Study of calcium homeostasis in feline hyperthyroidism

Thirty cats with untreated hyperthyroidism were blood sampled and their calcium homeostatic mechanisms and renal function assessed. The results were compared with those obtained from 38 age-matched control cats. The hyperthyroid group of cats were found to have significantly lower blood ionised calcium and plasma creatinine concentrations and significantly higher plasma phosphate and parathyroid hormone concentrations. Hyperparathyroidism occurred in 77 per cent of hyperthyroid cats, with parathyroid hormone concentrations reaching up to 19 times the upper limit of the normal range. The aetiology, significance and reversibility of hyperparathyroidism in feline hyperthyroidism remains to be established but could have important implications for both bone strength and renal function.     

Ionized and total serum calcium and parathyroid hormone in hyperthyroidism

Total and ionized calcium concentrations as well as parathyroid hormone levels were measured in a group of hyperthyroid persons. Ionized and total calcium levels were elevated in 21 of 45 (47%) and in 12 of 45 (27%) thyrotoxic patients, respectively. Mean ionized and total calcium levels were higher in these 45 patients than in normal persons. Using two different radioimmunoassay systems for a total of 44 determinations, mean parathyroid hormone levels were lower in thyrotoxic patients than in subjects with proved hyperparathyroidism. These data suggest that [1] elevations of both ionized and total calcium concentrations occur frequently in thyrotoxic patients; [2] ionized calcium concentrations may be elevated in a higher percentage of hyperthyroid subjects than are total calcium concentrations; and [3] the hypercalcemia associated with thyrotoxicosis is not associated with elevated parathyroid hormone levels.     

Intracellular retention and rapid degradation of human calcitonin receptors overexpressed in COS cells

Overexpression of native and epitope-tagged human calcitonin (CT) receptors (hCTR-2) in COS-1 cells was performed to permit identification of the receptor protein and begin studies of receptor turnover. Data obtained with immunological techniques and cross-linking of radiolabeled salmon CT ([125I]sCT) revealed two forms of hCTR-2 in transfected cells: a larger, mature cell surface receptor (apparent size, 81 kDa) and a smaller, intracellular form (apparent size, 66 kDa). These conclusions are based on the following observations. 1) Only the larger hCTR-2 was visualized by cell surface [125I]sCT binding, whereas both species were identified by [125I]sCT binding to cell lysates. 2) Immunofluorescence studies with antibodies directed against the epitope confirmed the presence of cell surface and intracellular hCTR-2s; there were apparently many more receptors intracellularly than on the cell surface. 3) Both hCTR-2 forms were changed to a similar size of approximately 57-60 kDa by deglycosylation with endoglycosidase F; this size is consistent with that predicted by the amino acid sequence. Metabolic studies with radioactive amino acids labeled only the intracellular form. This immature form exhibited a rapid half-life of 30 min. We conclude that overexpression of native and epitope-tagged hCTR-2s in COS-1 cells leads to their intracellular retention and rapid degradation.     

Molecular determinants of calcium-dependent inactivation in cardiac L-type calcium channels

We investigated the nature and structural requirements for Ca(2+)-dependent inactivation of cardiac L-type Ca2+ channel. Investigation of subunit requirements indicates that the interaction of alpha 1 subunit with ancillary subunits, especially beta subunit, is important for this property. Replacement of the putative cytoplasmic regions of the cardiac alpha 1 subunit with skeletal muscle counterparts eliminates Ca(2+)-dependent inactivation, indicating that the site regulated by Ca2+ resides in the cytoplasmic region of the alpha 1 subunit. Deletion of the carboxy-terminal region of the cardiac alpha 1 subunit does not eliminate this property, suggesting that the modulation by protein kinase A may not be involved in this mechanism. Single amino acid substitution that strongly reduces Ca2+ selectivity of Ca2+ channels also eliminates Ca(2+)-dependent inactivation, suggesting the close link between the ion selectivity and Ca(2+)-dependent inactivation.     

Short- and long-term effects of calcitonin and calcium administration on blood calcium, magnesium and inorganic phosphorus in post menopausal osteoporosis

As a consequence of the civil war that devastated Burundi in October 1993, more than 300,000 refugees settled in the neighboring country of Rwanda. We describe the outbreak of dysentery due to Shigella dysenteriae type 1 (Sd1) that developed in Nzangwa, a camp hosting some 20,000 Burundese refugees. Between November 17, 1993 and March 10, 1994, 6,122 cases of bloody diarrhea were notified by the health information system of the camp. The overall attack rate was 32.3%, and the fatality rate was 3.8%. Children under five years of age were the most affected group of the population. All dysentery cases were treated with nalidixic acid for 5 days. The compliance assessment showed that less than 50% of the ambulatory patients completed the 5-day regimen. From 35 stool samples obtained from the refugees, seven Sd1 strains were isolated, of which three were multi-resistant to nalidixic acid. These results confirmed the morbidity and mortality of Sd1 outbreaks in the displaced populations of Central Africa. We also emphasize the difficulties in implementing effective prevention measures and appropriate case management strategies in this environment. To improve the management of patients in large Sd1 outbreaks with limited resources, we devised a clinical classification of cases according to the risk of dying.     

