Search PubMed⌕ Search

Biomedical subjects

M Visser

Publications and source records attributed to M Visser.

126 records · Page 7Linked to original sources
PubMed1990

Pharmacodynamics of cefepime.

The microbiological activity of cefepime was assessed in vitro against 232 clinical isolates coupled with a pharmacokinetic evaluation at steady state in six patients receiving 1 g every 12 h. MIC90s were less than or equal to 0.25 mg/l for Enterobacteriaceae and streptococci. 1 mg/l for Staphylococcus aureus and 8 mg/l for Pseudomonas aeruginosa. Mean serum concentrations in patients were 62.5 +/- 2.7 mg/l (end infusion) and 1.1 +/- 0.8 mg/l (at 12 h) with an elimination half-life 2.72 +/- 0.59 h. These data together with those published for currently marketed cephalosporins were integrated to generate an Intensity Index incorporating both the magnitude and duration that drug concentrations exceed the MIC during steady-state dosing. Cefepime demonstrated comparable or superior indices to cefazolin against Gram-positive microorganisms and to cefuroxime and ceftazidime against Gram-negatives. Serum bacteriostatic and bactericidal activity from the kinetic samples corresponded with the duration that serum cefepime concentrations exceeded the MIC and MBC, respectively, for selected strains. This pharmacodynamic evaluation suggests that cefepime 1 g every 12 h potentially provides inhibitory serum concentrations for the majority of common Enterobacteriaceae, streptococci and S. aureus over the dosing interval but that higher doses or more frequent administration may be necessary for some pseudomonal infections.

Bacteria↗
PubMed1989

Bedside blood gas and electrolyte monitoring in critically ill patients.

A major advantage of near-patient testing is time savings that facilitate important diagnostic and therapeutic decisions. Recent technologic advances have made available a number of systems that allow for near-patient testing. The reliability of these instruments must be validated in the clinical setting in the hands of their intended users. We evaluated the Gemstat blood gas, electrolyte, and Hct portable analyzer in the critical care setting when used by numerous individuals with no previous laboratory training. Blood gas, Na, K, and Hct results were highly correlated with those from the clinical laboratories (PaO2, r = .96; PaCO2, r = .92, pH, r = .96; Na, r = .93; K, r = .95; Hct, r = .91). The Gemstat represents a new generation of portable, rapid, safe, and accurate instruments that are well suited for ICU settings. The instrument can facilitate clinical management of patients, and may improve patient care.

Blood Gas Analysis↗
PubMed1988

An evaluation of labeling-then-doing with moderately handicapped persons: acquisition and generalization with complex tasks.

We conducted two experiments in which moderately mentally retarded persons were trained first to label and then to enter characters into a computer, calculator, or checkbook (label-then-do) within a multiple baseline design. In Experiment 1, 5 young adults were trained to enter statistical programs into computers in an office setting. Following training, all subjects' use of verbal labels and key-entry skills generalized across tasks (programs) and settings (offices and computer terminals). In Experiment 2, 3 junior high school students were trained with self-labeling procedures to complete a key-entry task and to balance a checkbook. The performance of all students generalized across tasks and settings, and the use of labels generalized for 2 of the students. Results are discussed relative to mediated generalization and to establishing verbal control over behavior.

Adolescent↗
PubMed1985

Identical chromosome translocations involving the region of the c-myb oncogene in four metastases of a mediastinal teratocarcinoma.

A 39-year-old white male presented with a disseminated mediastinal teratocarcinoma. Karyotyping was performed on two mature residual metastatic lesions in the lungs immediately following chemotherapy, on a recurring lung lesion after 5 months, and on a metastasis in the right thigh 5 months after salvage chemotherapy. All four lesions were pseudoeuploid and showed identical chromosomal abnormalities: a translocation with the two chromosomes #6 and one chromosome #11 involved, resulting in 46, XY, t (6;6;11) (q21;q23;q13). The breakpoint in chromosome #6 is in the region to which the oncogene c-myb has been localized, and the breakpoint in chromosome #11 is at a known fragile and possibly oncogenic site, suggesting that the translocations in this case may have played a crucial role in the development of the malignancy.

