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Biomedical subjects

Rafael Luboshitzky

Publications and source records attributed to Rafael Luboshitzky.

At least 19 recordsLinked to original sources
PubMed2005

Evaluation of the pituitary-adrenal axis function following single intraarticular injection of methylprednisolone.

OBJECTIVE: To determine the effects of a single session of intraarticular methylprednisolone (IA-MP) injections on the function of the pituitary-adrenal axis. METHODS: Twenty-five patients with rheumatic diseases were treated with a single IA-MP injection. The dose varied between 20 and 160 mg. The basal cortisol level and the response to 1 microg adrenocorticotropic hormone (ACTH) stimulation were determined before treatment, at 1 day, and at 1 week after IA-MP injections. Further tests were carried out for up to 6 weeks in patients with blunted cortisol response. Results were compared with those obtained in a group of 22 healthy subjects. RESULTS: Before treatment, all patients had normal basal and peak cortisol responses to ACTH (>396 nmoles/liter at 30 minutes). Reduced fasting cortisol levels (<147 nmoles/liter) were detected in 12 of 25 patients (48%) after 1 day, in 1 of 25 patients (4%) after 1 week, and in 1 of 25 patients (4%) 2 weeks after IA-MP injections. Blunted peak cortisol response (<396 nmoles/liter at 30 minutes) was observed in 1 of 25 patients (4%) after 1 day, in 3 of 25 patients (12%) after 1 week, and in 1 of 25 patients (4%) 2 weeks after IA-MP injections. Decreased fasting levels and peak cortisol responses to ACTH stimulation were more common in patients with inflammatory diseases and in those injected with 80-160 mg MP. CONCLUSION: Single-session IA-MP injection(s) are associated with systemic absorption of MP, causing impaired adrenocortical reserve. Recovery is expected in most patients after 1-2 weeks. Only a few patients exhibited suppression for up to 2 weeks. The magnitude of this suppression depends on the dose injected, and is more common in patients with inflammatory joint diseases. Caution is required if repeated large doses of IA-MP are considered in these patients.

Adrenocorticotropic Hormone↗
PubMed2005

Altered luteinizing hormone and testosterone secretion in middle-aged obese men with obstructive sleep apnea.

OBJECTIVE: To elucidate the causes for the decline in testosterone levels observed in men with obstructive sleep apnea (OSA). RESEARCH METHODS AND PROCEDURES: We determined serum luteinizing hormone (LH) and testosterone levels every 20 minutes between 7 pm and 7 am with simultaneous sleep recordings in five obese middle-aged men with OSA, in five age- and BMI-matched controls, and in six lean young healthy men. RESULTS: The mean and area under the curve (AUC) values of LH and testosterone were significantly lower in men with OSA compared with controls. Young controls had significantly more testosterone pulses of shorter interpulse duration than OSA subjects and middle-aged controls. After adjusting for age and BMI, the three groups differed in mean and AUC values of LH and testosterone. Analysis of covariance, using BMI as a covariate, revealed a statistically significant group effect on mean and AUC testosterone values (p = 0.03; p < 0.003, respectively). Eliminating young controls, there was a significant positive correlation between the amount of LH and testosterone secreted at night. After partialling out age alone and BMI alone, the mean LH and mean testosterone were still positively correlated. DISCUSSION: Thus, OSA is associated with decreased pituitary-gonadal function. The decline in testosterone concentrations is due to obesity and advanced age and to a lesser degree to sleep fragmentation and hypoxia.

Body Mass Index↗
PubMed2004

Combined adrenal myelolipoma and medullary hyperplasia.

OBJECTIVE: A patient is reported with hypertension due to combined medullary adrenal hyperplasia and myelolipoma. METHODS: A 52-year-old woman with long-standing hypertension was evaluated for an incidentally discovered large tumor of the left adrenal. Left adrenalectomy was performed for a presumptive clinical diagnosis of pheochromocytoma. RESULTS: Histopathologic examination revealed a mixed tumor consisting of a large myelolipoma with infiltrating foci of adrenal medulla. CONCLUSIONS: A patient is described with hypertension, myelolipoma and adrenal medullary hyperplasia; following adrenalectomy, however, blood pressure and biochemical abnormalities normalized.

Adrenal Gland Neoplasms↗
PubMed2004

Mixed follicular-medullary thyroid carcinoma: a case report.