Activation and inactivation properties of voltage-gated calcium currents in developing cat retinal ganglion cells

The correlated activity of developing retinal ganglion cells is essential for the reorganization and refinement of retinogeniculate projections. Previous studies have uncovered marked changes in the spiking properties of retinal ganglion cells during this period of reorganization; however, a full understanding of the changes in the underlying ionic conductances has yet to be obtained. To this end, the whole-cell configuration of the patch-clamp technique was used to record currents conducted by voltage-gated calcium channels in 83 dissociated cat retinal ganglion cells obtained from animals aged between embryonic day 34 and postnatal day 105. Calcium currents, magnified by using barium as the major charge carrier, were isolated by substituting choline for Na+ in the bathing solution and Cs+ for K+ in the electrode solution. Three voltage-gated Ca2+ conductances were identified based on their voltage dependence and kinetics of activation and inactivation: a transient low-voltage-activated conductance, a transient high-voltage-activated conductance and a sustained high-voltage-activated conductance. During the developmental period examined there were significant increases in the densities of all three conductances, as well as significant changes in some of their activation and inactivation properties. These findings, together with those reported previously for the voltage-gated Na+ and K+ conductances, are related to the generation of excitability in developing retinal ganglion cells during a period critical to the normal development of the visual system. Furthermore, while the sustained high-voltage-activated conductance was present in all of the retinal ganglion cells observed, only about 72% expressed the transient high-voltage-activated current. During the developmental period examined, there was also an increase in the proportion of cells expressing the transient low-voltage-activated conductance. This, along with our previous finding that retinal ganglion cells heterogeneously express different types of voltage-gated K+ channels, strongly suggests that the spiking patterns observed in different classes of retinal ganglion cell may be due, in part, to their intrinsic membrane properties.     

Human erythrocyte bisphosphoglycerate mutase: inactivation by glycation in vivo and in vitro

2,3-Bisphosphoglycerate mutase (BPGM) [EC 5.4.2.4] is a multifunctional enzyme that catalyzes both the synthesis and the degradation of 2,3-diphosphoglycerate (2,3-DPG) and contains three types of activities in that it functions as a 2,3-DPG synthetase, a phosphoglycerate mutase and a 2,3-DPG phosphatase. In humans, BPGM occurs only in erythrocytes and plays a pivotal role in the dissociation of oxygen from hemoglobin via 2,3-DPG. The present study shows that the specific activity of BPGM in erythrocytes of diabetic patients is decreased, compared to normal controls as judged by 2,3-DPG synthetase activity and immunoreactive contents. To understand the mechanism by which the enzyme is inactivated, the enzyme was purified from pooled erythrocytes from diabetic patients and subjected to a boronate affinity column. The flow through fraction was active while the bound fraction was completely inactive. The bound fraction was reactive to an anti-hexitollysine antibody, indicating that the enzyme had undergone glycation and inactivation. The primary glycated site of the enzyme was found to be Lys158 as judged by amino acid sequencing and the reactivity with an anti-hexitollysine IgG, after reverse-phase HPLC of the lysyl-endopeptidase-digested peptides. Extensive glycation of recombinant BPGM in vitro indicated that the glycation sites were Lys2, Lys4, Lys17, Lys42, Lys158, and Lys196. From these results, the loss of enzymatic activity appears to be due to the glycation of Lys158 which may be located in the vicinity of the substrate binding site.     

Effect of vitamin E and mannitol on renal calcium oxalate retention in experimental nephrolithiasis

STUDY OBJECTIVE: To assess the efficacy of laser laparoscopic photocoagulation of endometriomas (2-18 cm) in patients with pain, infertility, or a combination of the two. DESIGN: Retrospective review of all patients with endometriomas from June 1, 1983, to December 31, 1993. SETTING: Department of gynecology and obstetrics at a district general hospital and national training center in minimal access surgery. PATIENTS: One hundred sixty-five women with large endometriomas present at the time of laser laparoscopy. INTERVENTIONS: Carbon dioxide laser or potassium-titanyl-phosphate laser laparoscopic surgery. MEASUREMENTS AND MAIN RESULTS: Ninety (74%) of 122 patients reported improvement or resolution of pain; and 30 of 66 achieved a pregnancy, for a cumulative conception rate of 45%. CONCLUSION: Laser laparoscopy is a practical, safe, and effective technique for the management of large ovarian endometriomas.     

