InGaP electron spectrometer for high temperature environments.

In this work, a 200 µm diameter InGaP (GaInP) p+-i-n+ mesa photodiode was studied across the temperature range 100 °C to 20 °C for the development of a temperature-tolerant electron spectrometer. The depletion layer thickness of the InGaP device was 5 µm. The performance of the InGaP detector was analysed under dark conditions and then under the illumination of a 183 MBq 63Ni radioisotope beta particle source. The InGaP photodiode was connected to a custom-made low-noise charge-sensitive preamplifier to realise a particle counting electron spectrometer. Beta spectra were collected at temperatures up to 100 °C with the InGaP device reverse biased at 5 V. The spectrum accumulated at 20 °C was compared with the spectrum predicted using Monte Carlo simulations; good agreement was found between the predicted and experimental spectra. The work is of importance for the development of electron spectrometers that can be used for planetary and space science missions to environments of high temperature or extreme radiation (e.g. Mercury, Jupiter's moon Europa, near-Sun comets), as well as terrestrial applications.

Temperature effects on an InGaP (GaInP) 55Fe X-ray photovoltaic cell.

This paper investigates the effects of temperature on an InGaP (GaInP) 55Fe X-ray photovoltaic cell prototype for a radioisotope microbattery (also called a nuclear microbattery). An In0.5Ga0.5P p-i-n (5 µm i-layer) mesa photodiode was illuminated by a standard 206 MBq 55Fe radioisotope X-ray source and characterised over the temperature range -20 °C to 100 °C. The electrical power output of the device reached its maximum value of 1.5 pW at a temperature of -20 °C. An open circuit voltage and a short circuit current of 0.82 V and 2.5 pA, respectively, were obtained at -20 °C. While the electrical power output and the open circuit voltage decreased with increasing temperature, an almost flat trend was found for the short circuit current. The cell conversion efficiency decreased from 2.1% at -20 °C to 0.7% at 100 °C.

Role of Defects and Surface States in the Carrier Transport and Nonlinearity of the Diode Characteristics in PbS/ZnO Quantum Dot Solar Cells.

The roles of bulk surface states and interfacial defects are probed experimentally using a combination of current-voltage, capacitance-voltage, and impedance measurements. The critical importance of the quality of both the film and interfaces is evident in current-voltage measurements where shunting and interface states result in large dark currents and the subsequent loss of Jsc. These properties are shown to be critically related to the nature and role of the PbS QD interface with the (nominally) ohmic gold contact. Specifically, the nonideality of this interface results in the formation of an electric field and therefore a Schottky barrier that opposes the transport of carriers across the conventional ZnO-PbS CQD system. Nonidealities in the structure and absorber layer are also reflected in nonmonotonic behavior and dispersion in C-V measurements with trapping processes on the CQD surfaces, and the ZnO/PbS and PbS/Au interfaces also affecting the carrier dynamics, which is reflected in the response time of these systems under different biases.

AlGaAs 55Fe X-ray radioisotope microbattery.

This paper describes the performance of a fabricated prototype Al0.2Ga0.8As 55Fe radioisotope microbattery photovoltaic cells over the temperature range -20 °C to 50 °C. Two 400 µm diameter p+-i-n+ (3 µm i-layer) Al0.2Ga0.8As mesa photodiodes were used as conversion devices in a novel X-ray microbattery prototype. The changes of the key microbattery parameters were analysed in response to temperature: the open circuit voltage, the maximum output power and the internal conversion efficiency decreased when the temperature was increased. At -20 °C, an open circuit voltage and a maximum output power of 0.2 V and 0.04 pW, respectively, were measured per photodiode. The best internal conversion efficiency achieved for the fabricated prototype was only 0.95% at -20 °C.

Selective estrogen receptor modulators: from bench to bedside and back.

