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S M Martin

Publications and source records attributed to S M Martin.

At least 55 records · Page 3Linked to original sources
PubMed1988

Recommendations for the use of Taylor series confidence intervals for estimates of vaccine efficacy.

A simple formula for calculating confidence intervals by means of a Taylor series variance approximation has been recommended for gauging the precision of estimates of vaccine efficacy. To evaluate the performance of Taylor series 95% confidence intervals for vaccine efficacy, we conducted a simulation study for commonly expected values of vaccine efficacy, risk of disease in the unvaccinated population, and sample sizes of the vaccinated and unvaccinated groups. In the first simulation, the sample size in the vaccinated group was 500 or 1000, whereas that in the unvaccinated group ranged from 10 to 1000. The confidence intervals were accurate when the sample size in the unvaccinated group was >/=50 and the risk of disease was 0.3-0.9. In contrast, the intervals were too narrow when all three of the following situations occurred: the number of unvaccinated was small (10 or 20), the true vaccine efficacy was relatively low (60% or 80%), and the risk of disease was 0.5-0.9. Furthermore, when the true vaccine efficacy was high (90% or 95%) and the disease risk in the unvaccinated was low (0.1 and 0.2), the confidence intervals were too broad, especially when the unvaccinated sample size was <50. Additional simulations with a sample size in the vaccinated group of 200 gave broad intervals for 95% vaccine efficacy (for all values of disease risk) and for 90% vaccine efficacy when the disease risk was </=0.3.

Epidemiologic Methods↗
PubMed1987

Yersinia enterocolitica infections and pork: the missing link.

To determine the risk factors for Yersinia enterocolitica (YE) infection in Belgium, which is the country with the highest incidence of this infection, 40 persons with YE infections due to serotype O:3 (n = 36) or O:9 (n = 4) were compared with matched controls. Most patients had acute gastroenteritis; 1 had a liver abscess. 20% were admitted to hospital; the mean duration of hospital stay was 9 days. YE infection was strongly associated with eating raw pork in the 2 weeks before onset (odds ratio = 12, p = 0.00002), a factor that accounted for 58% of the YE infections studied. 14 (18%) of 79 families surveyed at a well-baby clinic fed their children raw pork from a median age of 18 months. Specific control measures to reduce contamination and consumption of raw pork may reduce the incidence of YE infections.

Animals↗
PubMed1987

Mathematical separation of multi-component exponential signals from the u.v. laser excitation of glycogen phosphorylase b.

Laser excitation of the vitamin B6 cofactor of the glycogen phosphorylase enzyme produces a transient absorbance signal at 470 nm. Martin et al. proposed four exponential decays for this complex signal. One component with the largest amplitude and a decay rate constant in the region of 150,000 s-1 results from an excited singlet state, and three successive decays of smaller amplitude with the rate constants in the regions of 700,000 s-1, 30,000 s-1, and 6000 s-1 result from a triplet state. These results were determined through nonlinear least squares regression and residual analyses, with some knowledge of the possible photochemistry of the cofactor by itself. The Fourier transform method, which requires no initial estimates of the parameters or of the number of decays, was selected for further analysis of the data. The results of the Gardner and differential approaches to the method confirm that the predicted four exponential components are in the signal and that the values of the decay rate constants agree with those from the nonlinear regression analysis. These results, presented here, help to demonstrate protein changes at the active site of enzyme catalysis.

Animals↗
PubMed1986

Protein dynamics of glycogen phosphorylase.

The glycogen phosphorylase molecule absorbs the ultraviolet energy of a nitrogen laser to form an excited state of the cofactor. The decay rate of this state has a lifetime of 6.7 microseconds, and its sensitivity to bound substrates presents a new perspective of the mechanism. A careful analysis of the decay curve for native enzyme and cofactor analogues showed that the lifetime depends on the conformation of protein groups at the active site and how the residues change with bound substrate. The reactive ternary complexes obtained from either direction of the reaction yielded the same lifetime, indicating a change in the active-site conformation to a common configuration for the cofactor and substrate phosphate. This configuration indicates an increase in the cofactor 5'-PO4 pKa and a possible proton shuttle. The pyridoxal 5'-pyrophosphate reconstituted enzyme showed no conformational change alone or in the presence of oligosaccharide. This result does not support an electrophilic attack by the 5'-PO4 phosphorus.

