Search PubMed⌕ Search

Biomedical subjects

T D Hockaday

Publications and source records attributed to T D Hockaday.

At least 127 records · Page 7Linked to original sources
PubMed1976

Increased sensitivity of in vivo platelet aggregation in rabbits after alloxan or streptozotocin.

In 14 rabbits previously injected intravenously with alloxan (dose 75-150 mg/kg) with subsequent hyperglycaemia, intra-arteriolar aggregation of platelets at the sites of small standardized electrical injuries to cerebral cortical vessels showed an increased sensitivity (P is less than 0.001) to application of adenosine diphosphate (ADP) in animals anaesthetized with either urethane or Pentothal. Intravenous injection of streptozotocin (10 rabbits, dose 30-200 mg/kg) was not followed so regularly by hyperglycaemia but even so many of these animals also showed increased sensitivity to ADP. After neither alloxan nor streptozotocin did the increased sensitivity correlate with the dose of agent used, the time between its injection and ADP testing, or changes in the rabbit's body weight. Again, ADP sensitivity did not correlate with the degree of hyperglycaemia, hyperketonaemia or hyperlactacidaemia. There was no rapid change in ADP sensitivity after i.v. injection of glucose to produce hyperglycaemia in normal rabbits, nor after parenteral or topical administration of insulin. Use of a removable skull capsule allowed serial observations on individual animals and these, together with observations on rabbits injected first with alloxan and later with daily insulin, showed reversibility of the increased ADP sensitivity by regular insulin injection for at least 5 days; this effect did not depend upon return of blood glucose levels to normal. In cross-perfusion experiments the increased ADP sensitivity was found to be dependent upon a blood factor for such sensitivity was shown by the head of a normal rabbit perfused with blood from a diabetic trunk. The results did not exclude a contribution of a mural factor to the results in intact animals after alloxan. The results are in keeping with in vitro observations of increased sensitivity to ADP of platelet aggregation in diabetic patients and demonstrate that such an effect holds within living blood vessels, as well as providing a model for further experiment.

Adenosine Diphosphate↗
PubMed1975

Migraine and reporoductive hormones throughout the menstrual cycle.

In a clinical survey the relation between migraine and menstruation was studied in 142 otherwise healthy women. In 24, onset of migraine coincided with the year of menarch. Of the 138 patients in whom onset of migraine predated the menopause, there were only 13 in whom attacks occurred regularly, and only, just before or during menstruation; in a further 11 attacks occurred regularly in relation to menstruation and at other times. Those with menstrually related migraine were more likely to have onset of migraine at menarche, to have associated weight gain and breast discomfort as part of a periodic syndrome, and to show improvement during pregnancy. There appeared no clear pattern of change at the menopause. In a study of reproductive hormones, blood was collected daily throughout a menstrual cycle from each of 8 women with menstrually related migraine, 6 with menstrually non-related migraine, and 8 healthy headache-free controls. Plasma levels of follicle-stimulating hormone (F.S.H.), luteinising hormone (L.H.), prolactin, oestrogen, and progesterone were measured in all. Plasma-testosterone was measured in 8 migraine patients. Mean plasma oestrogen and progesterone levels were significantly higher in migraine patients than controls for most of the menstrual cycle, with the most striking differences found in the late luteal phase for progesterone. No significant difference was found between the menstrually related and non-related patients for these or the other hormones measured. Mean plasma-prolactin levels were lower in migraine subjects than controls, but the difference was not significant. Mean plasma F.S.H. and L.H. levels were similar in both migraine and control groups. Plasma-testosterone levels were within the range for normal in the 8 migraine patients studied. No specific hormone changes were associated with the occurrence of a migraine attack, nor did rising or falling levels, or greater increments of change over given cycle phases, appear important in provoking attacks.

Adolescent↗
PubMed1975

Plasma testosterone and prolactin in the menstrual cycle.

Daily hormonal studies during nine ovulatory menstrual cycles showed that plasma prolactin and testosterone concentrations fluctuated randomly and independently. Mean plasma testosterone levels were found to be higher during the 7 days before and after the mid-cycle LH peak when compared to the premenstrual phase (P less than 0-01). No correlation was found between daily levels of prolactin and those of LH, FSH, oestrogen or progesterone and no correlation was seen between peaks of prolactin and testosterone or mean prolactin and testosterone levels. The lack of correlation between blood levels of prolactin and testosterone during the menstrual cycle suggests that prolactin is unlikely to have any direct controlling influence on the cyclical nature of testosterone production observed during ovulatory menstrual cycles.

Adult↗
PubMed1975

Plasma concentration of gonadotrophins, oestrogens and progesterone in thyrotoxic women.

Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), oestrogen and progesterone were measured daily in 15 thyrotoxic women in the reproductive age for 28 to 30 consecutive days before commencement of therapy and for a similar period following restoration of the euthyroid state. Five of these patients had secondary amenorrhoea whilst the other 10 had hypomenorrhoea. Twelve healthy volunteer eythyroid women of similar age and parity, with no history of menstrual abnormality, served as controls. The levels of both gonadotrophins (LH and FSH) and oestrogen were found to be significantly raised in all thyrotoxic patients in comparison with levels in the euthyroid female controls (P less than 0.001). "Mid cycle" LH and FSH peaks were present in thyrotoxic patients who were still menstruating whilst they were absent in those who developed amenorrhoea. Plasma oestrogen concentration rose to a peak on the day before the surge of LH (and FSH) in all euthyroid frmale controls as well as in thyrotoxic patients who were still menstruating. In contrast, oestrogen peaks occurred without ensuing LH (and FSH) peaks in thyrotoxic patients who had developed amenorrhoea, suggesting a failure of the positive feed-back mechanism. The levels and patterns of plasma progesterone in thyrotoxic subjects who were still menstruating were similar to those of euthyroid controls. However, no significant circulating plasma progesterone was detected in thyrotoxic subjects who were amenorrhoeic. The levels and patterns of all of these hormones (gonadotrophins, oestrogen and progesterone) became normal after restoration of euthyroid state and normal menstruation.

Adult↗
PubMed1974

Treatment of diabetic coma with continuous low-dose infusion of insulin.

Thirty-eight patients in diabetic coma from four different centres were treated with a continuous low-dose intravenous infusion of insulin at an average dose of 7.2 IU/hr. All patients recovered rapidly except for one profoundly shocked patient who died. The mean fall in plasma glucose was 58% four hours after the start of insulin. Blood ketone bodies and plasma free fatty acids showed a similar response. There was no significant difference in plasma glucose response according to severity of acidosis or previous treatment with insulin. Hypokalaemia was uncommon. In the treatment of diabetic coma this technique has proved simple, safe, and effective.

Adolescent↗
PubMed1974

Diabetes mellitus.

Explore the source record for details and available documents.

Alcohol Drinking↗