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Biomedical subjects

J Hamer

Publications and source records attributed to J Hamer.

At least 19 recordsLinked to original sources
PubMed1979

Plasma progesterone and luteinising hormone levels in cattle after synchronisation of oestrus with dinoprost.

The plasma levels of progesterone and luteinising hormone (LH) were monitored in a group of cattle after pretreatment with two injections of 25 mg dinoprost. Close groupings of preovulatory LH peaks were observed and the possible significance of this is discussed. Based on the findings of this study, supporting evidence is provided for the timing of insemination after injection of cattle which have been synchronised for oestrus with dinoprost.

Animals↗
PubMed1979

Meningioma of the foramen magnum presenting as subarachnoid haemorrhage and cerebellar haematoma.

An unusual case of a posterior fossa meningioma which caused subarachnoid haemorrhage (SAH) and cerebellar haematoma is presented. The possible causes of tumoral bleeding and the surprising clinical course are discussed in the context of the few similar cases reported in the literature. The importance of cerebral CT scan ning in SAH without angiographic demonstration of an aneurysm or angioma is emphasized.

Adult↗
PubMed1979

Relation of plasma aldosterone concentration to diuretic treatment in patients with severe heart disease.

To assess the relation of hyperaldosteronism and potassium depletion to the intensity of diuretic therapy we have measured plasma aldosterone by radioimmunoassay and total exchangeable potassium by radioisotope dilution in 24 patients when they were stable at the end of their preparation for cardiac operation. Some patients required intensive frusemide therapy to reach an optimal state for operation and many showed hyperaldosteronism. Plasma aldosterone was significantly related to daily dose of frusemide (r=0.77). Depletion of total exchangeable potassium expressed in terms of predicted weight was significantly related to plasma aldosterone (r= -0.64). The reduction in total exchangeable potassium is interpreted as chiefly related to loss of lean tissue mass from the wasting that leads to cardiac cachexia, but evidence is presented on the basis of measurements of extracellular fluid volume as sulphate space (20 patients) of entry of sodium into the cells which may indicate a true cellular potassium loss. Although plasma potassium is usually easily maintained with oral potassium supplements or aldosterone antagonists, we postulate that intensive diuretic therapy in severe heart disease may provoke hyperaldosteronism which accentuates potassium loss and may contribute to wasting and to intracellular potassium depletion in critical tissue, such as myocardium.

Adult↗
PubMed1979

[Influence of combined moderate arterial hypoxaemia and moderate hypovolaemic hypotension on cerebral blood flow and cerebral oxidative and energy metabolism in the dog (author's transl)].

The influence on total cerebral blood flow, cerebral metabolic rates for oxygen, carbon dioxide, glucose, lactate and pyruvate and on cerebral grey matter content of glucose, lactate and pyruvate and high energy phosphate compounds of combined moderate reduction in cerebral perfusion pressure (CPP) and moderate arterial hypoxaemia was studied. Individually arterial hypoxaemia and arterial hypotension of the same degree would neither impair autoregulation of cerebral blood flow nor cerebral oxygen availability. Four groups of 10 dogs each were studied under control conditions (group I), with reduction of CPP to 70 mm Hg (group II), with reduction of paO2 to 45 mm Hg (group III) or with a combination of these degrees of hypotension and hypoxaemia (group IV) after steady states of 30 min duration. Cbf was elevated by 40% in group III (p less than or equal to 0.01), CMRO2 was reduced significantly in group IV (p less than or equal to 0.01, CMR lactate was raised significantly in all three experimental groups (p less than or equal to 0.01). All other data were not significantly different from values in control animals. Cerebral tissue lactate content was elevated significantly in groups II to IV as compared to controls (less than or equal to 0.05); changes in cerebral tissue content of glucose and energy rich phosphate compounds were not statistically significant. From the seemingly normal cerebral blood flow in hypotensive-hypoxaemic dogs it is concluded that autoregulation of cerebral blood flow has become ineffective because of vasodilatation consequent upon arterial hypoxaemia. Reduction of CMRO2 in this group points to metabolic insufficiency and to relative cerebral hypoperfusion, but since changes in cerebral content of high energy phosphate compounds were not significant, severe tissue hypoxia may be excluded. The increase in cerebral tissue lactate content is attributable to increased glycolytic activity known from hypotensive and hypoxaemic states. The present investigation suggests that in patients with hypoxaemia and hypotension, brain function may be endangered by a similarly marked change of circulatory and metabolic parameters.

Animals↗
PubMed1978

Cerebral glucose and energy metabolism, cerebral oxygen consumption, and blood flow in arterial hypoxaemia.

