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Biomedical subjects

G G Harrison

Publications and source records attributed to G G Harrison.

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

Zinc, calcium, and magnesium concentrations in milk from American and Egyptian women throughout the first 6 months of lactation.

Effects of stage of lactation, nutrient intake, and cultural differences on the composition of human milk were examined during the first 6 mo of lactation in American and Egyptian women. In both population groups zinc levels in milk decreased from 1 to 6 months of lactation. American women supplemented with Zn had higher levels of Zn in their milk than did unsupplemented American or Egyptian women. Concentrations of calcium and magnesium were not significantly different in milk of American and Egyptian women except at month 6 of lactation. Ca levels in milk of both population groups increased from 1 to 2-3 mo of lactation and then decreased at 6 mo; Mg concentrations increased from 1 to 3 mo and then reached a plateau. Similarities in the longitudinal decrease observed in Zn levels of milk in Zn supplemented and unsupplemented subjects suggested physiological regulation.

Adult↗
PubMed1988

Halothane decreases albumin and transferrin synthesis: studies in the isolated, perfused rat liver and in the intact rat.

Isolated perfused rat livers exposed to 1.5% halothane (equivalent to 1.35 MAC) in O2/CO2 or to O2/CO2 alone produced urea, as well as albumin and transferrin (both measured by immunodiffusion), at constant rates during a 4.25-h perfusion. Urea production did not differ in the two treatment groups, but halothane depressed albumin and transferrin synthesis 43% and 45%, respectively. Intact rats were also exposed to halothane, after which albumin synthesis was measured by the (14C)carbonate technique. The minimum halothane concentration required to insure sufficient relaxation for ventilation was selected and ranged from 1.0 to 1.5%. Measurements were made in control rats not exposed to halothane (group I) and in halothane exposed rats immediately after 1 h of anesthesia (group II), 24 h after the start of 1 h of anesthesia (group III), and immediately after 1/2 h of anesthesia preceded by a 1-h exposure 24 h earlier (group IV). Single exposures to halothane (groups II and III) resulted in a decrease in albumin synthesis immediately or 24 h later that did not differ significantly from controls (group I). However, halothane given twice to rats at 24-h intervals (group IV) reduced their mean albumin synthesis rate to half that of controls. The early onset and constancy of halothane depression of export protein synthesis by isolated, perfused livers may reflect a response to halothane itself, rather than an effect resulting from the accumulation of halothane metabolites. Similarly, reduction of albumin synthesis in intact rats immediately after a second halothane exposure may indicate a response to halothane, rather than to halothane metabolites.

Albumins↗
PubMed1988

The effects of calcium channel blocking drugs on halothane initiation of malignant hyperthermia in MHS swine and on the established syndrome.

We have investigated in malignant hyperthermia susceptible swine in vivo the effects on halothane initiation of the MH syndrome and on the established syndrome of five calcium channel blocking drugs--nifedipine, nisoldipine, diltiazem, verapamil and flunarazine. Nifedipine alone caused attenuation of halothane-initiated malignant hyperthermia to the extent of blocking onset of the syndrome in 29% of animals for the 60 minute period of exposure. In the face of the established malignant hyperthermia syndrome, all the drugs tested were therapeutically completely ineffective.

Anesthesia, General↗
PubMed1987

Acute calcium homeostasis in MHS swine.

To elucidate a pathogenesis for the reduction in bone calcium content observed in MHS individuals, we studied the acute calcium homeostasis of MHS swine. This was achieved by the serial measurement, with a calcium selective electrode, of calcium transients in Landrace MHS (five) and control Landrace/large white cross MH negative (five) swine following IV bolus injection of calcium gluconate 0.1 mmol X kg-1--a dose which induced an acute 45 per cent increase in plasma ionised calcium. Experimental animals were anaesthetised with ketamine 10 mg X kg-1 IM, thiopentone (intermittent divided doses) 15-25 mg X kg-1 (total) IV and N2O/O2 (FIO2 0.3) by IPPV to maintain a normal blood gas, acid/base state. The plasma ionised calcium decay curve observed in MHS swine did not differ from that of control normal swine. Further it was noted that the induced acute rise in plasma ionised calcium failed to trigger the MH syndrome in any MHS swine. It is concluded that the mechanisms of acute calcium homeostasis in MHS swine are normal. An explanation for the reduction in bone calcium content observed in MHS individuals must be sought, therefore, through study of the slow long-term component of the calcium regulatory process. In addition, the conventional strictures placed on the use, in MHS patients, of calcium gluconate are called in question.

Anesthesia, General↗
PubMed1986

Fatty acid composition of mature human milk of Egyptian and American women.

Fatty acid composition of mature human milk of rural Egyptian and American women was determined by gas-liquid chromatography. Milk of Egyptian women contained significantly higher percentages of capric, lauric, myristic, linoleic and arachidonic acids, saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA). Conversely, milk of American women contained higher percentages of stearic and oleic acids, total unsaturated fatty acids, and monounsaturated fatty acids. The PUFA:SFA ratio in Egyptian samples was 0.54 +/- 0.18 compared to 0.47 +/- 0.22 in American samples. Increased percentages of medium-chain SFA in Egyptian milk suggested increased mammary gland lipid synthesis. Analysis of Egyptian diets indicated high-carbohydrate and low-fat intakes may have resulted in limited availability and incorporation of dietary fatty acids into milk triglycerides. Thus, increased percentages of medium-chain SFA observed in Egyptian milk may reflect mammary gland synthesis in an attempt to maintain lipid concentrations in milk.