Animals↗
PubMed1985

The action of centrally administered arginine vasopressin on blood pressure in the conscious rabbit.

In addition to its peripheral endocrine actions, arginine vasopressin (AVP) has been implicated in the central control of blood pressure. Intracerebroventricular (i.c.v.) injections (0.01-1.0 nmol) of AVP or arginine vasotocin (AVT), but not oxytocin (OXY), into unanesthetized rabbits caused a rapid, dose related rise in blood pressure as well as increases in heart rate. The lowest centrally administered dose of AVP and AVT (0.01 nmol) had no effect on blood pressure when given intravenously. In search of tissue locus for the pressor effect of AVP microinjection of AVP and OXY into the posterior hypothalamus and septum of conscious rabbits was without effect. However, microinjection (0.01-0.04 nmol) of AVP into the nucleus tractus solitarius of anesthetized rabbits caused a rise in blood pressure similar to the response seen after i.c.v. injection. Comparable volumes of the vehicle into the ventricle or the tissue sites had no effect on resting blood pressure. The pressor response after AVP given i.c.v. was significantly reduced up to 3 h after administration of the ganglionic blocker, chlorisondamine HCl. The central antagonist, d(CH2)5Tyr (Me) vasopressin, eliminated the usual increase in blood pressure after administration of AVP in half the animals tested. The results indicate that AVP acts centrally to mediate cardiovascular responses in unanesthetized as well as anesthetized rabbits.

Animals↗
PubMed1985

Temperature effects on evoked potentials of hippocampal slices from euthermic chipmunks, hamsters and rats.

1. Neural activity was recorded in hippocampal slices from euthermic chipmunks, hamsters and rats. 2. While recording the evoked potentials, the temperature of the Ringer's solution bathing the slice was varied by controlling the temperature of an outer chamber jacketing the recording chamber. 3. The temperature just below that at which a population spike could be evoked, Tt, was 10.4 +/- 0.3 degrees C (mean +/- SEM) for chipmunk slices, 14.1 +/- 0.4 degrees C for rat slices and 14.8 +/- 0.4 degrees C for hamster slices. Tt was significantly lower in the chipmunk slices (P<0.01) than in the rat and hamster slices. 4. Data were interpreted as consistent with the hypothesis that chipmunk hippocampal neurons are intrinsically cold resistant.

Animals↗
PubMed1984

A technique for determining prosthetic joint contact areas.

A technique to determine the contact areas of total joint replacements has been developed. A thin film of petroleum jelly is deposited by the metallic component on the plastic component when load is applied. Fingerprint powder is then used to highlight the petroleum jelly coated area. Experimental data produced using this technique was found to be in good agreement with theoretical predictions.

Joint Prosthesis↗
PubMed1984

Importance of host factors in human salmonellosis caused by multiresistant strains of Salmonella.

Antimicrobial resistance patterns of Salmonella isolates from persons in randomly selected urban and rural counties in the United States were examined along with clinical and epidemiological characteristics of the host. Multiresistant strains, isolated from 66 (12.2%) of 542 persons evaluated, were associated with five of 20 variables in univariate analyses: serotype heidelberg, host of Hispanic origin, host exposure to penicillins within four weeks before stool culture, age greater than or equal to 60 years, and regular antacid use. By multiple linear regression, the first three variables were each significantly associated with infections due to multiresistant Salmonella. One or more of the last three variables, thought to be host factors that may promote disease, were present for persons yielding 38% of multiresistant strains but only 12% of sensitive strains (P less than .001). The relatively large proportion of multiresistant Salmonella among isolates from persons with these risk factors suggests that to cause disease, resistant organisms are more dependent than are sensitive organisms on host characteristics.

Adolescent↗
PubMed1984

Propagation of Rhizopus javanicus Biosorbent.

After propagation of Rhizopus javanicus in defined media containing glucose, urea, and mineral salts in deionized distilled water, the ability of the nonliving biomass to sequester cupric ion was assayed. Growth, uptake capacity (saturation uptake at >1 mM Cu concentration in solution), and biosorptive yield (biomass concentration x uptake capacity) were increased by augmentation of the growth medium with mineral salts once growth was under way. In the stationary phase, the uptake capacity of mycelia, which were normally a poor biosorbent, was improved within 4 h of trace metal addition to the growth medium. Growth of the culture was inhibited by excessive concentrations (0.04 to 40 muM) of metals in the medium in the following order: Cu > Co >/= Ni > Mn > Mo; zinc was not inhibitory at 40 muM, and chromium was stimulatory at 0.53 muM but slightly inhibitory at higher levels. Iron and potassium phosphate stimulated growth at levels of 0.53 and 40 mM, respectively. When R. javanicus was propagated in a medium with a high salt concentration, exponential growth (0.23 h) to a biomass concentration of >3 g/liter and a biosorptive yield of >500 mumol/liter was achieved. It is evident that the powerful biosorbent characteristics of Rhizopus biomass led to depletion of available trace minerals in suspension culture, which in turn limited growth.

