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Biomedical subjects

R Gay

Publications and source records attributed to R Gay.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of butyric and acetic acids on acetone-butanol formation by Clostridium acetobutylicum.

The actions of butyric and acetic acids on acetone-butanol fermentation are investigated. Production of butyric and acetic acids are controlled by the extracellular concentrations of both acids: acetic acid added to the medium inhibits its own formation but has no effect on butyric acid formation, and added butyric acid inhibits its own formation but not that of acetic acid. The ratio of end metabolites depends upon acetic and butyric acid quantities excreted during the fermentation. In contrast to acetic acid, which specifically increases acetone formation, butyric acid increases both acetone and butanol formations. Acetate and butyrate kinase activities were also examined. Both increase at the start of fermentation and decrease when solvents appear in the medium. Coenzyme A transferase activity is weak in the acidogenic phase and markedly increases in the solvent phase. Acetic and butyric acids appear to be co-substrates. On the basis of these results, a mechanism of acetic and butyric acid pathways, coupled to solvent formation by C. acetobutylicum glucose fermentation is proposed.

Acetate Kinase↗
PubMed1987

Radio-carpal and inter-carpal degenerative arthritis in sequellae of scaphoid injuries.

Degenerative arthritis is a frequent pattern after old fractures or rotatory subluxations of the scaphoid. The authors have studied this phenomenon, on 48 wrists. In old scaphoid fractures, the degenerative arthritis begins with an impingement between radial styloid process and proximal pole of the scaphoid, and then reaches the lunocapitate joint. A dorsi flexion by instability is then constant. After a scaphoid subluxation, degenerative arthritis begins between scaphoid and radial epiphysis too, but arthritis in these cases, is earlier and more symptomatic. We found two types of wrists: the sequellae of the post-traumatic scapholunate diastasis and the peri-scaphoid arthritis "primary in appearance", which corresponds to the scapholunate advanced collapsed pattern of A.K. Watson.

Adult↗
PubMed1987

Multicenter comparison of MicroScan and BACTEC blood culture systems.

Recently, MicroScan (Baxter MicroScan Div., W. Sacramento, Calif.) introduced a radiolabeled-blood-culture system that is compatible with the BACTEC 460 (Johnston Laboratories, Inc., Towson, Md.). A multicenter blood culture study was initiated to evaluate this new system. Approximately 20 ml of blood was obtained from each patient and divided equally between BACTEC and MicroScan bottles which were incubated and processed identically. Aerobic bottles were examined twice on days 1 and 2 and once on days 3, 4, 5, 6, and 7. Anaerobic bottles were examined once a day for 7 days. There were 3,451 cultures evaluated, and 414 of these subsequently grew microorganisms. Of these positive cultures, 64 were judged to be contaminated. Of the remaining 350 positive cultures, 253 grew in both systems, 54 grew in BACTEC bottles only, and 43 grew in MicroScan bottles only. The average times to detect positive cultures were 1.8 and 2.1 days by the BACTEC and the MicroScan systems, respectively. No significant difference in the number or kind of organisms recovered or in the detection times for positive cultures was observed between the two blood-culturing systems.

Aerobiosis↗
PubMed1987

Control of cardiac function and venous return in thyrotoxic calves.

The mechanisms responsible for maintenance of the high-output state associated with thyrotoxicosis have been investigated by measurement of cardiac-function curves and venous compliance during ganglionic blockade with trimethaphan. Thirteen calves were injected daily with L-thyroxine (200 micrograms/kg) for 12-14 days. Thyroxine treatment increased heart rate (70%), left ventricular systolic pressure (22%), cardiac output (120%), left ventricular maximum rate of pressure development (dP/dt) (56%), and total blood volume (18%) and decreased systemic vascular resistance (39%). These hemodynamic changes persisted during ganglionic blockade or autonomic blockade with atropine and propranolol. Cardiac-function curves in conscious thyrotoxic calves were displaced upward and to the left. Mean circulatory filling pressure (MCFP), measured during anesthesia, was increased from 8 +/- 1 to 12 +/- 1 mmHg. During autonomic and ganglionic blockade MCFP remained elevated after treatment with thyroxine. Venous compliance decreased from 2.1 +/- 0.2 to 1.3 +/- 0.1 ml X mmHg-1 X kg-1 after thyroxine. Unstressed vascular volume was increased from 52.3 +/- 1.1 to 67.1 +/- 0.9 ml/kg. Thus the elevated cardiac output and new cardiac-function curve in thyrotoxicosis are associated with a combination of increased inotropic state, increased blood volume, and decreased venous compliance. These effects are not the result of autonomic influences and may represent direct actions of thyroid hormone on the heart and peripheral venous circulation.