OBJECTIVE: To provide a brief review of the history of the development of selective estrogen receptor modulators (SERMs), the current data assessing the effect of SERMs at the organ level, and the mechanism of action of these agents. METHODS: All the pertinent medical literature was reviewed, and the effects of SERMs on various end-organs were summarized. RESULTS: SERMs have been available for clinical use since the late 1960s. By the late 1980s, several SERMs had become available that influenced clinical practice. Multiorgan effects of these compounds include variable clinical efficacy for treatment of menopausal symptoms involving the central nervous system, variable effects on the genitourinary tract, and, in general, positive effects on serum lipid levels. SERMs seem to affect bone density positively, albeit to variable degrees, depending on the agent being used. The greatest effect of SERMs has been on the breast, and current SERMs seem to have efficacy for prevention of breast cancer as opposed to the controversial effect of estrogen on the breast. Disadvantages of SERMs include exacerbation of menopausal symptoms and, as with estrogen, an increased incidence of venous thrombosis and pulmonary emboli. SERMs act by modifying the configuration of the estrogen receptor. Effects at the gene transcription level seem to be tissue specific, a factor that likely accounts for the variability of clinical action seen. CONCLUSION: SERMs are a viable option for treatment of various problems associated with menopause.

Successful pregnancy in a woman with lipoatrophic diabetes mellitus. A case report.

BACKGROUND: Lipoatrophic diabetes mellitus is a rare insulin-resistance syndrome. A successful pregnancy occurred in a woman with lipoatrophic diabetes with no antepartum or intrapartum complications except hypertriglyceridemia, treated with gemfibrozil. CASE: A 29-year-old primigravida had lipoatrophic diabetes most consistent with congenital partial lipodystrophy (Kobberling-Dunnigan syndrome). The antenatal course was remarkable only for a midtrimester rise in serum triglycerides. The patient underwent oxytocin induction and an uncomplicated vaginal delivery. CONCLUSION: This case demonstrates that women with lipoatrophic diabetes who are otherwise healthy should not be discouraged from trying to conceive. Blood lipids should be checked periodically and hypertriglyceridemia treated to prevent pancreatitis. Gemfibrozil was used in this patient without apparent adverse effects.

When a thyroid abnormality is palpable. What it means and what you should do.

Clinicians faced with a palpable thyroid abnormality should ascertain whether there is evidence of thyroid dysfunction, concern for malignancy, and symptoms of obstruction. In the vast majority of cases, laboratory assessment of the thyroid with an sTSH assay establishes the presence or absence of thyroid dysfunction. In a nodular thyroid gland, fine-needle aspiration biopsy is the method of choice for determining whether malignancy is present. In a large goiter, the presence of obstructive symptoms or findings may be a clear indication that surgery is needed. The absence of these findings may warrant simple observation.

Treatment of established postmenopausal osteoporosis with raloxifene: a randomized trial.

Raloxifene is a selective estrogen receptor modulator that in experimental animals acts as an estrogen receptor antagonist in breast and endometrium but as an estrogen receptor agonist in the skeletal and cardiovascular systems. We conducted a 1-year prospective, randomized, double-blind trial in 143 postmenopausal osteoporotic women (mean +/- SD age, 68.4+/-5.0 years) with at least one prevalent vertebral fractures and low bone mineral density (BMD), comparing groups receiving raloxifene at 60 mg/day (RLX60) or 120 mg/day (RLX120) and a control group receiving supplements of 750 mg/day of calcium and 400 IU/day of vitamin D. There were no differences among groups in the occurrence of uterine bleeding, thrombophlebitis, breast abnormalities, or increased endometrial thickness (assessed by ultrasonography). As compared with controls, the changes in values over 1 year for RLX60 and RLX120, respectively, were significant for serum bone alkaline phosphatase (-14.9%, -8.87%), serum osteocalcin (-20.7%, -17.0%), and urinary C-telopeptide fragment of type I collagen/creatinine (-24.9%, -30.8%), markers of bone turnover; for serum total cholesterol (-7.0% for RLX60) and low density lipoprotein cholesterol (LDL) (-11.4% for RLX60) and for the LDL/HDL cholesterol ratio (-13.2%, -8.3%). BMD increased significantly in the total hip (1.66% for RLX60) and ultradistal radius (2.92%, 2.50%). There were nonsignificant trends toward increases over controls in BMD for lumbar spine, total body, and total hip (for RLX120). Using a >15% cutoff definition, raloxifene had no effect on incident fractures, but using a >30% cutoff, there was a dose-related reduction (p = 0.047). We conclude that raloxifene therapy is well tolerated, reduces serum lipids, and does not stimulate the uterus or breasts. It has beneficial effects on bone, although, under the conditions of this study, these appear to be of a smaller magnitude than have been reported with estrogen therapy.

