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Biomedical subjects

J Campbell

Publications and source records attributed to J Campbell.

At least 361 records · Page 20Linked to original sources
PubMed1983

Tension pneumocephalus after posterior fossa craniotomy: report of four additional cases and review of postoperative pneumocephalus.

Four cases of tension pneumocephalus after either posterior fossa craniotomy or translabyrinthine resection of acoustic neuroma with or without nitrous oxide anesthesia are described. Three of the operations were performed with the patient in the sitting position, and one was done with the patient in the lateral position. Of the three cases operated in the sitting position, no nitrous oxide was used at any time during anesthesia in one. Two patients failed to regain consciousness after the termination of anesthesia, and the other two developed the sudden onset of neurological symptoms 1 to 1.5 hours after the operation. In all cases computed tomography disclosed a large subdural collection of air. Re-exploration of the surgical wound or twist drill aspiration of the subdural air resulted in prompt recovery of neurological status in three patients, whereas the other patient's neurological status improved gradually without any specific treatment. The role played by nitrous oxide, the mechanisms by which air enters the intracranial space, the contributory factors, and the predisposing surgical conditions of tension pneumocephalus are reviewed and discussed. Dependent drainage of the cerebrospinal fluid, especially in a patient with coexisting hydrocephalus, seems to be the most important factor for the development of this complication.

Aged↗
PubMed1983

Clinical and technical aspects of continuous ERA recordings.

The recording of consistent ERA responses of maximum amplitude is dependent upon various clinical and technical factors. These are discussed in detail in relation to continuous patient monitoring. Particular attention is paid to electrode quality and care and techniques for chloriding and impedance measurement are described.

Adult↗
PubMed1983

Effect of 3-deazauridine on the metabolism, toxicity, and antitumor activity of azacitidine in mice bearing L1210 leukemia sensitive and resistant to cytarabine.

The effect of 3-deazauridine (DAUR) on the intracellular purine and pyrimidine nucleotide pools and on the metabolism of azacitidine (aza-CR) in L1210 cells, sensitive (L1210/0) and resistant (L1210/ara-C) to cytarabine (ara-C), was examined. The consequences of such a modulation were correlated with the therapeutic efficacy of this combination in mice bearing L1210 leukemia. In vitro and in vivo treatment of both L1210 sublines with DAUR produced a dose- and time-dependent reduction in the CTP and dCTP pools and an increase in the UTP pool. In addition to these changes in the pyrimidine nucleotide pools, DAUR produced a modest increase in the GTP pool and a marked expansion of the ATP pool in L1210/ara-C 12 hrs following in vivo drug treatment. These perturbations in nucleoside triphosphate pools were more pronounced in L1210/ara-C cells. Treatment of mice bearing L1210/ara-C with 100 mg/kg of DAUR reduced the CTP and dCTP pools in the leukemic cells by greater than 90% within 1-3 hrs after administration of the drug, with complete recovery of these pools occurring within 12 hrs. Fluctuation of the pyrimidine nucleoside pools after DAUR treatment was correlated with the subsequent increase in aza-CR metabolism and its incorporation into RNA and with the potentiation of the in vivo toxicity of aza-CR. In mice bearing L1210/0 or L1210/ara-C tumors, DAUR or aza-CR produced a less than or equal to 23% increase in life-span (ILS). Administration of aza-CR 3 hrs after DAUR, however, produced about an 80% ILS among mice bearing L1210/ara-C tumors, but no more than an approximately 20% ILS among mice bearing L1210/0 tumors. These data suggest that the therapeutic activity of the sequential combination of DAUR and aza-CR against mice bearing L1210/ara-C cannot be explained, per se, on the basis of the initial intracellular modulation of nucleotide pools, since DAUR affected these pools of the two tumors to approximately the same degree. What appears to be important, however, is that such a modulation by DAUR preferentially affected the metabolism of aza-CR in leukemic cells resistant to ara-C which are devoid of deoxycytidine kinase activity.

3-Deazauridine↗
PubMed1983

[Muscular ischemic pain. Effect of "training" after repeated performance of an experimental test].

Ischaemic muscle pain is a commonly used experimental stimulus in the evaluation of therapeutic analgesic measures. However, some doubts have recently been cast on the reliability of the results obtained with these methods. In this study, the reproducibility of Pain Threshold and Pain Tolerance time was investigated in 11 subjects who performed a tourniquet test on three occasions. Pain experienced between these two parameters was estimated using a Visual Analogue Scale. A statistically significant increase (p = 0.007) in Pain Tolerance was observed between the first and third tests. A non-linear relationship between perceived intensity of pain and time of painful muscular activity was similarly verified. These results were interpreted as a training effect. Caution on the experimental design of studies sequentially using ischaemic muscle pain methods is therefore recommended.

