of eliciting erection were cited. Orgasm was described by a variety of terms. Significant differences were found between quadriplegic and paraplegic patients in answers to several items, though there was generally no difference between cervical and thoracic groups, which were more specifically broken down with respect to motor or sensory/complete or incomplete lesions. Plasma testosterone levels were found to fall well within the normal adult male range, as were levels of free testosterone and serum sex binding protein. The resulting information demonstrated more sexual concern among men with SCI than the literature previously indicated.