Adult↗
PubMed1979

Life span changes in the presence of alpha-melanocyte-stimulating-hormone-containing cells in the human pituitary.

Since recent circumstantial evidence has suggested possible functions of alpha-MSH in intrauterine growth and labour, the presence of this hormone in the human pituitary was determined by means of the indirect immunofluorescence procedure during development and adulthood. Cross reaction of the antibodies with other peptides was measured after which they were purified by solid phase absorption. Experiments on the rat pituitary showed that staining of alpha-MSH- and ACTH-containing cells could be obtained well until 48 h after death. In the pars distalis the ability of ACTH-containing cells to take up stain increased during the period of post-mortem storage. In the youngest human fetus studied (15 weeks) only alpha-MSH-containing cells were found in the pars intermedia and no ACTH-containing cells were observed. In the other fetal pituitaries a distinct pars intermedia containing more alpha-MSH cells than ACTH cells was found. In the pars distalis of the fetuses more ACTH- than alpha-MSH-containing cells were observed. From birth to 19 years, progressively fewer alpha-MSH containing cells could be detected in the 'zona intermedia' and pars distalis, while in adults only a few such cells were found in either area. Irrespective of age, sex, cause of death or therapy, alpha-MSH-containing cells were found in all pituitaries throughout life. The number of ACTH containing cells gradually increased in the zona intermedia and pars distalis and reached a high adult level in the latter structure. In the pituitaries of seven anencephalics, no alpha-MSH-containing cells were present. The presence of alpha-MSH in the fetal pars intermedia, the change in the ratio of the alpha-MSH/ACTH cells during the course of development, and the absence of alpha-MSH in anencephaly all support the possibility that human fetal pituitary alpha-MSH is involved in both intrauterine growth and fetal adrenal function and thus also in parturition.

Adolescent↗
PubMed1978

The fetal brain and intrauterine growth.

The fetal brain stimulates intrauterine growth in man, rat and other species. Human congenital brain anomalies and experiments in rats indicate that the hypothalamus is the brain area responsible for this effect. The only factor found to stimulate intra-uterine growth was alpha-MSH. Various observations and experiments in rat show that stimulation of fetal somatic growth might indeed be a physiological function of alpha-MSH, while observations in the human fetus indicate that alpha-MSH might play a similar role in intra-uterine growth in man as well. Preliminary data in rat point to a similar function of this hormone in brain development.

Anencephaly↗
PubMed1976

Stimulation of intra-uterine growth in rat by alpha-melanocyte-stimulating hormone.

We have studied whether endogenous alpha-MSH has a function in stimulating intra-uterine growth in the rat. The approach used was to determine whether or not this hormone is present during the intra-uterine growth spurt, and if binding of endogenous foetal alpha-MSH by antibodies would inhibit this growth. Antibodies against alpha-MSH or ACTH 1-24, either purified or non-purified, induced immunofluorescence in the intermediate lobe of adult male control rats. Using purified anti-alpha-MSH, fluorescence appeared in the foetal intermediate lobe on day 18 of pregnancy, the day that biologically active MSH was first seen. A negative correlation was observed between the pituitary MSH content and foetal body weight only on day 19 of pregnancy. Injection of purified anti-alpha-MSH induced a drop in foetal body weight, but no effect on placental weight was observed. Purified anti-acth 1-24 had no effect upon body weight but caused an increase in placental weight. These results support our previous findings and indicate that endogenous MSH has a function in the stimulation of foetal growth.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Muscle mass and fat mass in relation to bone mineral density in very old men and women: the Framingham Heart Study.

Aim of the study was investigate the cross-sectional relationship between body composition and bone mineral density (BMD) in very old men and women. The study sample consisted of 504 women and 285 men, aged 72-93 yr, participating in examination 22 (1992-1993) of the Framingham Heart Study. Total body BMD, regional BMD, and soft-tissue body composition was measured by dual-energy X-ray absorptiometry. Both muscle mass and percentage body fat were positively associated with total body BMD in women. After adjustment for age, physical activity, smoking status, estrogen use, and thiazide use, BMD increased with increasing tertile of muscle mass (p = 0.007) and with increasing tertile of percentage body fat (p = 0.0001) in women. In men muscle mass, not percentage body fat, was positively associated with BMD. After adjustment for potential confounders, BMD remained associated with muscle mass only (p = 0.02). These results were similar for leg BMD and arm BMD. The study suggests that the influence of muscle and fat mass on bone mineral density is different between very old men and women.

