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Biomedical subjects

W Hamilton

Publications and source records attributed to W Hamilton.

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

Methemoglobinemia and hemolytic anemia associated with Campylobacter jejuni enteritis.

A 7-week-old infant with methemoglobinemia, hemolytic anemia, and inadequate weight gain was found to have a Campylobacter jejuni gastrointestinal tract infection. Known etiologies of methemoglobinemia such as oxidative drug exposure, deficiency of NADH-methemoglobin reductase, and hemoglobin M disorder were excluded. The patient had a twin brother (probably identical) who had neither methemoglobinemia nor stool cultures positive for C. jejuni. The twin essentially served as an experimental control, making other environmental or genetic causes of methemoglobinemia unlikely in the patient. Both the methemoglobinemia and the C. jejuni infection responded to adequate treatment with erythromycin. The association of a C. jejuni infection with methemoglobinemia is discussed in light of previous associations of enteritis and methemoglobinemia in infants.

Anemia, Hemolytic↗
PubMed1987

Streptococcus pneumoniae endocarditis.

We have reported a case of Streptococcus pneumoniae endocarditis involving the aortic valve of a 61-year-old alcoholic man. Antibiotic therapy with vancomycin sterilized the blood and valve, but aortic valve replacement was required for progressive congestive heart failure resulting from a ruptured valve leaflet.

Aortic Valve↗
PubMed1986

Sex hormone priming prior to the combined hypoglycaemia test.

The insulin hypoglycaemia test (IHT) was performed on 3 groups of short stature children. One group was unprimed with sex steroid hormones, a second group received 17 beta-oestradiol, while a third group received testosterone. The dosage of insulin was adjusted to produce a nadir in blood glucose of reversible 1 mmol/L. When this level is achieved plasma growth hormone (GH) responses less than 10 mU/L are not improved by either priming procedure. It is suggested from the data that there is no place for a diagnosis of a partial GH deficiency state. When the IHT is combined with Gn-RH and TRH infusion the data derived may indicate GH-RH deficiency alone or additionally a CRF deficiency. Alternatively a pituitary insensitivity to these releasing substances or a pituitary synthetic failure of all trophic hormones may be adduced. Unless a releasing hormone is deficient and the pituitary is shown to be able to respond to its synthetic analogue, treatment with the available analogues will fail to give the desired clinical response.

Adolescent↗
PubMed1985

[Intraoperative monitoring using transesophageal 2-dimensional echocardiography].

Currently used monitoring techniques, such as measurements of blood pressure and heart rate, provide incomplete information about cardiac function during surgery. Invasive monitoring like intraoperative pulmonary artery pressure measurement with flow-directed balloon catheters may be more sensitive to detect cardiac instability, but they are associated with potentially fatal complications such as dysrhythmias and pulmonary artery rupture. In search of a more informative and yet safe intraoperative hemodynamic monitoring system, we have investigated the use of 2-D transoesophageal echocardiography (TEE). So far more than 400 patients were studied by TEE for up to 12 hours during elective surgery without any complications. High quality recordings of the left ventricle (LV) could be obtained in 87% of all patients. On the basis of the results presented below, we believe that TEE holds three fundamental advantages over the existing monitoring systems: it is inherently safer than intravascular measures, it allows direct assessment of LV filing, and it provides direct information on global and regional LV wall motion.

Abdomen↗
PubMed1983

Edge-light pupil cycle time and optic nerve disease.

Edge-light pupil cycle time is a quantitative measure of pupil reaction to light, dependent on the functioning of the afferent arm of the pupillary reflex arc. It has been used as an objective assessment of optic nerve function in various neuroophthalmic diseases. In this study, pupil cycle times were determined on 60 eyes of 30 normal subjects, and a mean value of 814 ms with an upper limit of normal at 935 ms was established. The average difference between the two eyes was 34 ms, and the upper limit of normal was 79 ms. Pupil cycle times were then performed on ten eyes with optic atrophy, and all ten (100%) had abnormal values. Nine patients with multiple sclerosis were tested and abnormal cycle times were found in 15 of 18 eyes (83%). Five additional patients with questionable diagnoses were tested, and all but one had abnormal pupil cycle times. A discussion of pupil reactions in optic nerve disease is presented, and the value of edge-light pupil cycle time as a quantitative measure of nerve function is assessed.

Adult↗
PubMed1982

Filamentary keratitis.

We treated 19 eyes of 16 patients who had filamentary keratitis associated with various diseases of the cornea with 5% sodium chloride eyedrops, administered three to four times daily. Filaments associated with acute or traumatic diseases of the cornea responded in all nine cases, with rapid resolution of symptoms and signs (usually within one week). Filaments associated with keratoconjunctivitis sicca responded more slowly (average response time, four weeks); in one of nine cases (11%), the treatment failed. One case of essential filamentary keratitis responded within four weeks. The overall success rate was 95% (18 of 19 cases), with 17 cases (89%) showing dramatic improvement within four weeks.

Humans↗
PubMed1981

Turner's syndrome associated with growth hormone deficiency.

11 out of the 13 children with Turner's syndrome currently attending our endocrine clinic were investigated for possible growth hormone deficiency. The parents of two of the 13 children refused permission for these studies. One child had inadequate hypoglycaemia and the test was not repeated. Six of the ten children with adequate hypoglycaemia had an adequate growth hormone response to hypoglycaemia, while 4 children did not. This contradicts several previous studies on children with Turner's syndrome, which have reported normal growth hormone responses to provocative tests. In the normal population approximately one in 15 has an inadequate growth hormone response to hypoglycaemia.

