Biomedical subjects

R Arem

Publications and source records attributed to R Arem.

31 records · Page 2Linked to original sources

PubMed1986

Selective osmoreceptor dysfunction presenting as intermittent hypernatremia following surgery for a pituitary chromophobe adenoma.

Intermittent hypernatremia following hypothalamic surgery or trauma is usually attributed to the triphasic dysfunction of vasopressin release (diabetes insipidus, inappropriate vasopressin release, and diabetes insipidus). A 39-year-old patient had hypodipsia and intermittent hypernatremia following hypothalamic surgery for a chromophobe adenoma. Mean arterial pressure fell by 25 percent during orthostasis testing and was associated with an increase in vasopressin levels from 1.3 microU/ml to 12 microU/ml. Plasma renin activity and aldosterone increased from 1.1 to 16 ng/ml per hour and from 6.7 to 39 ng/dl, respectively, and remained elevated for three and a half hours after tilt testing. Hypertonic saline infusion, on the other hand, increased serum osmolality from 290 to 304 mOsm/kg but did not result in a significant rise in vasopressin levels (all were less than 1 microU/ml). These results are consistent with a selective dysfunction of the osmoreceptor pathways of vasopressin release and intact volume receptor-mediated pathways. Patients with intermittent hypernatremia following hypothalamic surgery or trauma should be questioned specifically regarding thirst. If it is impaired or absent, these patients should be watched carefully, not only for the development of triphasic dysfunction of vasopressin release, but also for a selective osmoreceptor dysfunction associated with thirst deficits as found in patients with "essential hypernatremia."

Adult↗

PubMed1986

Concomitant Graves' disease and primary hyperparathyroidism. Influence of hyperthyroidism on serum calcium and parathyroid hormone.

Two patients with coexistent Graves' disease and primary hyperparathyroidism were studied during medical treatment of their hyperthyroidism. Serum free calcium level was initially quite elevated (1.61 and 1.71 mM, normal 1.12 to 1.28 mM), but immunoreactive parathyroid hormone values were only slightly increased. The immunoreactive parathyroid hormone values of 153 and 173 nleq/ml (normal less than 150 nleq/ml) were far lower than expected in hyperparathyroid patients with a similar degree of hypercalcemia. As the patients became euthyroid during thionamide treatment, calcium values decreased to 1.39 and 1.61 mM, respectively, and parathyroid hormone increased to values clearly suggestive of hyperparathyroidism (454 and 229 nleq/ml, respectively). Parathyroidectomy and subtotal thyroidectomy cured both the hyperparathyroidism and the thyrotoxicosis in each case. These observations suggest that thyroid hormone had potentiated the osteoclastic effects of parathyroid hormone and that the resulting exacerbation of hypercalcemia had produced a relative suppression of hormone secretion by the abnormal parathyroid tissue.

Aged↗

PubMed1986

Restriction fragment length polymorphism of the human insulin gene region among type II diabetic Mexican-Americans and Tunisians.

The human insulin gene is flanked by a polymorphic locus that is located approximately 500 base pairs (bp) from the 5' end of the point where transcription begins (Bell et al. 1981; Bell et al, 1982). Its occurrence is due to an insertion-deletion region which gives rise to two major classes of alleles: those containing small insertions of 0-600 bp and those containing larger insertions of 1,600-2,200 bp (Owerbach and Nerup, 1982). Insertions of 600-1,600 bp are rare (Rotwein et al., 1983). The larger insertions have previously been reported to be associated with type 2 diabetes (Owerbach and Nerup, 1982). We have conducted studies on a Mexican-American population in Starr County, Texas (98% Mexican-American) and a Tunisian population in Tunis, Tunisia, to determine if the frequency distribution of these classes of insulin gene alleles are similar to the previously reported frequency distributions and if any of the classes of alleles are associated with type 2 diabetes in these populations. We conclude that none of the classes of insulin gene alleles are associated with type II diabetes among Mexican-Americans or Tunisians, and that the frequency distributions of the insulin gene alleles do not vary significantly between the Tunisians, Mexican-Americans, or the aggregate data resulting from combining the insulin gene frequencies of several of the populations described thus far (Bell et al., 1984).

