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Biomedical subjects

R H Johnson

Publications and source records attributed to R H Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1983

Mortality associated with alcoholism in New Zealand.

Rates of mortality were determined in patients attending an alcoholic assessment centre. The study group comprised 1068 patients, studied for a mean of 1.5 years after referral. A total of 50 deaths occurred, being four times the expected death rate in the general population. Significantly increased mortality rates were found for deaths from cirrhosis, other digestive disease, cardiovascular disease, neoplasms, trauma and alcoholism. In 15 patients death was due to definite alcohol-related causes.

Adolescent↗
PubMed1983

Effects of ethanol on plasma catecholamines and norepinephrine clearance.

Plasma catecholamines were measured in nine men after they had drunk either 0.5 or 1 ml/kg ethanol. Ethanol was found to induce a dose-dependent rise in plasma norepinephrine concentrations. Epinephrine concentrations were also raised in the initial intoxication phase. To determine whether ethanol raises plasma norepinephrine through increased release or decreased clearance (Cl), we infused norepinephrine into eight male subjects with and without prior ethanol, each subject acting as his own control. During infusions after ethanol, norepinephrine concentrations rose higher, and the mean circulatory Cl of norepinephrine was reduced from 76 to 47 ml/kg/min. This was associated with a prolongation of norepinephrine t 1/2 from 1.7 to 2.05 min. No significant difference in circulatory input of norepinephrine was found between infusions with and without ethanol. These results indicate that ethanol consumption increases plasma norepinephrine by reducing its circulatory Cl.

Adult↗
PubMed1983

Do elderly patients with an excessive fall in blood pressure on standing have evidence of autonomic failure?

1. Blood pressure, heart rate and plasma catecholamine responses were examined in two groups of elderly subjects distinguished by blood pressure responses to standing. Subjects in the control group showed a fall of less than 15 mmHg in systolic blood pressure on standing; subjects in the orthostatic hypotension group had falls of more than 20 mmHg systolic and 10 mmHg diastolic blood pressure on standing. 2. The heart pressure response on standing showed no significant difference between the two groups. 3. The orthostatic hypotension patients had lower plasma noradrenaline concentrations than the control patients (P less than 0.01) in the supine position, but during 10 min standing there was no significant difference in noradrenaline levels between the groups, and the percentage increase of noradrenaline levels in the orthostatic hypotension group was greater (P less than 0.05) than in the control group. 4. In the supine position, diastolic blood pressure was higher (P less than 0.05) in the orthostatic hypotension group than in the control group. 5. We conclude that impairment of baroreceptor function is not involved in most cases of orthostatic hypotension in the elderly, nor is there reduction of sympathetic nervous activity. We suggest that mechanical changes or adrenoreceptor dysfunction are more likely to be important factors in orthostatic hypotension in the elderly.

Aged↗
PubMed1983

The present status of canine parvovirosis.

Results from studies performed by the authors and by other workers, have greatly increased the knowledge of canine parvovirus. The authors review the situation with particular reference to virology, epidemiology, pathogenesis, pathology and immunoprophylaxis.

Age Factors↗
PubMed1983

Release of glucagon in male alcoholics with vagal neuropathy.

There is evidence supporting involvement of the parasympathetic nervous system in the control of glucagon secretion. We have investigated the possible role of vagal neuropathy in alcoholics as a cause of alcoholic hypoglycemia. Slow infusions of insulin (2.4 U/hr) were carried out in ten male alcoholics, four with and six without evidence of vagal neuropathy, and in six male controls. The fall in blood glucose levels and the rise in serum glucagon levels in the alcoholics with or without vagal neuropathy were not significantly different from controls. We conclude that vagal neuropathy in alcoholics has no effect on the glucagon response to hypoglycemia.

Adult↗
PubMed1983

Serum concentration of clonazepam and the therapeutic effect of the drug.

The effect of other anticonvulsants (phenytoin, phenobarbitone and primidone) on serum clonazepam concentrations has been studied. Serum clonazepam concentrations were measured in 47 epileptic patients in whom a dose of clonazepam (3 mg or 6 mg) was added to existing therapy. 44 patients were receiving other anticonvulsants; 3 were not receiving any other medication. Patients on low doses of other anticonvulsants showed high clonazepam concentrations. Patients on multiple therapy with high doses of other anticonvulsants showed excessive side-effects on clonazepam and low serum clonazepam concentrations. We conclude that other anticonvulsants may reduce serum clonazepam concentrations and therefore that clonazepam is best given alone.

Adolescent↗
PubMed1983

The effect of diphenylhydantoin on metabolic and growth hormone changes during and after exercise.

Metabolic and human growth hormone responses to exercise were investigated in six normal healthy subjects on two occasions with and without an oral dose of diphenylhydantoin (500 mg). Serum diphenylhydantoin concentrations were similar in all subjects and were just below the accepted therapeutic range for epileptic patients. There was no significant difference in blood lactate, pyruvate or glucose concentrations with diphenylhydantoin. Plasma free fatty acids, and blood glycerol and total ketone concentrations were greater after exercise following diphenylhydantoin. Significantly greater concentrations of human growth hormone occurred during exercise with diphenylhydantoin. Further investigation of the mechanisms by which diphenylhydantoin alters lipolysis and human growth hormone release would be of value as these metabolic and hormonal effects could influence exercise tolerance in athletics and other pursuits.