Absorptiometry, Photon↗
PubMedDate not supplied

Waist circumference predicts clustering of cardiovascular risk factors in older South Africans.

OBJECTIVE AND DESIGN: A cross-sectional analytical study to determine the cardiovascular risk factor profile of older residents of fishing villages on the West Coast of South Africa, and to determine which anthropometric measures are associated with risk factors. SUBJECTS: A convenient community-based sample of 152 subjects of mixed ancestry aged 55 years and over was recruited door-to-door using an address list of age-eligible subjects provided by the local public health care clinics. METHODS: Cardiovascular relationships were investigated between (i) number of risk factors (hypertension, hypercholesterolaemia, diabetes) and body mass index (BMI), waist-to-hip ratio (WHR), and waist circumference; and (ii) continuous cardiovascular risk factor variables and physical activity, smoking, dietary intake, and 24-hour urinary sodium and potassium concentrations. RESULTS: The prevalence of hypertension ( > or =160/95 mmHg) was 74.3% (95% CI: 67.2 - 81.4%). Neither 24-hour urinary sodium nor potassium concentrations was associated with blood pressure (BP). Past, but not present, moderate-intensity physical activity, particularly that associated with occupation, was negatively associated with systolic BP (r = -0.24, P < 0.05). The prevalence of diabetes and hypercholesterolaemia (serum cholesterol > or = 6.5 mmol/l) was 24.6% (95% CI: 17.2 - 32%) and 40% (95% CI: 31.8 - 48.2%), respectively. The percentage of subjects with 0, 1, or 2 or more cardiovascular risk factors was 13.4%, 44.1% and 42.5%, respectively. Subjects with a waist circumference > or = 92 cm had a significantly higher number of cardiovascular risk factors than those with a waist circumference < 92 cm ( chi(2) = 9.29, P < 0.01), and this association remained significant even after controlling for age, sex and smoking (P < 0.05). Neither BMI tertiles according to sex, nor a BMI cut-point > or =30, was significantly associated with a clustering of risk factors. CONCLUSION: In a sample of older South Africans of mixed ancestry at high risk of cardiovascular disease, waist circumference measuring > or = 92 cm predicts clustering of risks factors, independently of BMI. This simple, population-specific reference value may provide a useful screening tool to identify at-risk individuals for targeted prevention for coronary heart disease and associated metabolic disorders.

Abdomen↗
PubMedDate not supplied

[Helminth species of goats in Germany].

The helminth fauna of the gastrointestinal tract of 25 and the respiratory organs and the livers of 6 German goats was qualitatively and quantitatively examined. One trematode species (Dicrocoelium dendriticum), 2 species of cestodes (Moniezia expansa and metacestodes of Taenia hydatigena) and 28 species of nematodes (24 in the gastrointestinal tract and 4 in the lungs) were recorded. Two goats were infested with Oestrus ovis larvae. The most prevalent species were Ostertagia circumcincta and Chabertia ovina (84% each), Ostertagia trifurcata and Oesophagostomum venulosum (76% each), Ostertagia pinnata and Trichostrongylus colubriformis (64% each), Trichuris ovis (60%) and Skrjabinema ovis and Trichuris globulosa (56% each). The highest mean worm counts were seen in goats infected with Skjabinema ovis (4003), Ostertagia circumcincta (2501), Trichostrongylus axei (1825), Trichostrongylus colubriformis (1578) and Nematodirus battus (1050). Totally, the goats did harbour more nematodes in the abomasum (3734) than in the small intestine (1707) or the large intestine (2343). The lungs were parasitized by Cystocaulus ocreatus, Muellerius capillaris, Neostrongylus linearis and Protostrongylus rufescens.

Animals↗