We report on a 35-yr-old woman presenting with a single thyroid nodule. Fine-needle aspiration (FNA) of the nodule was reported to contain both follicular and parafollicular cells. The biphasic nature of the tumor was highlighted on immunohistochemical investigation of the cellblock. Positive staining for thyroglobulin was limited to the follicular structures and the dense areas stained positive for calcitonin. The serum calcitonin level was highly elevated. Surgery was recommended because of suspected malignancy. The patient underwent total thyroidectomy. The diagnosis of mixed medullary and follicular carcinoma of the thyroid was established by histological investigation using immunohistochemical staining for thyroglobulin, chromogranin, and calcitonin. The patient was well 1 yr after the operation. Repeated measurements of serum calcitonin levels were normal. Total body scan revealed no radioactive iodine uptake in the thyroid bed, bones, or lungs.

Adenocarcinoma, Follicular↗
PubMed2004

Cardiovascular risk factors in middle-aged women with subclinical hypothyroidism.

OBJECTIVES: Overt hypothyroidism (OH) is associated with premature atherosclerosis and coronary heart disease (CHD). Recently, C-reactive protein (CRP) and total homocysteine (tHct) emerged as additional independent cardiovascular risk factors. Subclinical hypothyroidism (SH), affecting as many as 15% of middle-aged women is not known to be associated with risk for CHD. DESIGN AND MEASUREMENTS: We measured CRP and tHct levels as well as conventional cardiovascular risk markers in 44 middle-aged women with newly diagnose SH. Results were compared with those obtained in 10 patients with OH and 19 euthyroid controls. RESULTS: In SH, tHct and CRP levels were not as augmented as compared to controls. Their mean systolic and diastolic blood pressure values were increased vs. controls (p<0.04;p<0.01, respectively). Mean values of total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglycerides, TC/HDL-C and LDL-C/HDL-C were not different in patients with SH compared to controls. Individual analysis revealed that the percentage of patients with SH having hypertension, hypertriglyceridemia, hypercholesterolemia, elevated TC/HDL-C and LDL-C/HDL-C ratios were higher than the percentage in controls. CRP positively correlated with BMI(r=0.29,p<0.02), and tHct positively correlated with age (r=0.24, p<0.05). CONCLUSIONS: Our findings suggest that subclinical hypothyroidism in middle-aged women is associated with hypertension and dyslipidemia. CRP and tHct do not appear to contribute to the increased risk for CHD in these patients.

Adult↗
PubMed2003

Middle-aged men secrete less testosterone at night than young healthy men.

Aging men largely maintain their testicular androgen production. Cross-sectional studies have demonstrated that after the age of 40 yr a 0.2-2% annual decline is observed in morning total testosterone. In elderly males, the coordinate release of LH and testosterone became asynchronous despite normal serum levels of these hormones. The aim of this study was to test the reproductive hormone rhythm at night in middle-aged men. We studied seven healthy middle-aged (46.6 +/- 6.7 yr) and six healthy young (23.9 +/- 2.4 yr) men by determining their serum levels of LH and testosterone levels every 15 min from 1900-0700 h with simultaneous sleep recordings. The nocturnal rise in testosterone occurred earlier in young men (2235 +/- 0022 h) and at 2331 +/- 0057 h in middle-aged men (P < 0.04). In young men, the mean testosterone level at night (5.0 +/- 1.3 ng/ml; 17.4 +/- 4.4 nmol/liter) and the integrated nocturnal secretion [area under the curve (AUC); 60.6 +/- 8.9 ng/ml.h; 210 +/- 31 nmol/liter.h] were significantly higher compared with the values (3.6 +/- 1.1 and 31.1 +/- 7.2 ng/ml.h; 12.6 +/- 3.8 and 108 +/- 24.8 nmol/liter.h, respectively) observed in middle-aged men (P < 0.04 and P < 0.01, respectively). The mean (3.5 +/- 0.3 mIU/ml; 3.5 +/- 0.3 IU/liter) and AUC (43.4 +/- 8.3 mIU/ml.h; 43.4 +/- 8.3 IU/liter.h) LH values in middle-aged men were significantly higher than the values observed in young men (2.0 +/- 0.7 and 30.8 +/- 6.1 mIU/ml.h; 2.0 +/- 0.7 and 30.8 +/- 6.1 IU/liter.h; P < 0.05 and P < 0.01, respectively). Young men had significantly more testosterone pulses at night (6.7 +/- 1.6/12 vs. 3.8 +/- 1.1/12 h in middle-aged men; P < 0.005) of shorter interpulse interval (88.5 +/- 23.6 vs. 137.4 +/- 46.4 min; P < 0.02). LH pulse characteristics and sleep quality were similar in both groups. However, the first rapid eye movement (REM) sleep episode occurred earlier in middle-aged men (2303 +/- 0034 h) vs. young men (0010 +/- 0054 h; P < 0.04). As a consequence, the testosterone rise antedated the first REM episode by 90 min in young men. The link between testosterone rise and REM sleep episode was not observed in middle-aged men. Linear regression analysis revealed that the LH AUC was significantly related to age (P < 0.02). Analysis of covariance revealed that the two groups differed significantly in testosterone AUC (P < 0.04). Comparison of LH and testosterone concentrations showed significant and positive cross-correlations between LH and testosterone only in young men, with the testosterone rise lagging 60 min after the rise in LH. Our findings suggest that in middle-aged men, less pulsatile testosterone and more LH are secreted at night than in young men, with disruption of the association between testosterone rhythm and REM sleep. The decline in nocturnal testosterone secretion appears to involve a combination of testicular and pituitary hypogonadism.

