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Biomedical subjects

B Page

Publications and source records attributed to B Page.

At least 55 records · Page 3Linked to original sources
PubMed1997

Opercular jetting during fast-starts by flatfishes

When attacked by predators, flatfishes perform fast-starts that result in a rapid take-off from the ocean bottom on which they lie. High-speed video recordings of the blind side of flatfishes indicate that they expel a coherent jet of water from the blind-side opercular valve during take-off. Buccal pressure recordings in winter flounder (Pseudopleuronectes americanus) show that a buccal pressure pulse begins 0­20 ms before the beginning of the fast-start and has a range of mean magnitudes for three individuals of 1.6­10.7 kPa. We hypothesize that one function of the opercular jet in flatfishes may be to reduce the effects of Stefan adhesion. Stefan adhesion occurs as the fish lifts its head up rapidly from the ocean bottom, when water must flow into the space forming beneath the fish. Water viscosity opposes this rapid shear, and a suction pressure develops under the fish, making it more difficult for the fish to escape from the bottom. To estimate the magnitude of Stefan adhesion, we simulated fast-starts using a physical model in which a dead flounder was pulled upwards with an acceleration of 95 m s-2. Results from the physical model indicate that up to 35 % of the total force required to lift the head at 20 ms into the start can be attributed to Stefan adhesion. Despite this large adhesion force, previous work has shown that live flatfish do not show improved fast-start performance when Stefan adhesion has been eliminated by starting the fish from an open wire grid. Thus, live fishes are likely to be using behavioral mechanisms to reduce the adhesion force. Both the timing and location along the body of the opercular jet indicate that it is ideally suited to attenuate the effects of Stefan adhesion. Propping the body up on the median fins may also reduce adhesion by increasing the initial distance between the fish and the ocean floor.

Journal Article↗
PubMed1997

Influence of acute renal failure on FPIA rapid serum assay of midazolam and its main metabolite.

We recently developed a simple and fast assay technique, providing the possibility of monitoring of midazolam (M) during sedation. We compared HPLC vs FPIA for the measurement of the sum M plus alpha 1-hydroxymidazolam (OM), its main and pharmacologically active metabolite, in the serum of sedated ICU patients; this activity referred to as M-like. We identified certain patients in whom M-like activity appeared abnormally high in comparison with HPLC assays. Their common denominators were: long-term sedation with M, and seriously impaired renal function. Further, the conjugates of OM (OMG) accumulated in patients with acute renal failure could contribute to the sedation. We compared the metabolic and analytic behavior of M, OM, and OMG in 2 groups of sedated patients either presenting with normal renal functions (group 1) or with a picture of acute renal failure (group 2). Blood samples were assayed by HPLC and by FPIA and analysis was performed before and after hydrolysis of OMG. Before hydrolysis there was a dramatic accumulation of OMG in the patients of group 2, HPLC vs FPIA results were not different within group 1, while in group 2 the FPIA response exceeded that of HPLC. After hydrolysis, measurement by HPLC was greatly increased in group 2, in each group (vs HPLC) and from one group to another, the FPIA signal (the M-like activity) showed a significant increase. It would be important to take OMG into account as a coprotagonist in sedation whenever circumstances predispose to its accumulation.

Acute Kidney Injury↗
PubMed1996

Metoclopramide in trauma CT scanning: preventing emesis of oral radiographic contrast.

Vomiting of gastric contents is common among multisystem trauma patients and may cause significant morbidity. A study was conducted to examine whether metoclopramide (Reglan), an antiemetic and promotility agent, could decrease vomiting after administration of oral radiographic contrast in stable multisystem trauma patients undergoing computed tomography (CT) of the abdomen ("trauma CT patients"). The charts of 193 patients listed in the Duke Trauma Registry who underwent abdominal CT scanning from January, 1992 until February, 1993 were reviewed. The emergency department record was reviewed for documentation of vomiting, use of intravenous metoclopramide, and other potential confounders of vomiting such as age, pharmacologic paralysis, and head injury as measured by the Glasgow Coma Scale (GCS). Patients who received intravenous metoclopramide were six times less likely to vomit after administration of oral radiographic contrast than those who did not receive the drug. This effect increased to a twelvefold protective effect after correcting for age, pharmacologic paralysis, and GCS. These preliminary findings strongly suggest that routine use of metoclopramide may prevent vomiting of gastric contents after administration of oral radiographic contrast in trauma CT patients. A future prospective study is recommended to confirm these results.

