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J P Monson

Publications and source records attributed to J P Monson.

12 recordsLinked to original sources
PubMed1992

Effects of D-3-hydroxybutyrate and acetoacetate on lactate removal in isolated perfused livers from starved and fed rats.

We examined the influence of nutritional state on the role of the hepatic plasma membrane lactate transporter in determining overall hepatic lactate disposal. The effects of infusion of sodium D-3-hydroxybutyrate (DOHB) on lactate uptake were studied in perfused livers from fed or starved rats. In livers from starved rats, DOHB (15 to 20 mmol/L) inhibited lactate removal by approximately 45%. This effect was associated with a decrease in intracellular lactate concentration, with cell pH remaining unchanged. Inhibition was maximal when perfusate lactate was less than 1.6 mmol/L, and was undetectable at concentrations exceeding 2.5 mmol/L. A similar degree of inhibition was observed with infusion of acetoacetate. These observations add to the evidence that the inhibition of lactate removal by DOHB seen in livers from starved animals is mediated through an effect on the hepatocyte lactate transporter. At similar low levels of perfusate lactate, DOHB infusion produced a decrease in output of lactate from livers obtained from fed animals. When such livers were subjected to prolonged preperfusion, lactate removal, rather than output, was observed; in these livers DOHB stimulated lactate removal, an effect directionally opposite to that observed in livers from starved animals. These data confirm that hepatic lactate transport is a limiting factor for lactate utilization in intact livers from starved rats; in contrast, lactate utilization in livers from fed animals is limited at a step subsequent to plasma membrane transport, ie, possibly pyruvate transport into mitochondria.

3-Hydroxybutyric Acid↗
PubMed1992

Outcome of gestational diabetes in Bengali Asians living in an east London health district.

The characteristics and outcome of pregnancy complicated by gestational glucose intolerance are described in a consecutive series of 69 Bengali Asian patients and a parallel group of 22 Caucasian patients. The Bengali patients were older and of higher parity than the Caucasians and more frequently required insulin therapy. However, the outcome of pregnancy was similar in terms of antenatal clinic attendance, the number of antenatal hospital admissions, glycaemic control, birthweight and mode of delivery. Of those patients who attended for postnatal glucose tolerance test, 20% of the Bengali population demonstrated persisting abnormality of glucose tolerance, whereas no abnormalities were evident in the Caucasian group. These findings are consistent with the high prevalence and early age of onset of non-insulin-dependent diabetes in Asian populations. The World Health Organisation (WHO) criteria for the diagnosis of impaired glucose tolerance proved insufficiently sensitive for the diagnosis of gestational diabetes. This was particularly demonstrated by four patients with apparently normal glucose tolerance by WHO criteria who subsequently required insulin therapy.

Adult↗
PubMed1992

Osmoregulatory adaptation in pregnancy and its disorders.

The physiological osmoregulatory adaptations of pregnancy include decreased thresholds for both thirst and AVP secretion and increased MCR for AVP. The combined effects of these changes may unmask subclinical DI. In view of the altered relationship between serum osmolality and thirst, caution is required in investigating thirst and polyuria in pregnancy lest an erroneous diagnosis of psychogenic polydipsia be made.

Arginine Vasopressin↗
PubMed1992

Selective automatic neuropathy as a novel complication of BMT.

Neurological complications have been reported in approximately 30% of patients following bone marrow transplantation. We report a case of selective sympathetic autonomic neuropathy following allogeneic BMT, a phenomenon not previously described.

Adult↗
PubMed1991

Thyroxine replacement in post-radioiodine hypothyroidism.

Thyroxine replacement dose in 70 patients with post-radioiodine (for Graves' thyrotoxicosis) hypothyroidism was compared with that in 34 patients with autoimmune hypothyroidism matched for age and sex and diagnosed during the same period. Median replacement dose in the post-radioiodine group (100 micrograms daily) was significantly lower (P = 0.006) than in the autoimmune hypothyroid group (137.5 micrograms daily). Furthermore there was marked variation in the time elapsing from onset of post-radioiodine hypothyroidism to achievement of a given maintenance dose. These findings may be explained by persistence of non-TSH mediated thyroid function, after radioiodine therapy for Graves' thyrotoxicosis. The observations indicate the potential risk of overtreatment with thyroxine in post-radioiodine hypothyroidism unless the dose is carefully titrated against serum TSH levels. Final thyroxine requirements may not be evident in the initial phase of treatment and patients with apparently low maintenance thyroxine requirements require long-term follow up.

Adolescent↗
PubMed1990

Hormonal modulation of hepatic plasma membrane lactate transport in cultured rat hepatocytes.

Hormonal modulation of hepatic plasma membrane lactate transport was studied in primary cultures of isolated hepatocytes from fed rats to examine the mechanism for the known enhancement of lactate transport in starvation and diabetes. Total cellular lactate entry was increased by 14% in the presence of dexamethasone; this was accounted for by an approximately 40% increase in the carrier-mediated component of entry with no effect on diffusion. A trend of similar magnitude was evident with glucagon. The effects of dexamethasone and glucagon on lactate transport constitute an additional potential mechanism for enhancement of gluconeogenesis by these hormones.

Animals↗
PubMed1990

Familial acromegaly: studies in three families.

Acromegaly is usually regarded as a disease which arises sporadically except on those rare occasions in which it occurs as one component of an inherited pluriglandular syndrome. Familial acromegaly occurring in isolation has been reported only rarely. We have studied three families in each of which two first-degree relatives have developed acromegaly without clinical evidence of other endocrinopathies, in order to clarify the relationship of familial acromegaly to multiple endocrine neoplasia, type 1 (MEN 1). No further subclinical cases of acromegaly have been detected in those first-degree relatives of the index cases who were screened. In two of the families, we have found no evidence of abnormal pancreatic or parathyroid function either in the acromegalic index cases or their asymptomatic relatives: a diagnosis of MEN 1 is therefore effectively excluded. In the third family, the presence of multiple subcutaneous lipomata in several members of the family and elevation of PTH levels in two (normocalcaemic) acromegalic index cases, might indicate a highly atypical presentation of MEN 1. None of the six acromegalic index cases had elevations of circulating growth hormone releasing hormone levels. We conclude that isolated familial acromegaly may be more common than has hitherto been realized and that, in these families at least, ectopic production of growth hormone releasing hormone is not responsible.

Acromegaly↗
PubMed1990

Impact of conventional and three-dimensional thallium-technetium scans on surgery for primary hyperparathyroidism.

Twenty-nine patients with primary hyperparathyroidism underwent double-tracer subtraction scanning after injection of 201Tl as thallous chloride for thyroid and parathyroid images followed by 99mtechnetium as sodium pertechnetate for thyroid images prior to surgical exploration of the neck. The operative findings were correlated with the scans. All 23 adenomas (100%) and 13 of 18 (72%) hyperplastic glands were correctly localized. The ability of the scan to identify abnormal parathyroids was determined by the gland mass rather than whether the tissue was adenomatous or hyperplastic as all 32 (100%) abnormal glands weighing more than 180 mg were successfully localized in contrast to four of nine (44%) glands weighing less than 180 mg. An additional technique, in which emission tomography was carried out after subtraction scintigraphy, was used on 11 patients in the series. In all 11, the site of a single abnormal gland was predicted by the conventional subtraction scan: in nine of these patients, emission tomography provided additional localization of the gland in the anteroposterior plane.

Humans↗