Adult↗
PubMed2003

Plasma levels of nitric oxide and L-arginine in sleep apnea patients: effects of nCPAP treatment.

Sleep apnea syndrome has been shown to be associated with decreased levels of circulating nitric oxide (NO) after waking up from sleep. In this study we investigated overnight plasma concentrations of NO in sleep apnea patients before and after nasal continuous positive airway pressure (nCPAP) treatment and the effects of nCPAP on morning levels of L-arginine. In experiment 1, NO concentrations measured hourly during sleep were found to be significantly lower in a group of eight sleep apnea patients in comparison with six age-similar snorers and six normal young adults. In experiment 2, overnight NO concentrations were compared in 5 sleep apnea patients before and 9.3 +/- 3.9 mo after treatment with nCPAP. A significant increase in NO concentrations was found in four out of five patients, and a significant increase in L-arginine was found in all five patients after treatment. In experiment 3, removal of nCPAP for a single night in seven sleep apnea patients caused a significant decrease in morning levels of NO and L-arginine. These results demonstrate that sleep apnea is associated with a chronic state of diminished circulating NO concentrations that can be ameliorated by nCPAP treatment.

Adult↗
PubMed2003

Pituitary-gonadal function in men with obstructive sleep apnea. The effect of continuous positive airways pressure treatment.

OBJECTIVES: Decreased libido and a decline in morning serum testosterone levels were reported in men with obstructive sleep apnea (OSA). Our study aimed to evaluate the pituitary-gonadal axis in middle age men with OSA before and after treatment with nasal continuous positive airway pressure (CPAP). MATERIAL AND METHODS: Measurement of the nocturnal serum luteinizing hormone (LH) and testosterone levels and sleep recordings before and after nine months of CPAP treatment in five men with OSA aged 49.5+/-5.2 years. Patients were evaluated during nocturnal sleep at base line and during CPAP treatment. Serum LH and testosterone levels were determined at 20 minutes interval between 1900h and 0700h with concomitant determination of sleep quality, respiration and oxygen saturation. RESULTS: At base line, patients had higher RDI and PaO2<90%, lower mean and integrated (AUC) values of LH and testosterone. During CPAP treatment, RDI and PaO2<90% were normal. Mean and AUC values of testosterone and LH increased. CONCLUSIONS: OSA in men is associated with dysfunction of the pituitary-gonadal axis. The central suppression of nocturnal testosterone in these patients is partially corrected during chronic CPAP treatment.

Adult↗
PubMed2002

Risk factors for cardiovascular disease in women with subclinical hypothyroidism.