The influence of moderately reduced arterial oxygen tension (aPO2 of about 45 Torr) on the metabolism and the blood flow of the brain was tested in 20 anaesthetized, artificially ventilated normotensive, normocapnic beagle dogs. It is demonstrated that the decrease in systemic oxygen delivery to the brain is countered by an appropriate increase in flow (CBF being 60.3 ml/100 g min at normoxia and 84.5 mg/100 g min in hypoxaemia) which maintained the cerebral oxygen consumption unchanged (CMRO2 3.80 versus 3.32 ml/100 g min). The cortical tissue content of energy-rich phosphates such as ATP, ADP, AMP, and phosphocreatine was also found to be unaltered. Neuropathological examinations excluded any hypoxic cell damage. This reactive vasodilatory reaction of the cerebral vessels is apparently a sensitive regulatory process which protects the brain against marked oxygen lack. However, a normal carbohydrate metabolism is not restored by this cerebrovascular mechanism. For, significantly increased CMRlactate (0.32 versus 1.46 ml/100 g min) indicated raised cerebral glycolysis, and the tissue metabolites of glucose suggested an increased glycolytic flux in the brain. It is concluded that in moderate arterial hypoxaemia, which is not uncommon in clinical practice, cerebral blood flow plays an effective homeostatic role in preventing a disturbance of the energy metabolism of the brain.

Adenine Nucleotides↗
PubMed1978

Removal of craniopharyngioma by subnasal-transsphenoidal operation.

Two children with transsphenoidal microneurosurgical extirpation of a craniopharyngioma are presented. The value of this relatively new surgical approach is demonstrated, and the indication for transsphenoidal microsurgery in selected cases of craniopharyngioma is discussed in relation to the hitherto few similar case reports in the pertinent literature. The subnasal-transsphenoidal approach is the operative method of choice in purely or mainly intrasellar craniopharyngioma. This operation is also indicated in combined intra- and suprasellar craniopharyngiomas where the solid portion of the tumor is located intrasellarly and where the cystic part extends suprasellarly. In addition, the transsphenoidal operation may be a safe procedure in emergency cases with rapid loss of vision provided that the craniopharyngioma does not have a purely supra- and parasellar expansion. The esseential prerequisite for transsphenoidal neurosurgery in craniopharyngioma is an enlarged sella turcica. The importance of computerized cranial tomography with regard to preoperative differential diagnosis of a predominantly solid or cystic lesion and to postoperative control of radical tumor excision is emphasized. It is assumed that 25% of all patients with craniopharyngioma could benefit from transsphenoidal operation.

Brain Neoplasms↗
PubMed1978

Comparison of digoxin and medigoxin in normal subjects.

1 The properties of a recently introduced digitalis glycoside, 4-beta-methyl digoxin (medigoxin) were compared to those of a standard digoxin preparation. Using a radioimmunoassay (RIA) technique, serial plasma levels were recorded for 8 h following a single oral dose in five fasting volunteer subjects, and urinary glycoside elimination was measured for 4 consecutive days after dosage by use of a modification of the RIA method. 2 It was found that this RIA was suitable for plasma level measurement of both digoxin and midigoxin by reference to appropriate standard curves. Comparison of the plasma level profiles of these two drugs showed that medigoxin was very rapidly absorbed with peak levels occurring within 15--30 min, while digoxin produced peak levels after 45--75 min. The area under the plasma level-time curve produced by medigoxin was also consistently greater than that produced by digoxin, even though the medigoxin dose used was smaller. Quantitative comparison of these areas after adjustment to compensate for differing doses showed that medigoxin is considerably more biologically available than digoxin under study conditions (ratio 1.6 +/- 0.25:1), and comparison of quantitative urinary elimination suggested that medigoxin is eliminated in the urine to a lesser extent than digoxin and therefore it undergoes more metabolism and/or hepato-biliary elimination.

Adult↗
PubMed1978

Effects of selective and non-selective beta-adrenergic blockade on coronary dynamics in man assessed by rapid atrial pacing.

The effects on coronary dynamics of propranolol and atenolol were studied in 12 patients undergoing cardiac catheterisation for suspected coronary artery disease. Myocardial blood flow was measured using the coronary sinus continuous thermodilution technique. Data were obtained immediately after drug administration and during rapid atrial pacing. The immediate effects were similar for both drugs. A significant reduction in heart rate was accompanied by a small reduction in myocardial oxygen consumption. Changes in coronary sinus flow induced by rapid pacing were closely related to changes in tension-time index. This relation was not modified by propranolol or atenolol. Neither propranolol nor atenolol therefore has significant coronary vasoconstrictor properties. Cardioselectivity appears to be unimportant with respect to beta-adrenergic blockade and the coronary circulation.

Adult↗
PubMed1977

[Distal ulnar nerve compression at the wrist. "Loge de Guyon" and "deep ulnar branch" syndrome (author's transl)].

The distal non-traumatic ulnar nerve compression syndrome can be dividded into two types: -i) the proximal (paralytic) type caused by compression in the "Loge de Guyon", with involvement of both the superficial sensory and the deep branch, including the motor branch to the hypothenar muscles, and, ii) the distal, more common, purely motor type (the deep ulnar branch syndrome) with paresis of the interossei and the adductor pollicis, and less commonly of the hypothenar muscles. Whereas the proximal type has various causes, particularly pressure and occupational trauma, the distal type is almost exclusively the result of extra-neural ganglion cysts. An accurate diagnosis is made possible by electromyography and nerve conduction studies. The sensory nerve action potentials, distal motor latency to the hypothenar and adductor pollicis muscles, and the corresponding muscle action potentials after nerve stimulation are pathologically altered, according to the type of lesion. Although spontaneous recovery may occur, operation is the treatment of choice, provided that simple pressure palsy is eliminated.

Action Potentials↗