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Biomedical subjects

M White

Publications and source records attributed to M White.

At least 289 records · Page 16Linked to original sources
PubMed1992

A portable target controlled propofol infusion system.

A portable target controlled infusion system for propofol has been developed based on a Psion hand-held microcomputer and the Ohmeda 9000 syringe pump. The system uses a pharmacokinetic model which describes the distribution and elimination of propofol to achieve and maintain any selected target blood concentration. Target blood concentrations of 1 micrograms/ml, 3 micrograms/ml and 5 micrograms/ml were selected in laboratory trials and the cumulative volumes delivered by the Psion system each minute were compared with the theoretical output calculated by the pharmacokinetic model. The results obtained showed that the computer system delivered volumes which were always within 2% of the theoretical values. This system offers a convenient and simple method of maintaining anaesthesia using propofol.

Anesthesia, Intravenous↗
PubMed1992

Analyses of 95 first-trimester spontaneous abortions by chorionic villus sampling and karyotype.

PURPOSE: Our purpose was to determine the incidence of chromosomal aneuploidy in first-trimester pregnancy losses using chorionic villus sampling (CVS). STUDY DESIGN: All patients presenting for CVS with no fetal cardiac activity were offered CVS. RESULTS: Cytogenetic results were completed in 95 of 96 cases (99%). Eighty-three percent of the karyotypes were aneuploid. The 16 euploid fetuses had no excess of females. CONCLUSION: CVS is the most reliable method of determining the karyotype of spontaneously aborted fetuses. The incidence of aneuploidy is much greater than in previous reports that analyzed passed products of conception. CVS should be offered to women who present with first-trimester spontaneous abortions.

Abortion, Spontaneous↗
PubMed1992

The relationship between a nutritional index and acute physiology score in critical illness.

Prognostic indices derived from available physiological data (SAPS), complex nutritional and biochemical tests (PNI), grip strength and serum albumin were calculated in 16 critically ill patients receiving intravenous nutrition over a six week period. The aim was to compare these independently derived prognostic indices, to assess their response to feeding, and to determine suitability for use in Irish intensive care units. Mean SAPS (7.6 +/- 0.92), PNI (3.1 +/- 0.29), serum albumin (30.3 +/- 1.03 g/l) and grip strength (17.9 +/- 1.3%) were all suggestive of an "at risk" group. Significant associations were found between the accepted SAPS index and both PNI (r = 0.6, p < 0.001, n = 35) and grip strength (r = -0.68, p < 0.001, n = 44) but not with serum albumin. No consistent improvement was seen in response to feeding in any of the derived indices. The close correlation between prognostic indices derived from either physiological, nutritional or grip strength data in this study and the failure of prognostic indices to improve during hyperalimentation would support a common mechanism, e.g. endogenous mediators, for metabolic and physiological disturbance in critical illness. It suggests that the role of hyperalimentation is supportive rather than therapeutic and re-iterates the importance of managing underlying disease processes. Simple grip strength may be a useful alternative to complex nutritional indices.

Critical Illness↗
PubMed1992

Babesia bovis: analysis of and preliminary vaccination studies with a defined infected erythrocyte membrane binding antigen.

Murine monoclonal antibodies (MAB) were produced against the 'beta' fraction of Babesia bovis. A MAB, W11C5, selected on the criterion of its staining of erythrocytes infected with B. bovis, was purified. The antigen identified by MAB W11C5 was extracted from B. bovis infected erythrocytes by affinity chromatography and used in a vaccination trial to test its vaccine efficacy against homologous B. bovis infection in splenectomized calves. The vaccinated group showed significantly different parasitaemias from the control group and it was concluded that the B. bovis antigen 11C5 induced a protective immune response when used as a vaccine. This antigen should be synthesized using recombinant DNA techniques to determine its efficacy and suitability as a commercial vaccine against B. bovis infection.

Animals↗
PubMed1992

Typing of HLA-DQA1 and DQB1 using DNA single-strand conformation polymorphism.

The technique of single-strand conformation polymorphism (SSCP), which is capable of distinguishing DNA sequence variability, was adapted to the identification of the HLA-DQA1 and DQB1 alleles. Eight DQA1 alleles and 12 DQB1 alleles were distinguished by amplifying the second exon of the genes in the presence of radioactive deoxynucleotide, denaturing the products with heat, and separating the single strands by electrophoresis in nondenaturing gels. For DQA1, it was possible to distinguish the eight alleles with standard bis-acrylamide or with a Hydrolink gel matrix. Twelve DQB1 alleles were identified by a protocol employing a combination of oligohybridization and SSCP using products amplified by specific DQB1 primers.