Animals↗
PubMed1987

Effects of L-thyroxine in rats with chronic heart failure after myocardial infarction.

The effects of thyroid hormone on left ventricular (LV) function and myosin isoenzyme distribution were evaluated in rats 3 wk after myocardial infarction. When compared with normal rats, animals selected for study had moderately severe LV dysfunction as judged by decreased aortic and LV systolic pressures and a 34% decrease in LV maximum rate of pressure development (dP/dt). Average LV end-diastolic pressure was increased to 26 +/- 1 mmHg from 5 +/- 1 mmHg. The infarcted rats were divided into saline-treated control (n = 10) and treatment (n = 13) groups. The latter group received thyroxine (T4, 1.5 micrograms/100 g body wt) immediately after the first determination of pressures and at 24 and 48 h. At 72 h, aortic and LV pressures and myosin isoenzyme composition were measured. In the thyroxine-treated group LV end-diastolic pressure decreased from 27 +/- 2 to 18 +/- 2 mmHg, and LV dP/dt increased from 5,627 +/- 249 to 6,064 +/- 355 mmHg/s. Heart rate and aortic pressure did not change. After saline injections, LV end-diastolic pressure remained elevated, and the other hemodynamic parameters were unchanged. Determination of ventricular myosin isoenzyme composition in the saline-treated group revealed an increase in the V3 myosin isoform and a decrease in the V1 isoform as compared with the normal values. This pattern was not altered by T4 treatment. A separate group (n = 7) of rats was treated with a 10 times larger dose of thyroxine (15 micrograms/100 g body wt) for the same period of time. In this group, there was neither hemodynamic improvement nor changes in myosin isoenzyme distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[Role of acetate and butyrate in the induction of NADH: rubredoxin oxidoreductase in Clostridium acetobutylicum].

Study of the biosynthesis of NADH: rubredoxin oxidoreductase in resting cells of Clostridium acetobutylicum shows that this enzyme is synthesized at a maximal rate in the presence of acetic acid at a concentration of 3 g . l-1 and at pH 4.8. Protons do not play any role in this biosynthesis since no induction is observed in a medium without acetate for the same values of pH. Butyric acid at a concentration of 0.5 g . l-1 gives 50% induction and formic acid, isobutyric acid and propionic acid have no inductive action on NADH: rubredoxin oxidoreductase. These results are confirmed by studies using a dialysis bag. Only a culture against acetic acid at an initial concentration of 2 g . l-1 gives maximal biosynthesis of the enzyme, whereas a culture in which all products of metabolism are eliminated gives an activity which is 80% lower.

Acetates↗
PubMed1986

Total vascular pressure-volume relationship in conscious rats with chronic heart failure.

To define the changes in the venous circulation in chronic left ventricular (LV) failure, we measured the mean circulatory filling pressure (MCFP), blood volume, and effective vascular compliance in conscious rats with heart failure, 3 wk after coronary ligation. Rats with myocardial infarction and LV end-diastolic pressure (EDP) greater than 15 mmHg were considered to have chronic heart failure. Rats with chronic heart failure (n = 11) showed an increase (P less than 0.001) in LV EDP to 24 +/- 2 mmHg compared with 6 +/- 1 mmHg in sham-operated (n = 9) and 7 +/- 1 mmHg in normal (n = 6) rats. In the rats with chronic heart failure the MCFP was increased to 9.9 +/- 0.2 mmHg (P less than 0.001) compared with 7.6 +/- 0.2 mmHg in the sham-operated and 7.7 +/- 0.2 mmHg in the normal rats. Effective vascular compliance was determined from MCFP-blood volume curves. In rats with chronic heart failure, the effective vascular compliance was decreased to 2.40 +/- 0.08 ml X mmHg-1 X kg-1 from 3.34 +/- 0.16 in sham-operated rats and 3.35 +/- 0.22 ml X mmHg-1 X kg-1 in normal rats. The blood volume and the unstressed vascular volume of the rats with chronic heart failure were not statistically different from the sham-operated rats. These results suggest that venous capacitance is decreased in chronic heart failure, due to a decrease in effective vascular compliance with no significant change in unstressed vascular volume. Hexamethonium chloride did not alter the effective vascular compliance of the rats with heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Treatment of verapamil toxicity in intact dogs.