Female↗
PubMed1983

Effects of propranolol on blood lipids and lipoproteins in myocardial infarction.

The effects of propranolol on lipids and lipoproteins were investigated in survivors of a recent myocardial infarction who were enrolled in the double-blind Beta-Blocker Heart Attack Trial. Nonfasting serum samples were obtained in more than 2800 patients assigned randomly to either propranolol or placebo. The propranolol-treated group had high-density lipoprotein cholesterol levels 3-4 mg/dl less and triglyceride concentrations 30-40 mg/dl higher than the placebo group. These effects occurred in men and women in all age categories.

Adult↗
PubMed1982

Hepatitis and haemophilia therapy in Australia.

243 Australian haemophiliacs have been studied retrospectively over 4 1/2 years to assess the effect of treatment products on liver function and to determine the frequency of hepatitis-B markers in these patients. Commercial blood products are not used in Australia, and the patients were treated with products of blood from unpaid donors screened for hepatitis B surface antigen. Cryoprecipitate was the major treatment product, and only small amounts of factor VIII and IX concentrates were used. Despite the use of blood products obtained from entirely voluntary blood donors and the frequent use of single-donor packs of cryoprecipitate, markers of viral hepatitis were common in these haemophiliacs. Antibody to hepatitis B surface antigen was detected in 63% of the patients, and there were 66 cases of non-A, non-B hepatitis during the study. 29 of these episodes persisted for longer than 6 months. 13 patients (5.4%) had hepatitis B during the study; 2 patients remained HBsAg-positive for longer than 6 months. Abnormal serum aminotransferase levels were found in 34% of the patients; in 8% of patients these abnormalities persisted for more than 6 months.

Adolescent↗
PubMed1982

Comparative genotoxicity studies of ethyl carbamate and related chemicals: further support for vinyl carbamate as a proximate carcinogenic metabolite.

In vivo and/or in vitro mammalian cell systems were used to evaluate sister chromatid exchange (SCE) induction and gene mutagenesis effects following exposure to ethyl carbamate (urethane), vinyl carbamate, ethyl N-hydroxycarbamate, and 2-hydroxyethyl carbamate. Although ethyl carbamate caused dose-dependent increases in SCE when injected into mice, it was ineffective for inducing SCE and gene mutation (6-thio-guanine resistance) in Chinese hamster V-79 cells cultured with or without the addition of S9 enzyme mix during treatment. Chemical-specific patterns of genotoxicity were evident for the known or suspect metabolites under test: only vinyl carbamate consistently (in vivo and in vitro) revealed strong activity for the genetic endpoints. SCE induction levels of 5-8 times baseline were observed after animal or cell culture exposures to vinyl carbamate. Doses required to produce this effect in V-79 cells in the presence of S9 mix were approximately 100 times lower than those needed when S9 was absent. The extensive gene mutagenesis (approaching 600 mutants/10(6) survivors) noted was completely dependent upon the presence of S9 mix. These observations are consistent with current theory holding that vinyl carbamate is a metabolic intermediate of ethyl carbamate, and is converted to the ultimately reactive species (presumably, vinyl carbamate epoxide) which is responsible for ethyl carbamate carcinogenesis.

Animals↗
PubMed1982

Accumulation of poly-beta-hydroxybutyrate in Spirulina platensis.

Poly-beta-hydroxybutyrate has been identified in the cyanobacterium Spirulina platensis. The addition of reduced carbon compounds to the growth medium was not required for poly-beta-hydroxybutyrate accumulation. Poly-beta-hydroxybutyrate accumulated during exponential growth to 6% of the total dry weight and then decreased during the stationary phase.

Cyanobacteria↗
PubMed1982

Energy costs of walking in lower-extremity plaster casts.