Alleles↗
PubMed1992

Cryptococcal meningitis: outcome in patients with AIDS and patients with neoplastic disease.

A retrospective analysis of 41 patients with cryptococcal meningitis and AIDS or neoplastic disease was done. Patients with AIDS were younger and predominantly male; they had a shorter duration of prior illness, higher initial serum cryptococcal antigen titers, and lower initial cerebrospinal fluid white blood cell counts than those with neoplastic disease. The median overall survival for patients with AIDS was 9 months compared with 2 months for those with neoplastic disease (P = .004). Seventy-eight percent of patients with AIDS and 43% of those with neoplastic disease were cured or improved 6 months after diagnosis (P = .039). Toxicity from amphotericin B and flucytosine was similar for both groups. One patient with AIDS relapsed. Multivariate predictors of survival included headache (P = .007) and an AIDS diagnosis (P = .009). Examination of outcomes for other opportunistic infections associated with AIDS and other immunosuppressive illness may distinguish prognostic features for different patient populations.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Induction of anaesthesia with propofol using a target-controlled infusion system.

Sixty patients premedicated with temazepam were allocated randomly to receive an infusion of propofol designed to achieve and maintain a target blood concentration of 3, 4 or 5 micrograms.ml-1. Induction time was measured from the start of infusion to loss of verbal contact. The success rate of inducing anaesthesia within 3 min of achieving the target concentration was 40% when the predicted target concentration was 3 micrograms.ml-1, 75% when the predicted target was 4 micrograms.ml-1 and 90% when the target was 5 micrograms.ml-1. There were no significant differences between the three groups for time to loss of verbal contact in patients who were induced successfully within 3 min. There were significant reductions in arterial pressure 3 min after achieving the target concentrations within the groups but not between them. The frequency of apnoea and pain on injection was small in all groups. Selecting a target concentration of 5 microgram.ml-1 would successfully induce anaesthesia in the majority of patients premedicated with temazepam without major haemodynamic or respiratory side effects.

Adolescent↗
PubMed1992

Translation of an instrument. The US-Nordic Family Dynamics Nursing Research Project.

Translation of a research instrument questionnaire from English to another language is analyzed in relation to principles involved, procedures followed, and problems confronted by nurse researchers from the US-Nordic Family Dynamics Nursing Research Project. Of paramount importance in translation are translation equivalency, congruent value orientation, and careful use of colloquialisms. It is important to recognize that copyright guidelines apply in the translation of an instrument. Approaches to solving instrument translation problems are discussed.

Copyright↗
PubMed1992

Reducing and managing restraints in long-term-care facilities.

OBJECTIVE: To evaluate a management system designed to improve staff adherence to a federal regulation that stated restrained residents should be released, exercised, and repositioned every 2 hours. DESIGN: A delayed intervention, controlled, cross-over design with three phases. During phase one, baseline, the length of intervals that residents remained in restraints was monitored. The intervention was implemented at site A in Phase two while site B remained in baseline. During Phase three, the intervention was replicated at site B. SETTING: Two long-term care proprietary nursing facilities. PATIENTS: Sixty-three physically restrained residents in the two facilities. INTERVENTION: The intervention was a system of restraint release using colored pads corresponding to specific hours. The management rule was that the resident should be on a different colored pad every 2 hours. Staff had to lift residents to place the pad, and the colors made the system easy for supervisors to check. MAIN OUTCOME MEASURES: Checks by research personnel by black light and invisible ink, to detect movement of the knot tying the restraints. RESULTS: During the baseline phase, the majority of residents at both sites were inappropriately restrained longer than 2 hours (site A: 54.1%; site B: 60.1%). The percentage of residents restrained over 2 hours was significantly reduced during the intervention phase to 13.9% (site A) and 19.4% (site B). Three weeks after the end of the intervention, inappropriate use of restraints remained low, 14.2%, but rose to 47.7% after another 3 weeks. CONCLUSION: The management system is an effective way to increase the consistency with which nursing-home staff release and reposition restrained residents.

Aged↗
PubMed1992

Activities of antifolate, antiviral, and other drugs in an immunosuppressed rat model of Pneumocystis carinii pneumonia.