Adolescent↗
PubMed1980

Influence of surgery on plasma propranolol levels and protein binding.

The influence of surgery and anesthesia on perioperative plasma propranolol levels was studied in 25 hyperthyroid and five euthyroid patients undergoing thyroidectomy. Propranolol levels fell markedly after surgery as a consequence of poor drug administration in the immediate postoperative period due largely to patients' nausea and inability to swallow. Propranolol was not detectable in the plasma of three hyperthyroid patients 8 hr after surgery. When propranolol was given through a nasogastric tube, propranolol levels were satisfactory throughout. Compared with preoperative levels, in all patients there was a two- to threefold rise in total and free propranolol levels 24 hr after surgery, suggesting decreased hepatic clearance of propranolol. The degree of plasma protein binding of propranolol had also increased on the day after surgery, leading to a 30% reduction in propranolol free fraction. Surgery and anesthesia greatly influence the handling of propranolol in the perioperative period.

Absorption↗
PubMed1980

Failure of naloxone to reduce manic symptoms.

The authors conducted a double-blind placebo-controlled study in which patients with a wide range of manic symptoms were administered 20 mg of naloxone subcutaneously. Naloxone failed to improve manic severity, activation-arousal, or elation-grandiosity for intervals up to 3 hours. Global nurse ratings of mania did not improve over an 8-hour period. The authors suggest that the question of endorphin involvement in mania has not been resolved and recommend clinical studies with longer acting oral narcotic antagonists such as naltrexone.

Affective Disorders, Psychotic↗
PubMed1980

Propranolol dosage in thyrotoxicosis.

Eighteen thyrotoxic patients receiving chronic treatment with propranolol (160 mg/day) were studied to determine the relationship between plasma propranolol concentration and drug effect. There was a considerable interindividual variability in both the plasma propranolol steady state concentration and the degree of beta-adrenergic blockade. The plasma propranolol steady state concentration correlated significantly with both beta-adrenergic blockage and weight change but not with the degree of subjective improvement. In a group of 40 patients, including 10 severely thyrotoxic patients, who had the dosage of propranolol titrated objectively preoperatively to bring about a greater than 25% reduction in exercise heart rate at the end of a dosage interval, no case of thyroid storm was encountered. Many patients, the younger and severely thyrotoxic in particular, require doses in excess of 160 mg/day to achieve this degree of beta-adrenergic blockade.

Adolescent↗
PubMed1979

The effect of cancer on the spin-lattice relaxation time of mouse blood and tissue.

Spin-lattice relaxation time measurements were made on the muscle, heart, kidneys, spleen, liver, brain and blood of both normal mice and those injected with Sarcoma-180. As well as a marked increase in the relaxation time of the tumour itself, mice injected with Sarcoma-180 showed a rise in the kidney relaxation time, along with blood relaxation times which were often either above or below the range found in normal mice. Correlation coefficients for the relaxation times of the various organs were calculated and found to be very sensitive to the physiological state of the animal. For healthy mice, the correlations were reasonably high, but even mild stress decreased the correlations, whilst the presence of cancer almost completely destroyed the correlations. These findings are all consistent with the hypothesis that cancer affects the water regulatory system of the animal as a whole.

Animals↗
PubMed1979

Growth hormone response to prostaglandin E2.

C-AMP causes release of growth hormone from the pituitary. Prostaglandin increases pituitary adenylate cyclase and C-AMP and therefore acts like a growth hormone-releasing hormone. Using PGE2 (30 microgram per kilo body weight) given intravenously we have demonstrated that in no case was there a growth hormone response to insulin hypoglycaemia when PGE2 failed to evoke a response. However in 6 of 18 patients unresponsive to insulin hypoglycaemia a significant rise in growth hormone was obtained from PGE2. We argue that in these 6 patients hypothalamic unresponsiveness to hypoglycaemia must be operative whereas PGE2 acting directly at pituitary level is likely to have caused the release of preformed growth hormone from the pituitary. Administration of PGE2 does not cause hypoglycaemia but rather a slight rise in the plasma glucose level. Thus the risk of brain damage which is inherent in the insulin hypoglycaemia test is avoided.

Adolescent↗
PubMed1978

Essential fatty acid deficiency in neonates: inability to reverse deficiency by topical applications of EFA-rich oil.

Correction of essential fatty acid deficiency by transcutaneous absorption of topically applied EFA-rich oil has been reported. We measured serum EFA levels in two groups of neonates receiving fat-free total parenteral nutrition: nine control patients after 16 and 25 days of TPN, and six patients before and 12 days after beginning cutaneous application of 100 mg/kg/day of linoleic acid as sunflower seed oil. Progressive biochemical EFA deficiency occurred in all but one of the control patients. Of the six patients receiving 100 mg/kg/day of linoleic acid, one patient with mild deficiency improved, but progressive EFA deficiency occurred in the other five patients. Serum EFA levels were also measured in four patients following 76 days of TPN and daily application of high doses of topical safflower oil, all of whom had severe biochemical EFA deficiency. The topical application of EFA-rich oil cannot be assumed to be uniformly effective in reversing or preventing EFA deficiency. The transcutaneous absorption of essential fatty acids must be documented by appropriate measurements of EFA in serum lipids.

Administration, Topical↗