Pamidronate: an unrecognized problem in gastrointestinal tolerability.

Pamidronate (aminohydroxypropylidine bisphosphonate, APD) is an effective agent for treatment of Paget's disease of bone, and it has also been thought to be effective for treatment of osteoporosis. We desired to study a newer, time-release preparation of pamidronate, and carried out a placebo-controlled, double-masked study of postmenopausal osteoporosis. The original formulation was in a rapidly dissolving gelatin capsule. We encountered four episodes of esophagitis in 49 enrolled patients. We therefore discontinued treatment with this preparation and later began the study again using a standard tablet preparation. We encountered an additional case of erosive esophagitis in 1 patient of 40 receiving this tablet preparation. No patient was receiving concomitant medication which could cause esophagitis. Two of the patients gave a past history of hiatal hernia and 1 gave a history of gastric ulcer 27 years previously. The diagnosis of esophagitis was confirmed in all cases by endoscopy. Healing of the esophagitis promptly ensued after discontinuation of the pamidronate and the use of antacid medication.

Thoracoscopic excision of a peripheral corticotropin-secreting pulmonary carcinoid tumor.

Bronchial carcinoid tumors are rare neuroendocrine neoplasms that arise from the Kulchitsky cells of the bronchial epithelium. These tumors can manifest as central carcinoid tumors, pulmonary carcinoid tumorlets, or peripheral carcinoid tumors. Occasionally, the peripheral carcinoid tumors produce corticotropin and result in Cushing's syndrome. Herein we report the first case of Cushing's syndrome associated with a peripheral pulmonary carcinoid tumor that was excised by video-assisted thoracoscopy. After excision, the patient had complete remission. Video-assisted thoracoscopy may be ideal for resecting a peripheral pulmonary carcinoid, especially in patients with debilitation but no evidence of metastasis.

Congenital gigantism due to growth hormone-releasing hormone excess and pituitary hyperplasia with adenomatous transformation.

The cause of gigantism in most patients is a GH-secreting pituitary tumor. In this report, a case of congenital gigantism due to probable central hypersection of GH-releasing hormone (GHRH) is described. Normal at birth (4.4 kg; 53 cm), our 7-yr-old male patient grew progressively thereafter to attain a height of 182 cm and a weight of 99.4 kg at the time of our evaluation. The markedly increased baseline plasma levels of GH (730 micrograms/L) did not suppress during a standard 3-h oral glucose tolerance test, but did increase 54% after iv infusion of GHRH. Baseline plasma levels of insulin-like growth factor-I, PRL, and immunoreactive GHRH were also markedly increased. Computed imaging of the head showed a large, partially cystic sellar and suprasellar mass. Extensive imaging studies did not localize a potential source of GHRH. Preoperative treatment with octreotide and bromocriptine for 4 months resulted in a 25% reduction of suprasellar tissue mass. The pituitary tissue removed at transsphenoidal and transfrontal operations showed massive somatotroph, lactotroph, and mammosomatotroph hyperplasia. Areas of GH- and PRL-secreting cell adenomatous transformation were also evident. No histological or immunohistochemical evidence of a pituitary source of GHRH was found. The peripheral plasma immunoreactive GHRH concentration remained unaffected by pharmacological and surgical interventions. We suspect that a congenital hypothalamic regulatory defect may be responsible for the GHRH excess in this case.

