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Biomedical subjects

W E Collins

Publications and source records attributed to W E Collins.

At least 307 records · Page 17Linked to original sources
PubMed1975

Altered secretion of gonadotropins and steroids resulting from delayed ovulation in the rat.

Rats were killed by decapitation at 3-h intervals during a 48-h delay of ovulation induced by sodium pentobarbital, as well as during the ensuing delayed proestrus, estrus and the first 4 days of gestation. Control animals were killed at the same intervals following injections of vehicle. Blood was collected and analyzed for LH, FSH, prolactin, progesterone and estradiol-17beta to determine if alterations in hormonal levels could account for the abnormal embryonic development which follows delayed ovulation. Hormonal concentrations in plasma were measured by radioimmunoassay except for progesterone, which was determined by competitive protein binding. Embryos were examined to verify the occurrence of abnormal development. Rate of oocyte maturation was studied in serial sections of ovaries from all animals killed at 30-min intervals on the afternoon of proestrus. Oocytes remained in meiotic arrest during the 48-h delay of ovulation, but resumed maturation at the expected time on the afternoon of the preovulatory surge of gonadotropins. Following delayed ovulation there was a significant increase in fertilized ova that were undergoing degeneration (6.5 vs 1.9%), abnormal development (3.7 vs 0.7%), and retarded development (3.1 vs 0.2%). A number of alterations in hormonal levels occurred during the prolonged preovulatory period. The proestrous surge of LH in plasma was completely suppressed on both days of treatment with Nembutal, but exhibited a normal preovulatory peak on the following day. FSH showed a small but significant rise on both days of treatment. Peak concentrations of FSH on the following day were not different in magnitude from the normal preovulatory surge, although the duration of this surge was shortened by 12 h. Prolactin and progesterone concentrations in plasma were only partially suppressed on the days of treatment, while on the following day preovulatory levels of prolactin were significantly greater than in controls. The proestrous peak levels of estradiol occurred prior to the first Nembutal injection and declined more gradually after this treatment. Plasma levels of estradiol remained above basal levels during the period of delayed ovulation with peaks of short duration at 15u0 h on the day of second treatment and the day prior to ovulation. Plasma levels of these 5 hormones during the first 4 days of gestation were not altered by delayed ovulation.

Animals↗
PubMed1975

Application of the indirect fluorescent antibody method in a study of malaria endemicity in Mato Grosso, Brazil.

Four surveys of malaria endemicity were conducted in the Cuiabá Sector of Mato Grosso State, Brazil, at 6-month intervals during the period April 1970 to September 1971; during April 1970 a survey was also conducted in the Campo Grande Sector. Over 4,000 dual specimens--blood films for parasite diagnosis and filter paper blood spots for determination of fluorescent antibody (IFA) response--were collected from the general population, including school populations whenever possible. Parasitologic examinations yielded positivity rates ranging from 0.8 to 2.3%. In the Cuiabá Sector, sero-positives (larger than or equal to 1:20) ranged from 9.3 to 13.6%; in the survey in the Campo Grande Sector only 4.3% of the specimens were positive. There was an expected increase in IFA response with age in both the proportion of positives and mean maximum titers. In the Cuiabá surveys 75 to 91% of the maximum positive responses were to the Plasmodium falciparum antigen, while in Campo Grande only 46% of the maximum titers were for P. falciparum. The wide differences in malaria endemicity observed within the Cuiabá Secctor were attributed to differences in climate, geography, and degree of development of the several regions. A study of surveillance reports from 1966 through the survey dates revealed that the high rates of infection seen often resulted from detection activities in the larger cities and probably represented cases imported from endemic areas to the north and west. In order to interpret accurately the endemicity of malaria in an area and, thus, determine the necessity for introduction or continuation of control measures, thorough epidemiologic studies are necessary. The addition of a serologic method to normal surveillance can increase the accuracy of interpretation.

Adolescent↗
PubMed1975

Development of antibodies to Plasmodium vivax as measured by two different serologic techniques.

Sera from individuals infected with Plasmodium vivax were tested for the presence of malarial antibodies using the indirect fluorescent antibody (IFA) and the indirect hemagglutination (IGA) tests. The primary infection resulted in the conversion of all sera to a positive response in the IFA test, whereas only 50% gave a positive IGA response. There was a direct relationship between the duration of the primary parasitemia and percentage giving positive IGA response. Relapse resulted in high level positive IFA and IGA responses.