Adult↗
PubMed1986

The screening of atracurium in MHS swine.

The potential role of atracurium besylate as a trigger or attenuator of the malignant hyperthermia syndrome was tested in six MHS Landrace swine. Animals were tested for susceptibility and then exposed to atracurium given as an i.v. bolus both alone and concomitantly with 2% halothane. In no instance could the syndrome be triggered by atracurium nor did it convincingly attenuate the syndrome when triggered by halothane.

Animals↗
PubMed1986

A feasibility study of a new approach to clinical radiosensitisation: hypothermia and hyperbaric oxygen in combination with pharmacological vasodilatation.

It is proposed that hyperbaric oxygen fails in the clinical situation due to a high proportion (greater than 33%) of hypoxic cells in human tumours. The means of overcoming this problem are reviewed. Additional to hyperbaric oxygenation, moderate hypothermia (30 degrees C) to allow redistribution of oxygen in the tumour is proposed. A system of externally controlled intravenous anaesthesia has been developed for the single-subject hyperbaric cylinder. Pharmacological vasodilatation is induced in the anaesthetised patient who is then fluid loaded and cooled. Initial single-sensitising treatments are advocated. Twenty-nine patients with advanced mouth cancer have completed a course of this treatment, of whom five of nine were free of disease after 2 years and 10 of 21 at 1 year, with three intercurrent deaths. Fifteen have experienced local failure. This approach would appear to be practical, safe and promising.

Anesthesia, Intravenous↗
PubMed1986

Single-dose relative biological effectiveness and toxicity studies under conditions of hypothermia and hyperbaric oxygen.

An approach to using hyperbaric oxygen with radiation in a clinical situation has been described in the preceding paper in this issue. To ascertain whether there might be a change in the relative biological effectiveness of radiation on normal mammalian tissue treated under conditions of hypothermia and hyperbaric oxygen, the acute reaction to radiation of pig skin was studied. A single dose enhancement ratio at the erythema reaction level of 1.4 +/- 0.08 was obtained when compared with irradiation at normal body temperature in air. We studied also a series of antioxidant enzymes in rat liver and lung after exposure to hypothermia and hyperbaric oxygen. Enzyme changes were such as to combat oxygen toxicity which might develop as a result of the pre-treatment.

Animals↗
PubMed1985

Porphyrinogenicity of etomidate and ketamine as continuous infusions. Screening in the DDC-primed rat model.

The porphyrinogenicity of etomidate and ketamine administered as continuous i.v. infusions was screened in the DDC-primed rat model of latent variegate porphyria. Ketamine produced no change from control in 5-aminolaevulinate synthase (ALAs) activity and haem intermediate production in either untreated or DDC-primed rats, and would appear to be safe for use in the patient with genetic porphyria. Etomidate, while producing no significant changes in these parameters in untreated rats, caused a statistically significant 47% increase in hepatic ALAs activity with a corroborative 85% increase in coproporphyrin and a 40% increase in protoporphyrin content, in DDC-primed rats. On these grounds, etomidate must be regarded as potentially porphyrinogenic when administered as a continuous infusion for total i.v. anaesthesia.

5-Aminolevulinate Synthetase↗
PubMed1985

Height-weight tables.

The concept of "desirable" weight derives from analyses of data in which relative body weight is correlated with mortality experience. "Ideal" or lowest-risk weights vary for different populations, and vary for the same population at different times and in relation to different causes of mortality. An ideal weight cannot be identified at a point in time for a person or persons differing from the groups on which desirable-weight tables were based. This fact, plus the limitations of existing tables and databases, has prompted some observers to suggest abandoning the concept of ideal weight. The recent publication of updated data for the U.S. population and updated height-weight tables based on actuarial data have focused attention on this issue. In addition, several studies have attempted to relate body weight to mortality in defined populations. At the same time, some studies have found significant relationships between overweight and mortality whereas others have not.

Actuarial Analysis↗
PubMed1984

Recommended therapeutic guidelines for professional weight control programs.

At the present time there are no established guidelines to serve as standards for the operation of weight control programs. This increases the possibility that some programs may be conducted in a fashion that is unethical, jeopardizes patient health, and lacks credibility. As a first step toward developing such standards, a panel was organized by the International Congress on Obesity to describe minimum recommended features of professional weight control programs. The present report served as a supporting document for the summary statement and describes recommended guidelines for the treatment of obesity encompassing diet, physical activity, and behavior modification with psychological support. The role of drugs and surgery is not considered in this report. For the average patient it is suggested that three components of therapy--diet, exercise, and behavioral/psychological support--be prescribed together since they are closely interrelated, interdependent and mutually supportive.

Behavior Therapy↗
PubMed1984

Workshop on methods for characterizing human obesities. Purposes and types of classifications.

The data base describing human obesities has expanded rapidly in the recent past, and the heterogeneity of this set of conditions is becoming clearer. Nevertheless, our lack of adequate understanding both of etiology and of functional consequences inhibits our ability to devise classifications which are therapeutically useful. A first step is the delineation of criteria for detailed characterization of obesity. In devising such criteria, it will be useful to bear in mind the purposes of classification schemes (etiologic, functional, therapeutic, prognostic) and the extent to which our existing understanding and conceptual categories (both scientific and cultural) direct our thinking.

Cystic Fibrosis↗