Resection of select mediastinal parathyroid adenomas through an anterior mediastinotomy.

Two patients who had undergone thorough surgical exploration of the neck were found to have adenomas of fifth parathyroid glands within the mediastinum. After localization with computed tomographic scanning or thallium-technetium imaging, or both, these tumors were resected through a parasternal approach (anterior mediastinotomy); thus, median sternotomy was obviated. This approach has not been described previously for the removal of mediastinal parathyroid tumors.

Case report 653: Arthritis of the wrist due to Mycobacterium avium-intracellulare.

We present a case of arthritis of the wrist in an elderly man due to Mycobacterium avium-intracellulare. Prior steroid injections and a surgical procedure on the affected wrist were predisposing risk factors for subsequent mycobacterial involvement of the skeleton. Radiographs demonstrated findings characteristic of tuberculous arthritis: particularly, osteopenia with marginal erosions and diffuse lytic lesions involving the carpals, proximal metacarpals, and distal ends of the radius and ulna. MR scans showed soft-tissue involvement and extensive marrow replacement consistent with infection. It is to be reemphasized that the clinical and radiological findings in this case are very often indistinguishable from TB. The diagnosis depends on the results of tissue culture. Since radiologists are likely to be involved increasingly in interpreting images of immunocompromised patients afflicted with a variety of both typical and atypical infections, it is important occasionally to report rare infections such as that described herein.

Diagnosis of corticotropin-producing bronchial carcinoid tumors causing Cushing's syndrome.

Cushing's syndrome due to ectopic production of adrenocorticotropic hormone (corticotropin) has been recognized for many years. Traditionally, clinicians have thought that most cases were due to lung carcinomas and that the clinical manifestations differed from those for pituitary-dependent Cushing's syndrome. We report two cases of corticotropin-producing bronchial carcinoid tumors that were clinically and biochemically indistinguishable from pituitary-dependent Cushing's syndrome. Review of the literature revealed that bronchial carcinoid tumors are the most common cause of Cushing's syndrome due to ectopic secretion of corticotropin. On biochemical and anatomic studies, they are frequently indistinguishable from pituitary-dependent Cushing's syndrome and thus may be difficult to diagnose. Inferior petrosal sinus sampling for corticotropin and computerized imaging of the chest may be the best aids in making the diagnosis.

Insulinoma in a patient with annular pancreas.

Intraoperative ultrasonography has facilitated the localization of insulinomas. In this report, we describe a patient who was found to have an insulinoma in association with an annular pancreas. Because such tumors can be in close approximation to major pancreatic ductal structures, intraoperative ultrasonography can be useful for not only localizing the lesion but also delineating the related anatomic features. Although the optimal management of an asymptomatic annular pancreas has not been determined, our patient had no evidence of chronic pancreatitis and no narrowing of the duodenal lumen; therefore, no bowel bypass procedure was done.

The pituitary gland in the Laurence-Moon syndrome.

The apparent hypogonadism in patients with the Laurence-Moon syndrome has been variably attributed to unresponsiveness of target organs to gonadal hormones, primary end-organ failure, hypothalamic dysfunction, or pituitary failure. We report the first immunocytologic study of the pituitary gland in this rare disorder. No morphologic abnormalities were noted. The numbers and immunoreactivities of adenohypophyseal cell types were normal. No microscopic abnormalities were evident in the hypothalamus and target organs. The results of our study are consistent with recent biochemical data that suggest that pituitary function is normal in patients with this syndrome.

The hypothalamus and pituitary in cerebral gigantism. A clinicopathologic and immunocytochemical study.

Cerebral gigantism, or Sotos' disease, is a rare disorder of unknown cause characterized by the early onset of excessive growth, acromegalic features, and some degree of mental retardation. Although several endocrinologic abnormalities have been described in such patients, none has been specific or sufficient to explain the clinical features. Our report of the endocrinologic and pathologic aspects in a young woman with Sotos' disease includes the first microanatomic study of the hypothalamus and immunocytochemical examination of the pituitary gland in this disorder.