Antibodies↗
PubMed1975

The seroepidemiology of malaria in Middle America. I. Longitudinal studies on populations in a low incidence area of El Salvador.

Serologic profiles were established using the indirect fluorescent antibody test in a longitudinal study of six villages in an interior area of El Salvador. Positive serologic responses as well as active cases found through the voluntary collaborator posts occurred primarily in adult males, suggesting that much of the malaria experience in the study area resulted from exposure of this segment of the population in more malarious areas where they traveled to engage in temporary agricultural labor. Malaria incidence was generally low but transmission potential apparently varied markedly even over relatively small distances. Serologic profiles reflected the malaria experience in the population sampled, but many localities were widely dispersed and samples taken from village centers were found in some cases not to be representative of the entire locality population in terms of malaria exposure. The indirect fluorescent antibody technique was found to reflect the malaria experience in the population segments examined. When these data were correlated with the surveillance data from the voluntary collaborator posts, the epidemiology of malaria in the study area was more thoroughly understood.

Adolescent↗
PubMed1975

The seroepidemiology of malaria in Middle America. II. Studies on the Pacific coast of Costa Rica.

Serologic studies for malaria using the indirect fluorescent antibody technique suggest that active transmission is either absent or very low in 6 villages on the Pacific side of Costa Rica. Positive titers (1:20 or higher) were seen in the under-15-year age group in three of the study localities, but only 5 such responses were encountered among 249 people examined in this age range. In the adults (15 years and over) from the same 3 villages there were 68 positive titers among 161 examined. There were 43 positive responses in 189 adults from the remaining 3 villages where none of 307 persons under 15 years of age showed a titer of 1:20 or higher to any of the 3 malaria antigens tested (Plasmodium falciparum, P. vivax and P. malariae). These data suggest that the positive responses in the latter villages are more likely to be associated with old or imported cases than with current local transmission. Serologic responses of 1:80 or higher to the P. falciparum antigen suggested the continued presence of this parasite in the population in spite of the paucity of positive blood smears with this species in recent years. Positive titers with the P. malariae antigen suggest that this parasite is probably still present in the area. Such serologic studies help to indicate areas where malaria transmission is active and provide information on parasite reservoirs in particular populations.

Adolescent↗
PubMed1975

Predictive validities of several clinical color vision tests for aviation signal light gun performance.

Scores on the American Optical Company (AOC) test (1965 edition), Dvorine test, Farnsworth Lantern test, Color Threshold Tester, Farnsworth-Munsell 100-Hue test, Farnsworth Panel D-15 test, and Schmidt-Haensch Anomaloscope were obtained from 137 men with color-defective vision and 128 men with normal color vision. The validity of each of these tests in predicting scores on the aviation signal light gun was assessed by using daytime and nighttime administrations of the light gun as the criteria. Two "best sets" of plates from the AOC and Dvorine tests were selected by calculating a multiple regression equation in a stepwise manner with the nighttime and then the daytime administration of the signal light gun test as the criteria. Based on a graphic presentation of the miss and false alarm rates for each test at various possible cut scores, suggestions were made regarding the use of each test and the selection of optimal pass/fail scores.

Aerospace Medicine↗
PubMed1975

Some effects of alcohol on various aspects of oculomotor control.

Recent studies have shown that alcohol interferes with visual control of vestibular nystagmus. The present study was designed to assess three partially independent systems of oculomotor control. Performance on three tasks was measured before and after mild alcohol dosage. One task involved visual suppression of vestibular nystagmus; a second involved smooth oculomotor tracking of a moving target; and a third required repetitive rapid voluntary shifts in gaze. Oculomotor control was degraded on the first two tasks with recovery toward the initial performance level 4 h after drinking. Performance on the third task was not obviously degraded, although it is possible that improvement with practice was retarded. Results are discussed in terms of neurological systems involved and kinds of flight tasks potentially affected.

Aerospace Medicine↗
PubMed1975

Effects of D-amphetamine and of secobarbital on optokinetic and rotation-induced nystagmus.