Overt hypothyroidism may result in accelerated atherosclerosis and coronary heart disease (CHD) presumably because of the associated hypertension, hypercholesterolemia, and hyperhomocysteinemia. As many as 10%-15% of older women have subclinical hypothyroidism (SH) and thyroid autoimmunity. Whether SH is associated with risk for CHD is controversial. We examined 57 women with SH and 34 healthy controls. SH was defined as an elevated thyrotropin (TSH) (>4.5 mU/L) and normal free thyroxine (FT(4)) level (8.7-22.6 nmol/L). None of the patients had been previously treated with thyroxine. In all participants we determined blood pressure, body mass index (BMI), and fasting TSH, FT(4), antibodies to thyroid peroxidase and thyroglobulin, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, folic acid, vitamin B(12), creatinine, and total plasma homocysteine levels. The SH and control groups did not differ in their total homocysteine values. Mean diastolic blood pressure was increased in SH patients versus controls (82 vs. 75 mm Hg; p < 0.01). Mean values of TC, HDL-C, LDL-C, triglycerides, TC/HDL-C, and LDL-C/HDL-C were not different in patients with SH compared with controls. Individual analysis revealed that the percentage of patients with SH having hypertension (20%), hypertriglyceridemia (26.9%), elevated TC/HDL-C (11.5%), and LDL-C/HDL-C (4%) ratios were higher than the percentages in controls. Hyperhomocysteinemia (> or = 10.98 micromol/L) was observed in 29.4% of SH and was not significantly different from the percentage in controls (21.4%). No significant correlation between TSH and biochemical parameters was detected. We conclude that subclinical hypothyroidism in middle-aged women is associated with hypertension, hypertriglyceridemia, and elevated TC/HDL-C ratio. This may increase the risk of accelerated atherosclerosis and premature coronary artery disease in some patients.

Adult↗
PubMed2002

Decreased pituitary-gonadal secretion in men with obstructive sleep apnea.

Decreased libido is frequently reported in male patients with obstructive sleep apnea (OSA). The decline in morning serum testosterone levels previously reported in these patients was within the normal adult male range and does not explain the frequent association of OSA and sexual dysfunction. We determined serum LH and testosterone levels every 20 min between 2200-0700 h with simultaneous sleep recordings in 10 men with sleep apnea and in 5 normal men free of any breathing disorder in sleep. The mean levels and area under the curve of LH and testosterone were significantly lower in OSA patients compared with controls [LH, 24.9 +/- 10.2 IU/liter.h vs. 43.4 +/- 9.5 (P < 0.005); testosterone, 67.2 +/- 11.5 nmol/liter.h vs. 113.3 +/- 26.8 (P < 0.003)]. Four of 10 patients had hypogonadal morning (0700 h) serum testosterone levels. Analysis of covariance (ANCOVA) revealed that the 2 groups differed significantly in the amount of LH and testosterone secreted at night independent of age or degree of obesity. After partialing out body mass index, there was a significant negative correlation between the amounts of LH and testosterone secreted at night and the respiratory distress index, but not with degree of hypoxia. Our findings suggest that OSA in men is associated with dysfunction of the pituitary-gonadal axis. The relation between LH-testosterone profiles and the severity of OSA suggests that sleep fragmentation and, to a lesser extent, hypoxia in addition to the degree of obesity and aging may be responsible for the central suppression of testosterone in these patients.

Adult↗
PubMed2002

The effect of pyridoxine administration on melatonin secretion in normal men.

OBJECTIVES: To determine pineal response to pyridoxine in normal men. MATERIAL AND METHODS: Twelve healthy men were given orally pyridoxine (100 mg) or placebo at 1700h. Serum melatonin levels were determined every 30 minutes with simultaneous measurement of core body temperature between 1700h to 0300h. Polysomnographic sleep recordings were performed between 1800h to 2000h. RESULTS: Serum melatonin levels after both placebo and pyridoxine showed a nocturnal rise occurring at 22:10+/-1:22h and 22:24+/-1:09h, respectively. The melatonin onset, peak, mean and area under the curve (AUC) values after pyridoxine (3.2+/-1.6 pg/ml, 47.2+/-22.6 pg/ml, 31.5+/-11.0 pg/ml and 173.5+/-138.4 pg/ml x min, respectively) were similar to the values after placebo administration (4.7+/-1.6 pg/ml, 53.9+/-26.0 pg/ml, 37.2+/-2.8 pg/ml and 205.3+/-137.8 pg/ml x min, respectively). CBT revealed a significant nocturnal decline but without significant difference between pyridoxine and placebo. Sleep amount and architecture were similar after the two treatments. CONCLUSIONS: In adult man, the oral administration of 100 mg-pyridoxine during the evening hours has no effect on melatonin secretion nor does it alter CBT or sleep quality.