The energy cost of walking with axillary crutches and each of three types of plaster casts (long, short, and cylinder) on the lower extremity was measured in twenty normal adult men. The knee and ankle joints were immobilized unilaterally in the neutral positions. Oxygen uptake was measured using a modified Douglas-bag technique. Heart rate, respiratory rate, and step frequency were telemetered from transducers that were attached to the subjects. When walking and bearing full weight on a cast without the use of crutches, the average rates of energy expenditure for subjects wearing the three varieties of casts did not significantly differ from the value for normal walking. Velocity, however, was reduced depending on the extent of immobilization. The average velocity of the subjects was fifty-six meters per minute in a long cast, sixty-four meters per minute in in a cylinder cast, and seventy meters per minute in a short cast, compared with seventy-eight meters per minute without immobilization of the limb. The subjects' average oxygen cost per meter was 0.24 milliliter per kilogram in a long cast, 0.20 milliliter per kilogram in a cylinder cast, and 0.19 milliliter per kilogram in a short cast, compared with 0.15 milliliter per kilogram for normal walking. Using a unilateral non-weight-bearing swing-through gait, the average rate of oxygen uptake for subjects wearing the three types of casts did not differ from the mean value without a cast (21.2 milliliters per kilogram per minute). All values were at least 60 per cent higher than the average for normal level walking.

Adult↗
PubMed1981

Birth centre confinement at the Queen Victoria Medical Centre. I. Obstetric and neonatal outcome.

A review of hte first 175 confinements at the Queen Victoria Medical Centre Birth Centre is presented. The design, structure and function of hte Birth Centre is described and the safety of the programme demonstrated. Seventy-four pregnancies (42%) accepted for Birth Centre confinement required transfer because of antepartum or intrapartum complications. There were satisfactory obstetric and neonatal outcomes in all pregnancies. The first year's experience has allowed a reassessment of the risk factors, which will permit greater use of the Birth Centre without any increases risk to mothers or babies.

Australia↗
PubMed1981

Growth hormone and metasomatotrophic diabetes: effects on insulin and proinsulin of serum and pancreas in dogs.

In normal fasting dog serum, the insulin: proinsulin molar proportion was 71:29%. In response to glucose infusion, the proinsulin proportion decreased. In the pancreas, the proinsulin proportion was lower than in serum. Growth hormone treatment for one day increased serum insulin sevenfold and proinsulin 18-fold. The proinsulin proportion increased to 49%. The growth hormone injections magnified the response to glucose infusion. The rise in serum insulin was 16 times the normal, proinsulin also rose but its proportion decreased. Growth hormone treatment for 6 days decreased pancreatic insulin to 5% and proinsulin to 46% of normal. In the permanent (metasomatotrophic) diabetes produced by the prolonged administration of growth hormone, serum insulin decreased in the proinsulin proportion increased. No rises in serum insulin nor proinsulin occurred following glucose infusion. In the pancreas, insulin and proinsulin were reduced to 1.6% and 8% of normal. The reduction in the immunoreactive insulin in the pancreas was more pronounced in the tail than in the head and body regions. The results indicate that in the state of augmented insulin secretion and hyperinsulinaemia produced by growth hormone and in the reduced insulin secretion and hypoinsulinaemia of metasomatotrophic diabetes, the proportion of proinsulin in serum is increased due to beta cell secretion containing a higher proportion of proinsulin than normal

Animals↗
PubMed1981

Nitrated polycyclic aromatic hydrocarbons: potent bacterial mutagens and stimulators of DNA repair synthesis in cultured human cells.

Ten polycyclic aromatic hydrocarbons (PAHs), viz. anthracene pyrene, chrysene, perylene, fluoranthene, benzo[a]pyrene, benzo[a]pyrene, benz[a]anthracene, benzo[ghi]perylene, benzo[k]fluoranthene, have been nitrated using concentrated nitric acid and the crude nitrated mixture examined for biological activity. All the nitro PAHs examined were mutagenic to Salmonella typhimurium in the absence of a rat liver preparation. Addition of Aroclor-1254 induced liver had little effect on mutagenicity. Mutagenic potency differed for the various nitrated mixtures with nitrated pyrene and nitrated fluoranthene the most potent and nitrated anthracene the least potent. Both frame-shift and base-substitution mutations were induced by the nitrated PAHs. The nitrated PAHs were also able to induce DNA repair synthesis in cultured HeLa cells in the absence of liver, indicating that these cells have the necessary enzymes to activate nitro PAHs. Potency again varied from compound to compound with nitrated pyrene appearing to be the most active. Isolation of individual components from the crude nitrated mixtures has not been carried out in this study. In view of the possible wide-spread distribution of nitrated PAHs in the environment further work is required to assess the carcinogenic potency of these compounds which possibly pose a risk to man.

Animals↗
PubMed1981

Infant botulism.

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Botulism↗