Although vestibular nystagmus is known to be affected by variations in mental states, little information is available about the effects of drugs on vestibular responses when a) subjects are either alert or relaxed, and b) visual stimuli are available or denied. In this study, 30 men were assigned to d-amphetamine sulphage (10 mg), secobarbital sodium (100 mg), or placebo (no drug) groups. With subjects alert in darkness, the drugs had no differential effect on rotation-induced vestibular nystagmus; when subjects were relaxed there was significantly less nystagmus than in the alert condition, particularly for the seco-barbital group. With vision permitted, d-amphetamine had no statistically different effect on nystagmus from the placebo. However, subjects given secobarbital were unable to use visual fixation effectively to suppress vestibular eye movements and their visual-following ability as measured by optokinetic nystagmus was also suppressed. Control over the mental activity of subjects and assessment of oculomotor-related functions both with and without opportunities for visual fixation are both important in evaluating drug effects.

Adult↗
PubMed1975

Studies on the transmission of simian malaria. VI. Mosquito infection and sporozoite transmission of Plasmodium fragile.

Anopheles b. balabacensis mosquitoes were infected with Plasmodium fragile when fed upon splenectomized Macaca mulatta monkeys. Highest level mosquito infections were obtained when feedings were made from 2 to 4 days prior to the peak in the parasitemia. Transmission to M. mulatta monkeys was obtained via mosquito bite on 2 occasions and via intrahepatic and intravenous inoculation of dissected infected salivary glands on 9 occasions. The prepatent periods ranged from 12 to 17 days with a median of 15 days.

Animals↗
PubMed1975

TNM classification of malignant tumours of the bladder, prostate, testis and kidney.

TNM classification is a short description of a cancer at a point in its natural history--the onset of definitive treatment--and should be considered in planning treatment, in assessing prognosis, in evaluating end results, in facilitating the exchange of information between treatment centres and thus in contributing to the continuing investigation of human cancer. For four cancers of urologic sites there are new TNM classifications. Although previous classifications of bladder cancer were satisfactory, the new classifications for kidney, prostate and testis are the first internationally accepted classifications for these three organs that are clinically practical. Widespread use of these classifications is recommended.

Female↗
PubMed1975

Effects of mechanical vibration on rat plasma calcium, magnesium, phosphate, and xanthine oxidase.

Sprague-Dawley rats were vibrated for 4 min in one of 12 combinations of G levels (+/-2, +/-4, or +/-8 GX) and frequency ranges (12-61, 62-111, 112-161, or 162-211 HZ). The animals were restrained and conscious during vibration. Plasma calcium, magnesium and inorganic phosphate concentrations as well as xanthine oxidase activities were determined for each animal at various times before and after vibration. Vibration at specific G levels induced physiological changes in plasma calcium, magnesium, and xanthine oxidase levels. Plasma inorganic phosphate concentrations appeared to increase with an increase in the displacement of vibration. All of the effects observed occurred within 24 h of vibration treatment. An effect of the frequency of vibration was not observed with any of the parameters examined. Factors involved in performing the experiments also were able to induce certain physiological changes, viz., the level of plasma calcium and xanthine oxidase activity.

Animals↗
PubMed1974

Relationship of serum complement levels to events of the malarial paroxysm.

Malarial paroxysms due to Plasmodium vivax were studied for alterations in whole serum complement (C') and certain C' components. The objective was to relate C' values with events of the parasite cycle during schizogony and with the febrile pattern. Substantial decreases in C' were found in 9 of 18 paroxysms studied during relapse. In contrast, only one of 22 paroxysms occuring during the primary attack was associated with a striking depression in C', and this case exhibited certain characteristics of a relapse paroxysm. The mean change in C' levels during paroxysms in relapse (-23%) was significantly different from paroxysms of the primary attack (-2%). Depletion of C' was associated directly with degree of parasitemia and presence of complement-fixing (CF) antibody. Lowest levels of C' were found within a few hours after completion of schizont repture and peak fever. C4 levels reflected changes in whole serum C' and appeared to be a more sensitive indicator of C' alterations during malaria. While the alterations in C4 as well as C1 and C2 indicated that the classical C' pathway was involved, some preliminary results showed little or no depletion of late components, C3 and C6. Overall results are compatible with C' activation and depletion during or soon after schizont repture if parasite density is sufficiently high and if CF antibody is present.

Adult↗