Adult↗
PubMed2002

Cyproterone acetate-ethinyl estradiol treatment alters urinary 6-sulfatoxymelatonin excretion in hyperandrogenic women.

OBJECTIVES: To investigate melatonin production in hyperandrogenic women before and during treatment with cyproterone acetate and ethinyl estradiol (Diane 35). MATERIAL AND METHODS: We studied 10 women with late onset adrenal hyperplasia due to 21-hydroxylase deficiency (LOCAH) and 10 women with idiopathic hirsutism (IH). Patients were treated with Diane 35 for four months. Fasting blood samples for the determination of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone and dihydroepiandrosterone sulfate (DHEAS) and 24-hour urine collections for the determination of 6-sulfatoxymelatonin (aMT6s) excretion were obtained from all patients at baseline and after 4 months of treatment. Results were compared with those obtained in 15 control women. RESULTS: At baseline, women with LOCAH had significantly higher serum testosterone, 17-hydroxyprogesterone (17OHP) and ACTH stimulated 17OHP values than IH and control women. Their aMT6s values (51.0+/-20.5 mg/24h) were significantly higher than the values in IH (34.3+/-7.1) and control women (30.5+/-6.5) (p< 0.001). Diane 35 treatment significantly decreased serum LH, FSH and testosterone levels and aMT6s values in LOCAH patients (29.8+/-16.6 mg/24h) (p<0.0001) in LOCAH patients. CONCLUSIONS: These results indicate that hyperandrogenic women with LOCAH have increased melatonin production. The normalization of aMT6s and testosterone values during cyproterone acetate-ethinyl estradiol treatment, suggest that sex steroids either directly or through the suppression of gonadotropin, modulate melatonin secretion in these patients.

Adolescent↗
PubMedDate not supplied

Serum thyroglobulin levels after fine-needle aspiration of thyroid nodules.

OBJECTIVE: To investigate whether a minor insult to the thyroid gland attributable to fine-needle aspiration (FNA) or external thyroid palpation can cause a release of serum thyroglobulin (Tg) into the circulation. METHODS: We determined serum Tg levels before and at 60 minutes and 15 days after FNA in 25 patients with thyroid nodules. Results were compared with those obtained in 25 patients with thyroid nodules, in whom serum Tg concentrations were determined before and 60 minutes after palpation of the thyroid, and in 15 healthy subjects without thyroid disease, who had no thyroid palpation and no FNA, from whom 2 blood specimens were obtained 60 minutes apart. All participants had normal results of thyroid function tests and no detectable antithyroglobulin or thyroid peroxidase antibodies. RESULTS: After FNA, 22 of 25 patients had significant elevation of serum Tg concentrations. The Tg levels returned to baseline values 15 days after FNA. In 4 of the 25 patients with thyroid nodules who had palpation of the thyroid, a significant increase in serum Tg levels was elicited. None of the 15 healthy subjects with normal thyroid glands (and with no FNA or thyroid palpation) had significant Tg elevations. CONCLUSION: FNA causes a significant increase in serum Tg concentrations, which may persist for 15 days. Therefore, Tg assay should not be scheduled prematurely after FNA.

Adult↗
PubMedDate not supplied

Melatonin administration alters semen quality in healthy men.

The role of melatonin in the regulation of reproduction in humans is unknown. We conducted a 6-month, double-blind, crossover study of a daily treatment dose of 3 mg melatonin or placebo given orally at 1700 hours in 8 healthy men. Semen quality (concentration, motility, and morphology), serum and seminal plasma 17-beta-estradiol (E(2)), testosterone, melatonin, and serum gonadotropin levels were determined every 3 months throughout the study. In 6 men, there was no change in semen quality or in serum and seminal plasma hormone levels during the study period. In 2 men, during the melatonin treatment period, sperm concentration decreased to 3 x 10(6)/mL and 12 x 10(6)/mL, and motility declined to 32% and 30%. These coincided with a decline in seminal plasma and serum E(2) levels and with an increase in testosterone:E(2) ratios. Six months after the cessation of melatonin, sperm concentration and motility were normal in 1 man but remained abnormal in the other one with a still elevated testosterone:E(2) ratio. Serum gonadotropin levels were unchanged during the study in all 8 men. Our preliminary observations suggest that long-term melatonin administration is associated with decreased semen quality in a number of healthy men, probably through the inhibition of aromatase at the testicular level.

Adult↗