Adult↗

PubMed1985

The role of calcium in the induction of refractoriness to cyclic AMP stimulation by TSH.

An initial exposure of beef thyroid slices to 25 mU/mL thyroid-stimulating hormone (TSH) for two hours induces a diminished stimulation of cyclic adenosine monophosphate (AMP) production upon subsequent readdition of TSH but does not modify the effect of prostaglandin E1 (PGE1). Incubation of thyroid slices in calcium-free buffer with or without 2 mmol/L ethylene glycol bis (beta-aminoethyl ether)--N,N' = tetracetic acid (EGTA) prevented desensitization induced by TSH and PGE1, to the subsequent stimulation by TSH and PGE1, respectively, despite the presence of calcium in subsequent incubations. TSH-induced desensitization was not modified by increasing the calcium concentration up to 50 mmol/L in the initial incubation. However, the stimulatory effect of TSH upon cyclic AMP levels was decreased as the calcium concentration in the first incubation was increased. In the presence of at least 1 mmol/L calcium, an initial incubation of thyroid slices with 20 mumol/L ionophore A-23187 decreased the stimulation of cyclic AMP by 25 mU/mL TSH added to the slices for the first time during a subsequent incubation. Under these conditions, A-23187 had no effect on PGE1 stimulation of cyclic AMP. These results indicate that calcium may play a role in the TSH-induced, but not PGE1, desensitization of cyclic AMP formation.

Alprostadil↗

PubMed1985

Insulin overdose in eight patients: insulin pharmacokinetics and review of the literature.

Eight patients are reported who attempted suicide by self-administering insulin. Review of the literature reveals that most patients who attempt suicide in this manner are insulin-requiring diabetics, and depression or another psychiatric illness is recognized in the majority. The amount of insulin used varied from 20 units to 3200 units. The duration of the hypoglycemic effect that may be as long as several days, seems to correlate with the dose and type of insulin administered, and may be determined predominantly by the slow release of insulin from the injection site. Recurrence of insulin overdose has been frequently documented. The adult respiratory distress syndrome, not previously described in patients with insulin overdose, occurred in two of our cases, and various mechanisms for this complication are considered. Serious neurologic sequelae and death may be related to delay in therapy, and glucose requirements appear to be higher during the first 24 hours of therapy. Insulin overdose with suicidal intent may be more common than generally thought and should be considered in diabetic patients with severe unexplained hypoglycemia.

Adult↗

PubMed1984

Role of calcium in acetylcholine-induced desensitization in dog thyroid slices.

Incubation of dog thyroid slices with 1 microM acetylcholine (ACH) for 3 h followed by a second 2-h incubation without it induces a diminution of stimulation of glucose oxidation by ACH during a third incubation of 45 min. Using a calcium-free medium during all incubations prevents the desensitization and reduces, but does not abolish, ACH stimulation of glucose oxidation. EGTA [ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid] (2 mM) added to the calcium-free medium in all incubations prevents both refractoriness and stimulation of glucose oxidation induced by ACH. Calcium depletion during the first incubation only, achieved by using EGTA and a calcium-free medium, also prevents refractoriness but not the augmentation of glucose oxidation caused by ACH. Incubation of thyroid slices with 1 microM ionophore A23817 during the 3-h first incubation decreases the stimulation of glucose oxidation induced by its readdition or by 1 microM ACH added for the first time in the third incubation. Ionophore-induced desensitization is not related to a cholinergic muscarinic receptor effect. Initial incubation of dog thyroid slices with 1 microM ACH diminishes the subsequent stimulation of glucose oxidation by 0.5 microM ionophore. However, the ACH-induced desensitization to ionophore can be overcome by a 10-fold increase in the amount of ionophore in the third incubation. Ionophore (1 microM) in the first incubation also induces refractoriness to thyroid-stimulating hormone (TSH) (10 mU/ml)-stimulated glucose oxidation in the third incubation. In contrast, initial incubation of thyroid slices with TSH (25 mU/ml) does not affect the stimulation of glucose oxidation by 0.5 microM ionophore added during the third incubation. These results suggest that increased intracellular calcium plays a major role in, or even mediates, ACH-induced desensitization in the thyroid gland.