Usefulness of calcium acetate as a chelating of phosphorus in patients in hemodialysis with secondary hyperthyroidism

In this study, we prospectively evaluated the efficacy of calcium acetate in patients with chronic renal insufficiency on hemodialysis programme with secondary hyperparathyroidism and hyperphosphatemia, which are difficult to control by means of the usual finders (calcium carbonate and aluminium hydroxide) and who were treated with pulses of calcitriol. We studied 10 patients. The inclusion criteria were: a serum phosphorus higher than 6.5 mg/dl, a serum PTHi higher than 250 pg/ml and a serum calcium higher than 9.5. The former therapy was stopped at the time of the patient was included in the study. Calcium acetate was initially introduced with doses between 2.5-4 g/day according to previous calcium and phosphate values. Also, all patients were initially treated with intermittent subcutaneous bolus of Calcitriol were modified and adjusted according to serum concentrations of calcium, phosphorus and PTHi. The concentration of calcium in the dialyzed was of 1.25 mmol/l. Fortnightly total calcium, phosphate and alkaline phosphatase serum determinations and monthly aluminium and PTHi serum determinations were carried out. During the 6 months treatment, a decrease was observed in serum concentrations of phosphate (p < 0.01), aluminum (p < 0.02) and PTHi (p < 0.001) with no changes in the values of calcium (p = ns) nor alkaline phosphatase (p = ns). The incidence of hypercalcemia was low during the follow-up period (11% of all biochemical serum determinations) and was easily controlled. We can conclude that calcium acetate is a sure and effective finder of phosphorus with a very good tolerance. Administered together with pulses of calcitriol, and the use of a low calcium concentration in the dialysate, it does not increase the risk of hypercalcemia.     

In vitro inactivation of Chlamydia trachomatis by fatty acids and monoglycerides

The antichlamydial effects of several fatty acids and monoglycerides were studied by incubating Chlamydia trachomatis bacteria with equal volumes of lipid solutions for 10 min and measuring the reduction in infectivity titer compared with that in a control solution without lipid. Caprylic acid (8:0), monocaprylin (8:0), monolaurin (12:0), myristic acid (14:0), palmitoleic acid (16:1), monopalmitolein (16:1), oleic acid (18:1), and monoolein (18:1) at concentrations of 20 mM (final concentration, 10 mM) had negligible effects on C. trachomatis. In contrast, lauric acid (12:0), capric acid (10:0), and monocaprin (10:0) caused a greater than 10,000-fold (>4-log10) reduction in the infectivity titer. When the fatty acids and monoglycerides were further compared at lower concentrations and with shorter exposure times, lauric acid was more active than capric acid and monocaprin was the most active, causing a greater than 100, 000-fold (>5-log10) inactivation of C. trachomatis at a concentration of 5 mM for 5 min. The high levels of activity of capric and lauric acids and particularly that of monocaprin are notable and suggest that these lipids have specific antichlamydial effects. The mode of action of monocaprin was further studied by removal of the lipid by centrifugation before inoculation of Chlamydia onto host cells and by electron microscopy. The results indicate that the bacteria are killed by the lipid, possibly by disrupting the membrane(s) of the elementary bodies. A 50% effective concentration of 30 microgram/ml was found by incubation of Chlamydia with monocaprin for 2 h. The rapid inactivation of large numbers of C. trachomatis organisms by monocaprin suggests that it may be useful as a microbicidal agent for the prevention of the sexual transmission of C. trachomatis.     

Mechanical strength of calcium phosphate cement in vivo and in vitro

Two different kinds of calcium phosphate cement were developed for implant fixation: cement A comprised of alpha-tricalcium phosphate (alpha-TCP) 95% and dicalcium phosphate dihydrate (DCPD) 5%, and cement B comprised of alpha-tricalcium phosphate 90% and dicalcium phosphate dihydrate 10%. The compression strength and pullout force of the new materials were tested both in vitro and in vivo. Microscopic observations were performed on the interface between bone and cement. Cement A showed a greater mechanical strength than cement B. The results suggest the clinical possibility of this calcium phosphate cement, which could be used as a material for enhancing implant fixation.     

Sotalol in hyperthyroidism

Ten hyperthyroid patients were studied before and after 2 weeks' beta-adrenoceptor blockade with sotalol. The following variables were measured: resting pulse rate, blood pressure, weight, thyroid hormone levels, plasma lipids, alkaline phosphatase, plasma glucose and insulin responses to oral glucose, bromsulphthalein retention and the 24-h urinary excretion of calcium, hydroxyproline, creatine and creatinine. Sotalol produced a significant fall in pulse and blood pressure. Weight loss continued during treatment. No metabolic changes of any consequence were found. It is concluded that sotalol should not be used as the sole treatment of a patient with hyperthyroidism.     