Administration, Oral↗
PubMed1996

Comparison of high-performance liquid chromatography and polyclonal fluorescence polarization immunoassay for the monitoring of midazolam in the plasma of intensive care unit patients.

Midazolam (M) is used as an induction agent for anesthesia. The main metabolite is alpha-hydroxymidazolam (OM), which is pharmacologically active. Use of M for sedation is a recent application, rapidly gaining favor. Monitoring of the level of sedation is fundamental in that an excessive and prolonged effect is associated with the risk of complications. Thus, it was felt both necessary and useful to measure circulating M levels. We compared a high-performance liquid chromatography (HPLC) assay with fluorescence polarization immunoassay (FPIA) for the measurement of M in the serum of 138 sedated patients in the intensive care unit (i.e., 179 samples). Response of the OM was also assessed. The degree of crossover of the metabolite was between 76.8 and 32.7%. The equation of the regression line for sigma HPLC (i.e., the sum M + OM) versus FPIA was TDx = 1.1585 sigma HPLC + 143.42 (R = 0.966). The 95% confidence interval for the slope was 1.1551, 1.1619. The regression slope differed significantly from 1 (p < 0.001) and shows that FPIA measurements overestimated concentrations obtained by HPLC on the order of 19%. The discrepancy between the two techniques was all the more notable when concentrations were > 1,000 ng/ml. The relative selectivity of Abbott industrial reagent in terms of benzodiazepines leads to the identification of what might be called a midazolam-like (M-like) activity covering both M and OM. The development of a global FPIA method for measurement of this M-like activity in sedated patients provides a satisfactory solution to the question raised.

Adult↗
PubMed1996

Effects of four years' treatment with biosynthetic human growth hormone (GH) on body composition in GH-deficient hypopituitary adults.

Short-term trials of growth hormone (GH) substitution in hypopituitary adults have shown beneficial effects on body composition. To evaluate the long-term effects on body composition, we followed thirteen GH-deficient adults (GH < 6 mU/l following standard provocative tests) for 4 years of GH replacement. At yearly intervals, serum insulin-like growth factor I (IGF-I), body weight, body mass index (BMI), waist, waist-to-hip circumference ratio (WHR) and resting systolic (SBP) and diastolic blood pressure (DBP) were determined, and body composition was assessed using three independent methods: total body potassium (TBK), bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA). Compared to baseline, IGF-I levels increased significantly at 1 (p = 0.0001), 2 (p = 0.0004), 3 (p = 0.006) and 4 years (p = 0.002). Body weight and BMI changed minimally at 1, 2 and 3 years and increased significantly only at the fourth year (p = 0.012 and p = 0.0009, respectively) of GH therapy. Waist and WHR decreased significantly at 1, 2 and 4 years (waist: p = 0.0009, p = 0.0004, p = 0.049; WHR: p = 0.0025, p = 0.012, p = 0.047, respectively). Neither resting SBP nor DBP changed significantly. Fat-free mass (FFM) derived from TBK and BIA increased significantly at 1 (p = 0.004; p = 0.004), 2 (p = 0.003; p = 0.05), 3 (p = 0.005; p = 0.04) and 4 years (p = 0.02; p = 0.002). Using DXA, the increase in FFM was significant at 1 (p = 0.007) and 2 years (p = 0.008) but not at 3 and 4 years. Percentage body fat measured by TBK, BIA and DXA decreased significantly at 1 (p = 0.008; p = 0.003; p = 0.03), 2 (p = 0.018; p = 0.06; p = 0.049) and 4 years (p = 0.03; p = 0.002; p = 0.04). A rise in total body water, calculated from BIA, was observed at 1 year (p = 0.004) and was maintained throughout the treatment period. These data demonstrate that 4 years of GH treatment in hypopituitary adults is associated with sustained improvement in body composition.