Acetylcholine↗

PubMed1984

Gastrointestinal tract complications of diabetes mellitus. Pathophysiology and management.

Diabetes mellitus can affect every organ system, including large and small blood vessels, eyes, nerves, kidneys, and the gastrointestinal (GI) tract. We reviewed recent knowledge concerning the impact of diabetes on the gut. While the incidence of GI tract complications is usually considered relatively low, functional alterations have been demonstrated at every level in the gut and account for considerable morbidity in the diabetic population.

Anal Canal↗

PubMed1983

Exposure of dog thyroid slices to acetylcholine induces refractoriness to its subsequent stimulation of glucose oxidation.

An initial incubation of dog thyroid slices with 0.1 or 1 microM acetylcholine (ACH) for at least 2 h decreases its subsequent stimulation of [1-14C]glucose oxidation. Refractoriness persists for as long as 6 h in the absence of ACH. While new protein synthesis is essential for recovery, it is not necessary for its induction. Refractoriness is prevented when 25 microM tropicamide, an atropine-like drug, is present from the beginning of the initial incubation, but not when it is added after 2 h of incubation of slices with ACH, indicating that at this time ACH is no longer necessary for refractoriness. During refractoriness induced by ACH, stimulation of glucose oxidation by thyroid-stimulating hormone, prostaglandin E1, dibutyryl cyclic AMP, and cholera toxin, but not menadiol, is also significantly diminished. Incubation of thyroid slices with ACH does not modify its stimulation of iodide organification or 32Pi incorporation into phospholipids. These results suggest that the desensitization is not due to changes in the ACH receptor but rather to intracellular metabolic effects. This phenomenon may be important in the regulation of cholinergic effects on the thyroid.

Acetylcholine↗

PubMed1983

Amenorrhea-galactorrhea and craniopharyngioma.

A 40-year-old woman had a 1-year history of amenorrhea-galactorrhea. She was found to have an intrasellar tumor with suprasellar extension and a prolactin level of 98.1 ng/mL. Subtotal resection of the tumor resulted in a return of the prolactin level to normal within 4 days of the operation and of the prolactin response to thyrotropin releasing hormone, accompanied by the disappearance of the galactorrhea. Histologic examination revealed a typical craniopharyngioma. These observations indicate that one important mechanism of hyperprolactinemia in patients with craniopharyngioma is direct encroachment on the hypothalamus and/or pituitary stalk by the tumor and interruption of prolactin inhibiting factor.

Adult↗

PubMed1983

Sulfonamide-induced hypoglycemia in chronic renal failure.

Severe hypoglycemia with an inappropriately elevated insulin level occurred in a patient with chronic renal failure who was taking two tablets of sulfamethoxazole and trimethoprim twice a day for a urinary tract infection. Hypoglycemia was readily corrected with intravenous glucose and did not recur after discontinuation of the sulfonamide. Insulin and glucose determinations during a 48-hour fast while the patient was rechallenged with this compound, as compared with those obtained during a 72-hour fast performed 12 days after discontinuation of the therapy, suggest that the hypoglycemic episode was related to hyperinsulinemia probably induced by the sulfonamide. Other factors, including congestive heart failure, growth hormone deficiency, and hypoalaninemia might have contributed to the development of hypoglycemia in this patient.