The efficacy of antifolate, antiviral, and other drugs was compared in an experimental model of pneumocystosis. Sulfamethoxazole (SMX) administered alone in doses of greater than or equal to 60 mg/kg/day was highly effective in treatment and prophylaxis. Low (less than or equal to 15 mg/kg/day) doses of SMX showed limited, dose-related anti-Pneumocystis carinii activity in therapy but were more effective in prophylaxis. The dihydrofolate reductase (DHFR) inhibitors trimethoprim (TMP), pyrimethamine, and trimetrexate exhibited little anti-P. carinii activity when administered alone and did not enhance the efficacy of SMX; the effects of the DHFR inhibitors could not be related to the dose or the concentration in serum. These data suggested that the rat model is an excellent system for studying the anti-P. carinii activity of sulfonamides but is of limited value in studying DHFR inhibitors. The antiviral drugs azidothymidine, dideoxyinosine, inosine pranobex (Isoprinosine), amantadine, and acyclovir displayed little or no activity against P. carinii; however, azidothymidine did not impair the efficacy of SMX or TMP-SMX. These results supported the clinical practice of giving antiviral agents together with antifolate drugs to patients infected with human immunodeficiency virus and suggested that the beneficial effects of antiviral agents on the occurrence of pneumocystosis are due mainly to their effects on the virus or the host immune response. In contrast to the antiviral drugs, 9-deazainosine, a nucleoside analog with antiprotozoal properties, demonstrated marked activity against P. carinii which was related to dose and route of administration. These data raised the possibility that anti-P. carinii activity is a general property of purine nucleosides and suggested that further exploration of this class of compounds might lead to clinically useful agents.

Animals↗
PubMed1992

Treatment of experimental pneumocystosis: review of 7 years of experience and development of a new system for classifying antimicrobial drugs.

Over a 7-year period, we analyzed 261 dose regimens of antimicrobial drugs in the treatment and prevention of Pneumocystis carinii pneumonia in an immunosuppressed rat model. These compounds ranged from drugs in clinical use to newly synthesized agents. Drug efficacy was expressed as the magnitude of the reduction in median P. carinii cyst or nucleus counts on a scale ranging from inactive (less than 5-fold) to very markedly active (greater than or equal to 1,000-fold). The classification system was reproducible and allowed drugs studied at different times to be compared with each other. The system demonstrated a hierarchy of anti-P. carinii activity not only among classes of compounds but also among individual members of a drug class. Sulfonamides, sulfones, and diamidines were the most active agents; some purine nucleosides and nitrofurans also showed promising activity; and most antiparasitic, antifungal, antibacterial, and antiviral drugs were inactive. We conclude that this classification system represents a simple, quantitative method of comparing the activities of antimicrobial drugs against P. carinii. Information gained from this system should be helpful in developing new anti-P. carinii compounds and establishing standard procedures for their evaluation.

Animals↗
PubMed1992

Munchausen syndrome by proxy.

This study examined the indicators of possible presence of Munchausen Syndrome by Proxy (MSBP) in pediatric inpatients discharged against-medical-advice (AMA), in cases transferred to another hospital, and in regular discharges. In a two-year period, there were fourteen AMA discharges and twenty-four transfer cases. These were compared to a randomly selected sample of forty-one regular discharges occurring during the same time period, matched for age, sex and pediatric service. The records were scored for the presence or absence of six MSBP characteristics, which had been developed from a review of MSBP literature. The findings indicated a suspicion for MSBP in 64 percent of the AMA cases, 8 percent of the transfer cases, and none in regular discharges. The findings suggest that AMA discharges need to be examined for the possible presence of MSBP.

Depressive Disorder↗
PubMed1992

Spinal muscular atrophy: new thoughts on the pathogenesis and classification schema.

We have established the first prospective, collaborative study of spinal muscular atrophy, the second most common neuromuscular disease of childhood. One hundred and forty-one patients have been evaluated on at least four occasions over a 3-year period. The patients have been grouped by age of onset, as well as by function at the time of initial evaluation. The muscle strength of 96 patients aged 5 years or older was evaluated at 6-month intervals using a fixed myometry system. The new observations made are: (1) The present classification schema is not valid; for example, 49 patients with onset of weakness before 6 months of age (type I or Werdnig-Hoffmann disease), whose life span is said to be only 2 to 4 years, participated in the study and are 4 months to 31 years of age. (2) Thirty-seven patients were evaluated over an 18-month period. None lost strength during this time but four lost function. Although the period of observation was short, the results suggest that the loss of function in patients with spinal muscular atrophy might be explained by a process other than cell death that allows patient strength to be maintained and simultaneously prevents the motor unit from achieving its normal adult potential.

Adolescent↗
PubMed1992

Early transplantation for patients with diabetic nephropathy.

Renal transplantation is often the preferred renal replacement modality for individuals with the complex problem of diabetic nephropathy. Referral to a transplant program before renal replacement therapy is needed allows patients an opportunity to make treatment decisions as well as offer the advantages of early transplantation. In addition to routine post-transplantation surveillance, health care after transplantation is directed towards prevention and management of diabetic sequelae.

Diabetic Nephropathies↗