The treatment of verapamil toxicity was examined in lightly sedated dogs. Verapamil, administered as a bolus (0.72 mg/kg) followed by a continuous infusion (0.11 mg/kg per min), decreased cardiac output (CO) from 3.1 +/- 0.1 to 1.7 +/- 0.1 liter/min (P less than 0.001), heart rate (HR) from 85 +/- 4 to 57 +/- 3 beats/min (P less than 0.001), left ventricular derivative of pressure with respect to time (LV dP/dt) from 2,085 +/- 828 to 783 +/- 78 mm Hg/s (P less than 0.001), mean aortic pressure (AO) from 77 +/- 4 to 38 +/- 2 mm Hg (P less than 0.001) and stroke volume from 39 +/- 3 to 28 +/- 2 ml/beat (P less than 0.01). In verapamil-toxic animals isoproterenol increased HR, CO, LV dP/dt, and AO; calcium chloride increased LV dP/dt and AO; norepinephrine, epinephrine, and dopamine increased CO, AO, and LV dP/dt, atropine increased HR, CO, and AO. Phenylephrine (13-55 micrograms/kg per min) produced no changes except a small increase in AO while very high dose phenylephrine (300 micrograms/kg per min) increased AO, CO, and LV dP/dt. 4-Aminopyridine (4-AP) increased HR, CO, LV dP/dt, and AO. When administered prior to verapamil, 4-AP prevented the development of verapamil toxicity as shown by the significantly higher AO (P less than 0.001), CO (P less than 0.01), and LV dP/dt (P less than 0.01) when 4-AP followed by verapamil was compared to verapamil alone. In conclusion, there does not appear to be a single specific therapy for verapamil toxicity, however it can be partially corrected by presently available pharmacologic therapy and 4-AP.

4-Aminopyridine↗
PubMed1985

Differential levels of ferredoxin and rubredoxin in Clostridium acetobutylicum.

Ferredoxin and rubredoxin levels have been determined in DEAE-cellulose treated extracts of Clostridium acetobutylicum using specific enzymatic assays. In contrast to ferredoxin, the content of rubredoxin is affected by various culture conditions; it fluctuates in the proportions of 1 to 3 according to the growth phase, 1 to 8 according to the medium composition, and 1 to 40 according to the pH. Highest rubredoxin level is obtained at the end of the acid phase when the cells grow in chemically defined medium, the pH of which is not controlled. Such variations suggest that rubredoxin as well as rubredoxin-reductase take part in an electron transport chain system inducible by the culture conditions.

Carbohydrate Metabolism↗
PubMed1985

[Locoregional anesthesia of the foot for forefoot surgery].

A technique of regional anaesthesia of the foot for forefoot surgery (ingrowing toe-nail, hallux valgus, amputation, etc.) is described. It consists of a block of the superficial peroneal nerve at the ankle combined with a block of the posterior tibial nerve behind the medial malleolus. A volume of 5-6 ml of 1% lidocaine or 1% mepivacaine is injected. A pneumatic tourniquet was placed on the upper part of the thigh after the patient had been given an intramuscular premedication. The results of 52 such blocks carried out in 40 patients are discussed.

Adolescent↗
PubMed1985

Glomus tumors of the hand. Presentation of fourteen cases.