Hypergastrinemia in hyperthyroidism

Fasting plasma gastrin levels measured by radioimmunoassay were found to be elevated in patients with hyperthyroidism. The intravenous injection of arginine caused an increase of plasma gastrin in hyperthyroid patients as in normal subjects. The elevated gastrin level in patients with hyperthyroidism was significantly lowered after the thyroid function was normalized by treatment.     

Plasma levels of parathyroid hormone, vitamin D, calcitonin, and calcium in association with endurance exercise

Nine male marathon runners were investigated during habitual training (week 0), after 3 weeks of training break (week 3), and after 2 weeks (week 5) and 4 weeks (week 7) of retraining. Maximal oxygen uptake, body fat (BF), and plasma levels of 25(OH)D3, 1,25(OH)2D3, parathyroid hormone (PTH), calcitonin (CT), albumin, and albumin-corrected calcium were determined throughout weeks 0-7. The maximal oxygen uptake decreased after training break and increased during retraining (P = 0.002). BF did not change significantly. Plasma 1,25(OH)2D3 was elevated after training break and decreased after 2 and 4 weeks of retraining [week 0: 44.0 +/- 3.7 (SEM) pg x 1(-1); week 3: 52.4 +/- 6.0 pg x 1(-1); week 5: 42.0 +/- 2.8 pg x 1(-1); week 7: 36.9 +/- 2.3 pg x 1(-1); P = 0.03]. Plasma 25(OH)D3 did not change significantly. Plasma PTH increased throughout the training break and retraining (week 0: 1.36 +/- 0.25 pmol x 1(-1); week 3: 2.02 +/- 0.43 pmol x 1(-1); week 5: 2.23 +/- 0.60 pmol x 1(-1); week 7: 2.63 +/- 0.34 pmol x 1(-1); P = 0.03). Albumin-corrected calcium values were transiently decreased during retraining (week 3: 2.77 +/- 0.08 mM; week 5: 2.47 +/- 0.05 mM; week 7: 2.66 +/- 0.07 mM; P = 0.01). Plasma CT did not change during training break, but was transiently decreased during retraining (week 0: 9.97 +/- 0.39 pmol x 1(-1); week 3: 9.91 +/- 0.37 pmol x 1(-1); week 5: 8.19 +/- 0.50 pmol x 1(-1); week 7: 9.02 +/- 0.45 pmol x 1(-1); P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced in vitro tumor cell retention and internalization of antibody derivatized with synthetic peptides

Human IgG subclasses play a major role in the physiological regulation and functions of the immune system. There "personality" is obvious. However, the determination requires appropriate reagents and technology. For the IgG1, IgG2, IgG3 subclasses, the radial immunodiffusion technique may be sufficient. For the IgG4 subclass determination and measurement, more elaborate techniques are required. These measurements of existing proteins are of major interest in congenital as well as acquired immune deficiencies more often, besides the total subclass deficiency, these are of utmost interest to evaluate the specific response of a given subclass to a specific antigen. The IgG4 allergen specific subclass has been considered to be involved both in allergic reactions and associated with the appropriate response to allergen-specific immunotherapy. It is now accepted that IgG4 does not play an discernable role in the acute inflammatory response of type I hypersensitivity; it has also been demonstrated that a number of patients who demonstrate elevated levels of allergens specific IgG4 are not protected against allergenic exposure, and conversely, a number of patients who have been heated by immunotherapy without demonstrating any significant increase in their serum levels of allergen specific IgG4 are indeed very well protected. In the field of allergy, the IgG4 determinations remain a matter of controversy and research.     

Comparison between technetium-99m-sestamibi and hydrogen-3-daunomycin myocardial cellular retention in vitro

This study was undertaken to verify whether 99mTc-sestamibi uptake parallels that of 3H-daunomycin in cells treated with multidrug resistance (MDR) reversing agents. Since we have detected in a previous work a moderate typical MDR phenotype in rat cardiac cells, a model of cultured myocardial cells was used. METHODS: Newborn-rat cultured myocardial cells were incubated 120 min with the MDR-reversing agent verapamil 50 microM, PSC833 1 microM or S9788 10 microM alone or in combination, and the cellular retention of 3H-daunomycin and 99mTc-sestamibi was counted. RESULTS: Hydrogen-3-daunomycin cellular accumulation was never modified by more than 15% when compared to control values, while 99mTc-sestamibi decreased to 75% +/- 32% (m +/- s.d.) of controls in the presence of S9788 and to 44% +/- 19% when S9788 was associated with verapamil. CONCLUSION: The variations of 99mTc-sestamibi and 3H-daunomycin cellular accumulation induced by MDR-reversing agents in cultured myocardial cells can be dramatically different. While some MDR-reversing agents can significantly increase the 3H-daunomycin retention in cardiac cells, they have unexpected effects on that of 99mTc-sestamibi.