Administration, Oral↗
PubMed1983

Effects of ethanol ingestion on thirst and fluid consumption in humans.

To investigate the effects of ethanol on thirst, fluid intake was measured in 24 normal subjects for 3 h after consumption of 1.0 g/kg ethanol, with or without administration of a vasopressin analogue (DDAVP) before ethanol ingestion. Fluid consumption was reduced in subjects receiving DDAVP, suggesting that thirst after ethanol is largely secondary to dehydration due to inhibition of vasopressin release. Further, the effects of ethanol on salt-load-elicited thirst and fluid consumption in normal subjects were studied using intravenous hypertonic saline infusions. Subjects acted as their own controls and received 0.5 or 1.0 ml/kg ethanol 30 min before infusions on one day and an equal volume of fluid on another day. During infusions after ethanol, subjects experienced thirst later and at higher osmolalities. They also drank less immediately after infusions with prior ethanol ingestion. The relationship between thirst score and plasma osmolality was shifted to higher osmolalities by ethanol. Thus, although ethanol progressively causes thirst secondary to dehydration, it has a direct inhibitory effect on the thirst response to osmotic stimulation.

Deamino Arginine Vasopressin↗
PubMed1982

Deficient catecholamine release as the basis of orthostatic hypotension in pernicious anaemia.

A patient with peripheral neuropathy and orthostatic hypotension was found to have pernicious anaemia. Symptoms improved after vitamin B12 replacement therapy. Insulin tolerance testing showed that the patient lacked catecholamine, heart rate, and sweating responses to hypoglycaemia. This indicates that pernicious anaemia may cause orthostatic hypotension owing to failure of noradrenaline release.

Aged↗
PubMed1982

Effect of ethanol ingestion on plasma vasopressin and water balance in humans.

The effects of 75 ml ethanol ingested over 60 min on plasma osmolality (Posmol) and plasma vasopressin (PAVP) in four normal subjects were studied. In the 1st h of the investigation PAVP fell, then rose, even though plasma ethanol levels were still rising. The rise in PAVP was preceded by a rise in Posmol corrected for the influence of ethanol. The fall in PAVP was followed by an increase in free water clearance and a decrease in urine osmolality, while the later rise in PAVP was followed by a decrease in free water clearance (CH2O) and a rise in urine osmolality. The relationship between PAVP and Posmol was then studied during intravenous (iv) hypertonic saline infusion in five subjects. The results were compared with those from a second infusion in the same subjects after ingestion of ethanol (0.5 ml/kg). Ethanol reduced vasopressin release in response to iv hypertonic saline infusion, and this correlated with a reduced decrease in CH2O. We conclude that ethanol inhibits PAVP release by decreasing the response of the osmosodium receptors to changes in plasma tonicity.

Adult↗
PubMed1982

The effectiveness of an electro-ionizing toothbrush in the control of dentinal hypersensitivity.

The object of the investigation was to test the value of the 3M Brand Electro-Ionizing Toothbrush in the treatment of dentinal hypersensitivity. Eighty-eight volunteers were divided into three groups, each using different methods: (I) stannous fluoride dentifrice and 3M brush without a battery; (II) stannous fluoride dentifrice and 3M brush with a 1 1/2 volt battery; and (III) strontium chloride dentifrice and 3M brush without a battery. The volunteers brushed their teeth for 3 minutes twice a day for 12 weeks using one of the three test agents. The subjects were tested at weeks 0, 2, 4, 8 and 12 by means of a cold water spray quantitated by a temperature probe. All three groups experienced improvement and by week 12 Groups II and III displayed much less sensitivity than did Group I. At the end of the 12 weeks the subjects were questioned as to benefit of treatment. The questionnaire revealed that stannous fluoride with the ionizing brush provided significantly greater relief than did the stannous fluoride alone.

Adult↗
PubMed1981

Prescribing patterns for epilepsy.

All prescriptions for anticonvulsants written over a four month period for patients in the Wellington area were identified. Of 1479 patients receiving anticonvulsants, 139 were suspected of receiving medication for conditions other than epilepsy. The prevalence of treated epilepsy in Wellington is 4.1 per 1000 population. Thirty-eight percent of patients were on multiple anticonvulsants, which compares favourably with reports of excessive polypharmacy in Europe. However, there was excessive reliance on standard anticonvulsant doses, given at frequent intervals regardless of probable rates of metabolism. Failure of compliance, as assessed by the time intervals between collection of drugs, was shown by 21 percent of patients.

Adult↗
PubMed1981

Cell lines from sheep and cattle blood.

A simple and reproducible method of establishing cell lines from the blood of sheep and cattle is described. Buffy coat cells were allowed to adhere to plastic culture flasks in media containing 20 per cent autologous plasma overnight. The fluids were then replaced with growth medium supplemented with non-inactivated foetal calf serum, lamb serum or autologous serum. Ovine cell lines were established with any of the serum supplements but bovine cell lines established more readily if unheated autologous serum was used.

Animals↗