Absorptiometry, Photon↗
PubMed1995

Outbreak of Pneumocystis carinii pneumonia in a renal transplant unit.

The charts for seven renal transplant recipients who developed Pneumocystis carinii pneumonia were reviewed. They included six men and one woman transplanted a mean of 150 days before the diagnosis of this infection. Six presented at least one episode of acute graft rejection. Cytomegalovirus pneumonia was diagnosed in six of the patients. All patients were treated with cotrimoxazole. Global mortality was 43%. In additional to the classic hypothesis of latent Pneumocystis carinii reactivation in immunocompromised hosts, this and previous reports of outbreaks strongly suggest either a person-to-person transmission or acquisition from the environment. Molecular typing of isolates could be of value in identifying the source of such outbreaks. Chemoprophylaxis should be more systematically administered to renal transplant patients, co-trimoxazole being the drug of choice.

AIDS-Related Opportunistic Infections↗
PubMed1995

Abnormal body composition and reduced bone mass in growth hormone deficient hypopituitary adults.

OBJECTIVES: The role of growth hormone in maintaining normal body composition and bone strength in adults has attracted much interest recently. We have assessed body composition and bone mass in GH deficient hypopituitary adults on conventional replacement therapy and compared them with matched controls. DESIGN AND SUBJECTS: A cross-sectional study of 64 growth hormone deficient hypopituitary adults (29 males and 35 females) on conventional replacement therapy and a large number of healthy control subjects matched for age, sex and body mass index (BMI). MEASUREMENTS: Skinfold thicknesses at two sites (triceps and subscapular), waist and hip girth circumferences were assessed by standard methods. Body composition was assessed using total body potassium (TBK), bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA). Bone mineral mass was assessed at the lumbar spine and the total body by DEXA. Not every patient and control participated in every measurement. RESULTS: Obesity was common in the hypopituitary patients; BMI (mean +/- SD) was 27.5 +/- 4.6 kg/m2 and body weight was 111.8 +/- 18.5% of the maximal ideal for height (P < 0.001). The sum of subscapular and triceps skinfolds was significantly higher in hypopituitary patients than in controls (men 46 + 15 vs 37 +/- 14 mm, P < 0.05; women 55 +/- 13 vs 47 +/- 17 mm, P < 0.05). Waist to hip circumference ratio was significantly greater in female hypopituitary patients than in matched controls but was not significantly different in men (men 0.94 +/- 0.07 vs 0.91 +/- 0.07, NS; women 0.84 +/- 0.09 vs 0.77 +/- 0.05, P < 0.001). The difference between patients and controls in the sum of skinfolds and the waist to hip ratio were present in non-obese (BMI < 26 kg/m2) subjects (21 patients and 32 controls). TBK corrected for body weight was significantly lower in hypopituitary patients (n = 44) than in controls (n = 31) (men 43.5 +/- 5.6 vs 50.1 +/- 5.9 mmol/kg, P < 0.003; women: 34.0 +/- 3.2 vs 40.6 +/- 5.3 mmol/kg, P < 0.0001). BIA-derived body water content (corrected for body weight) was significantly lower in hypopituitary patients (n = 56) than in controls (n = 57) (0.492 +/- 0.064 vs 0.545 +/- 0.067 l/kg, P < 0.0004). Percentage body fat derived from all the three methods was significantly higher in hypopituitary patients than in normal controls in both sexes (from TBK: men 34.7 +/- 9.4 vs 28.8 +/- 7.0%, P < 0.05; women 37.8 +/- 8.7 vs 30.4 +/- 9.7%, P < 0.01; from BIA: men 29.3 +/- 8.5 vs 23.2 +/- 8.4%, P < 0.01; women 34.6 +/- 8.1 vs 29.3 +/- 9.1% P < 0.01; and from DEXA: men 24.8 +/- 6.8 vs 20.4 +/- 6.1%, P < 0.05; women 38.9 +/- 7.9 vs 32.5 +/- 9.8%, P < 0.01). There was a significant difference between non-obese patients and controls in BIA-derived percentage fat in both sexes and in TBK-derived percentage fat in females only. Bone mineral density (BMD) of the lumbar spine in the L2-L4 region was lower in hypopituitary patients than in controls (men 1.116 +/- 0.129 vs 1.311 +/- 0.131 g/cm2, P < 0.0001; women 1.001 +/- 0.122 vs 1.131 +/- 0.138 g/cm2, P < 0.001). Spine BMD was also reduced in hypopituitary patients compared to the young adult and age and weight matched reference data. Total body BMD was significantly lower in patients than in controls (men 1.186 +/- 0.102 vs 1.250 +/- 0.080 g/cm2, P < 0.05; women 1.080 +/- 0.077 vs 1.149 +/- 0.073 g/cm2, P < 0.005). CONCLUSIONS: Hypopituitary adults on conventional therapy have abnormal body composition with increased fat content, reduced body water content and reduced bone mineral mass.