Aged↗

PubMed1982

Polycythemia rubra vera and artifactual hypoglycemia.

A patient with polycythemia rubra vera had had a leukocyte count between 55,000 and 86,000/cu mm and had had serum glucose levels as low as 8 mg/dL. Despite these low serum glucose values, the patient was asymptomatic, and a more careful investigation disclosed that the hypoglycemia was artifactual. This phenomenon, reported in other leukemic states, to our knowledge, has not been previously described in patients with polycythemia rubra vera. Our case broadens the spectrum of the causes of artifactual low serum glucose concentration due to excessive glucose consumption by the WBCs. This phenomenon is related to extreme leukocytosis, regardless of the underlying disease. Unnecessary workup for hypoglycemia can be avoided if its artifactual nature is suspected in any patient with a reported low serum glucose level and high WBC count.

Aged↗

PubMedDate not supplied

Thyroid microcarcinoma: prevalence, prognosis, and management.

OBJECTIVE: To review the usual course of thyroid microcarcinoma (TMC) and the associated prognosis and treatment of affected patients. METHODS: We discuss predisposing factors in the formation of TMC and the modulation of its behavior, diagnostic evaluation, and management options. RESULTS: TMC, generally defined as a well-differentiated thyroid cancer less than or equal to 15 mm in diameter, has an estimated prevalence (based on autopsy studies) of about 5 to 10%. Studies, however, have shown that most of these cancers are smaller than 5 mm in diameter. The high prevalence of TMC in the general population contrasts with the rarity of thyroid cancers of greater size, which constitute less than 1% of malignant neoplasms in the United States. The frequent detection of TMC as a result of routine imaging of the neck for unrelated reasons and as a incidental finding in surgical specimens has raised a question about whether the management of TMC should differ from that for thyroid cancer of appreciable size. The uncertainty about optimal management of TMC is attributable to the small number of long-term follow-up studies as well as the common observation that patients usually have an excellent prognosis. Although in most patients harboring a TMC the cancer remains quiescent and never becomes clinically significant, in some cases TMC can demonstrate an aggressive course. Several variables, such as older age, multifocality, bilateral disease, and extrathyroidal spread at initial assessment, may have some adverse prognostic significance. After a partial surgical removal of the thyroid gland for TMC, the recurrence rate may be as high as 11%. Therefore, a treatment dilemma is caused by the low propensity of TMC for progression to clinically significant disease, yet the potential for recurrence and aggressive behavior in some cases. CONCLUSION: In general, surgical resection of TMC is based on results of fine-needle aspiration biopsy and the rate of growth of the nodule. Aggressive management seems indicated in high-risk patients, particularly older patients, those with a history of radiation exposure, and those with multifocal disease, bilateral disease, or lymph node involvement.

Journal Article↗

PubMedDate not supplied

Ipodate therapy in patients with severe destruction-induced thyrotoxicosis.

We describe 4 patients with severe destruction-induced thyrotoxicosis who had a rapid clinical response to oral sodium ipodate (500 mg daily). The underlying thyroid disorders in the patients were postpartum thyroiditis, subacute thyroiditis, silent thyroiditis, and radiation-induced thyroiditis. Ipodate therapy was given for 6 to 10 weeks until restoration of thyroid function to normal. In all patients, an almost complete resolution of symptoms occurred by the third day of ipodate treatment. In the patient with radiation thyroiditis, a daily clinical score of thyrotoxicosis declined within 2 to 3 days. The score remained low as long as the patient was receiving ipodate, but 2 attempts to discontinue ipodate therapy while thyroxine levels were elevated resulted in a rise of the thyrotoxicosis clinical score. This suggests that ipodate therapy, by rapidly reducing triiodothyronine levels through inhibition of the 5' monodeiodination and blockage of the peripheral effects of thyroid hormone, controls severe thyrotoxicosis mediated by destruction and should be considered in this setting in conjunction with beta-adrenergic blockade.

Adolescent↗