Journal Article↗
PubMed1982

Effects of cortisol administration on development of the thyroid and adrenal axes in rats.

Intraperitoneal (IP) injections of cortisol were administered to neonatal male rats on postnatal days 1 to 4. Plasma triiodothyronine (T3), thyroxine (T4) and corticosteroids were determined on days 5, 10, 13, 16, 20, 30 and 60 of age, and all animals were weighed weekly. Neonatal cortisol treatment resulted in depressed body weight gain and transient depression in plasma T4. These results indicate that while body weight is significantly affected by cortisol treatment ontogenic patterns of plasma T3, T4 and corticosteroids develop normally.

Adrenal Cortex↗
PubMed1982

Intravenous nitroglycerin in acute coronary artery disease.

Intravenous nitroglycerin (IVNG) was used in 12 instances (11 patients) to relieve pain, following myocardial infarction or unstable angina. The strength of IVNG infusion could be easily controlled and relief of pain was prompt and satisfactory. Excessive tachycardia or severe headache was not encountered and marked hypotension was seen in one patient only. This patient had three vessel coronary artery disease, extensive myocardial damage and vein graft closure. Cardiovascular stability was provided by IVNG, prior to and during cardiac catheterisation and cineangiography, transportation to another hospital and vein graft surgery. IVNG appears to be a safe and effective drug in the management of patients with acute coronary artery disease (unstable angina and myocardial infarction). In those with both right and left ventricular wall infarction, however, the usefulness of IVNG needs to be established.

Acute Disease↗
PubMed1981

Secular trends in nosocomial infections: 1970-1979.

Nosocomial infection data from a mean of 81 hospitals has been reported to the National Nosocomial Infections Study (NNIS) each year since 1970. Surveillance has been conducted by the hospitals on an average of 1.16 million patients annually. The median nosocomial infection rate is 341 per 10,000 patients discharged, ranging from 312 in 1970 to 358 in 1975. Since 1975, the rate has steadily declined to 329 in 1979. By category of hospital, infection rates for community-teaching and municipal hospitals have declined in recent years whereas those for community and university hospitals have not. Infection rates for patients on the surgical service have declined steadily since 1975 to the lowest levels reported, 457 per 10,000 surgical patients discharged in 1979, primarily due to a decrease in the rate of surgical wound infections. On obstetrics, infection rates have increased steadily since 1970, also primarily due to surgical wound infections. Bacteremias have increased in frequency, particularly those associated with infection at other sites. No major shifts have been noted in the relative frequency of the most common sites of infection or pathogens causing infections.

Cross Infection↗
PubMed1981

Conversion of Cellulose to Methane and Carbon Dioxide by Triculture of Acetivibrio cellulolyticus, Desulfovibrio sp., and Methanosarcina barkeri.

The fermentation of cellulose by monocultures of Acetivibrio cellulolyticus and cocultures of A. cellulolyticus-Methanosarcina barkeri, A. cellulolyticus-Desulfovibrio sp., and A. cellulolyticus-M. barkeri-Desulfovibrio sp. was studied. The monoculture produced ethanol, acetate, H(2), and CO(2). More acetate and less ethanol was formed by the cocultures than by the monoculture. Acetate was utilized by M. barkeri in coculture with A. cellulolyticus after a lag period, whereas ethanol was metabolized by the sulfate reducer only under conditions of low H(2) partial pressure, i.e., when cocultured with A. celluloyticus-M. barkeri or when grown together with the methanogen. Only the three-component culture carried out the rapid conversion of cellulose to CO(2) and methane. Furthermore, this culture hydrolyzed the most cellulose-85% of that initially present. This amount was increased to 90% by increasing the population of M. barkeri in the triculture. Methane production was also increased, and a quicker fermentation rate was achieved.

Journal Article↗