The authors report a series of fourteen patients with a glomus tumor in the hand. The major symptoms were excruciating spontaneous pain upon mechanical and thermal stimulation of the tumor. In subungual tumors, a blue discoloration is suggestive of diagnosis; but this was found in only 50 percent of cases. The difficult in correct diagnosis and therefore for complete removal is due to in the location of the tumor. Recurrence may occur in cases of incompletely removed tumor. In three cases, the tumor was submitted to electron microscopic examination which led to a better comprehension of the histogenesis of these tumors.

Adult↗
PubMed1985

Regulation and butanol inhibition of D-xylose and D-glucose uptake in Clostridium acetobutylicum.

Clostridium acetobutylicum exhibited diauxie growth in the presence of mixtures of glucose and xylose. Both glucose- and xylose-grown cells had a glucose uptake activity. On the other hand, growth on xylose was associated with the induction of a xylose permease activity, which was repressed by glucose in xylose-induced cells. The rate of sugar uptake with increasing sugar concentrations showed saturation kinetics with an apparent Km of 1.25 X 10(-5) M for glucose and 5 X 10(-3) M for xylose. Concomitant with the production of solvents, the activities of the glucose and xylose transport systems decreased. Among the main products of fermentation, butanol was shown to be a potent inhibitor of the growth of the organism and of the rate of sugar uptake as well as of sugar incorporation into cell materials. These inhibitory effects of butanol were more pronounced in xylose-grown cells than in glucose-grown cells. Butanol completely inhibited growth at a concentration of 14 g/liter for cultures growing on glucose and 8 g/liter for cultures growing on xylose. Concentrations of 7 and 10.5 g/liter of butanol caused a 50% inhibition of the xylose and glucose incorporations into cell materials. These inhibitory levels of butanol were found in typical glucose or xylose fermentation.

Biological Transport↗
PubMed1984

Morphological studies of the epiphyseal growth zone in the brachymorphic (bm/bm) mouse.

Light microscopy, including immunohistochemical techniques, and electron microscopy were performed on epiphyseal growth cartilage from brachymorphic (bm/bm) mice and age-matched phenotypically normal siblings aged 5, 16 and 25 days. In the bm/bm mice light microscopy showed a disturbed columnar arrangement and numerous chondrocytes with pronounced regressive changes. The normal development of proliferative cells into hypertrophic cells was halted and thus only a rather small and ill-defined hypertrophic zone was seen. The calcifying zone was irregular and the normal lacunae were replaced by a densely staining matrix. Using immunofluorescence techniques, the presence of considerable amounts of both type II and type V collagen was demonstrated in the bm/bm mice, while the cartilage from controls contained only type II. Ultrastructurally the lacunar matrix contained bundles of fine fibrils without the typical collagen periodicity which might indicate synthesis of a defective procollagen. Our observations together with the previously demonstrated deficiency of 3'-phosphoadenosine 5'-phosphosulphate, illustrate the complexity of the growth cartilage disturbance in the bm/bm mouse. Most of our findings are at variance with those described in the literature and possible pathogenetic mechanisms for the observed alterations in the growth cartilage are discussed.

Animals↗
PubMed1983

Collagen formation by the hepatocyte in primary monolayer culture and in vivo.

Immunohistochemical techniques were used to confirm biochemical evidence that parenchymal cells isolated from adult rat liver and maintained in nonreplicating monolayer culture for 2 days synthesized type IV basement membrane collagen. On continued incubation in serum-free medium, the hepatocytes also synthesized the interstitial collagens, types I and III. Consistent with these results in culture, type IV collagen was localized to the hepatocytes in slices of pathologic rat liver. Hence collagen formation is a previously unrecognized function of the hepatocyte that may be important in the pathogenesis of liver fibrosis or cirrhosis.

Animals↗
PubMed1983

[Effect of growth phase and composition of the medium on the rate of biosynthesis of NADH: rubredoxin oxidoreductase in Clostridium acetobutylicum].

Among the three strains of Clostridium acetobutylicum we investigated: NRRL 592, NCIB 619 and ATCC 824, only the last was shown to contain a NADH: rubredoxin oxidoreductase activity. We report that the biosynthesis rate of this enzyme fluctuated in the proportions of 1 to 50 according to the growth phase and medium composition. These variations reflect a mode of regulation adjusted to the metabolism of bacteria.

Clostridium↗