Adipose Tissue↗
PubMed1995

Immunoglobulin E levels in relationship to HIV-1 disease, route of infection, and vitamin E status.

Our recent studies have demonstrated that in early HIV-1 infection, elevation of plasma immunoglobulin E (IgE) levels precedes the decline of CD4 cell count and is influenced by vitamin E status. In order to further investigate the role of IgE elevation in HIV-1 infection, we determined IgE levels in HIV-1-seropositive and -seronegative intravenous drug users (IDUs) (n = 38), in relationship to cellular and humoral immune function, liver enzymes, and vitamin E status. To examine the possible impact of the route of HIV-1 infection on IgE levels, comparisons between the cohorts of the HIV-1-seropositive and -seronegative IDUs and homosexual men (n = 45) were also conducted. All HIV-1-seropositive participants had significantly higher (P = 0.003) IgE levels than the HIV-1-seronegative subjects. The HIV-1-seropositive IDUs, moreover, demonstrated significantly higher (P = 0.01) IgE levels than HIV-1-seropositive homosexual men, despite similar CD4 cell counts. Stepwise regression analysis was used to evaluate the possible variables contributing to the IgE variation. HIV-1 status (P = 0.0009), intravenous drug use (P = 0.014), CD8 cell counts (P = 0.0001), plasma level of vitamin E (P = 0.006), and alcohol intake (P = 0.047) were significant, accounting for 71% of the IgE elevation. These findings suggest that IgE may serve as a sensitive marker to reflect the evolution of HIV-1 disease in individuals from different risk groups.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Erythropoietin for autologous transfusion. Use in a case of severe anemia with allo-immunization].

In view of the transfusional risks of viral transmission (notably HIV), autologous transfusion is increasingly used; it is often the only possible type of transfusion. A 42-year-old woman with lupus erythematosus, chronic renal failure and triple cardiac valve disease demanding surgery was admitted for multifactorial severe anaemia. Treatment with erythropoietin (8000 units/day) iron replenishment, corticosteroids and polyvalent immunoglobulins was initiated. The patient was operated upon in April 1990. A preoperative cell-saver autotransfusion was performed during surgery. The postoperative period was uneventful. Homologous transfusion was not necessary. In this case where homologous transfusion was ruled out, erythropoiesis stimulated by erythropoietin enabled autotransfusion and cardiac surgery to be performed.

Adult↗
PubMed1994

AIDS knowledge, occupational precautions, and public education activities among law enforcement officers and first responders.

A survey on AIDS was administered within a large, southern California jurisdiction to law enforcement officers and first responders (paramedics, firefighters). Respondents had accurate knowledge about AIDS but several incorrect perceptions about HIV transmission; a substantial proportion believed that HIV could be contracted from casual contact. AIDS training was not frequent. Self-assessment of HIV risk was medium to high risk in one-third of respondents, and was largely attributable to fear of occupational exposure. Appropriate precautionary professional practices were adopted at low frequencies, with respondents adopting preventive measures less than 50% of the time on 7 of 10 measures. Seventeen percent reportedly received requests for HIV/AIDS education from members of the public, which is incongruous with law enforcement officers' and first responders' demonstrated level of knowledge about HIV transmission. It was concluded that improved educational programs on HIV/AIDS are needed for law enforcement officers and first responders to increase the use of occupational precautions in the field, and to improve the accuracy of public AIDS education activities conducted by these professionals.

Acquired Immunodeficiency Syndrome↗