Effects of daily melatonin injections on female reproduction in the white-footed mouse, Peromyscus leucopus

Seventy laboratory-reared (16L:8D at 21°) Peromyscus leucopus were injected daily for 7 weeks with either saline, 0.5, 5.0, or 50 μg of melatonin at either 2 or 12 hr into the photophase. Mice injected with 50 μg at 12 hr exhibited a substantial decrease (P < 0.01) in relative reproductive tract weight (2.3 ± 0.4 mg/g body wt) when compared to saline injected animals (4.6 ± 0.9). Seven out of the nine melatonin-treated mice also exhibited an imperforate vagina. A lesser effect was noted at lower melatonin concentrations. No regression occurred in mice injected 2 hr into the photophase. Thermoregulatory characters (nesting, brown fat, winter molt) were not affected by melatonin injections. In a second experiment 49 mice were injected with 50 μg of melatonin at either 7.5, 10, 14, 15, 18, or 23 hr after lights on. A gradual antigonadal effect was observed with a peak during late photophase. Mice injected during early scotophase (18 hr) exhibited little antigonadal effects of melatonin, but animals injected at 23 hr had reproductive tract weights which were considerably less (P < 0.05).     

Predictors of failure to attend scheduled mammography appointments at a Public Teaching Hospital

Objective: To identify patient, institutional, and physician characteristics that predict failure to attend scheduled mammography appointments. Design: Retrospective chart review. Setting: Medicine clinic at an urban public teaching hospital. Patients: All 907 women aged 40 years and more scheduled for mammography from March 1990 to June 1991. Measurements and main results: The main outcome measure was whether a woman kept her scheduled mammography appointment. Potential predictor variables included patient age, race, marital status, and insurance status; waiting interval to obtain a mammography appointment; and physician gender, level of training, country of training, and native language. The rate of failed mammography appointments was 23%. Univariate analysis showed that appointment failure was associated with age (p=0.03), with the lowest failure rates (19%) among women aged 60 years and more. Appointment keeping varied significantly by race (p=0.01), largely because of the higher failure rate among Native American women (36%). Insured women had a failure rate of 22% vs 33% for uninsured women (p=0.01). The rate of failed appointments varied significantly by waiting interval (p=0.05), with a peak failure rate of 27% for appointments scheduled 14–27 days in advance. None of the physician variables was associated with appointment failure. Multivariate analysis confirmed these results. Conclusions: Interventions to improve completion of breast cancer screening should include additional efforts targeted at groups with high rates of appointment failure, such as women under the age of 60, the uninsured, and Native Americans. Long waiting intervals to obtain mammography appointments may decrease compliance. Presented in part at the annual meeting of the Society of General Internal Medicine, Washington, DC, April 30, 1992. Supported by research grant CA 52994 from the National Cancer Institute, Bethesda, Maryland. Dr. Margolis was supported by an American Cancer Society Cancer Control Career Development Award for Primary Care Physicians. Dr. Lurie is a Henry J. Kaiser Family Foundation Scholar in General Internal Medicine.     

Hazards of non coherent light sources as determined by the framework of IEC TR-60825-9

An overview is provided of the scope and application of IEC TR 60825-9 in determination of hazards of non coherent optical radiation sources. Specific areas reviewed in detail include those relating to hazards of ultraviolet radiation, retinal thermal hazard and blue light photochemical hazard. The effect of spectral temperature on relative risk relating to retinal thermal hazard and blue light photochemical hazard are outlined. Assessment of risk factors of these hazards was determined using a range of measurement devices including spectral radiometer, broad band power meter and a locally developed device for determination of pulse profile of pulsed light sources.     

Storage of platelet concentrates using ion exchange resin charged with dibasic phosphate.

Platelet concentrates were prepared at twice the normal concentration and stored at room temperature for 7 days in either standard bags (controls) or bags to which 1 or 2 g of Amberlite resin beads charged with dibasic phosphate had been added. The resin beads served as a buffer system by providing a "slow release" form of phosphate ions as well as by binding CO2 produced during platelet metabolism. Control platelets demonstrated rapid falls in pH, ATP content, morphology score, and thrombin-induced nucleotide release after 24 hr of storage with a fall in pH to less than 6.0 by day 3. Profound ultrastructural changes and a rise in pO2, suggesting loss of platelet viability, accompanied these changes. In contrast, the resin-stored platelets remained near normal after 24 hr of storage, with preservation of discoid morphology, 95% of ATP levels, excellent ultrastructural appearance, and evidence of continued oxygen consumption after 3 days of storage. Even after 7 days of storage, ATP levels remained greater than 50% of baseline and ultrastructurally intact platelets were seen. In the 1-g resin bags the pH remained at baseline levels (6.9-7.0), while there was a rise in pH in the 2-g resin bags. These results demonstrate the beneficial effects of maintaining a higher pH during platelet storage and provide a new approach to studying the metabolic changes that occur during longer term storage.     

New abnormalities in the morphology, cell surface receptors, and electrolyte metabolism of In(Lu) erythrocytes

The In(Lu) phenotype is inherited as an autosomal dominant trait and is characterized by suppression of the Lutheran, P1, i, and Aua erythrocyte blood group antigens. We have developed a monoclonal antibody (L21) that strongly agglutinates all erythrocytes except In(Lu), and we have identified eight In(Lu) individuals among 42,000 blood donors tested. Studies of two families confirmed the dominant mode of inheritance and revealed several new features of this phenotype. The erythrocytes of all five affected individuals from the two families exhibited diminished hemagglutination by the lectin concanavalin A, although they reacted normally with several other lectins. The erythrocytes of two affected individuals in one family exhibited marked acanthocytosis. The erythrocytes of the proposita of the other family exhibited a mild degree of poikilocytosis, but the cells of the other two affected individuals in this family had normal morphology. The osmotic fragility of fresh In(Lu) erythrocytes was normal, but after incubation for 24 hours at 37 degrees C in plasma the In(Lu) cells exhibited a marked increase in resistance to osmotic lysis. During the incubation period the erythrocytes lost K+ and their total cation content was diminished. These data indicate that in addition to the suppression of blood group antigens noted previously, the In(Lu) phenotype includes a variety of morphological abnormalities and a defect in electrolyte metabolism. The use of L21 and similar monoclonal antibodies provides a more sensitive means of detecting In(Lu) erythrocytes than typing with human anti-Lub antisera.     

Recurrent Spontaneous Paresthesia in the Upper Limb Could Be Due to Migraine: A Case Series

Transient neurologic dysfunction is a characteristic feature of migraine. About 20% of migraineurs may experience various symptoms in the absence of any headache at one time or another. Visual auras are the most common auras of migraine, and migraine is considered as the most common cause of transient vision loss in young patients. Sensory auras are the second most common migrainous auras. However, the literature is silent for isolated sensory aura as a migraine equivalent. Herein we report 14 patients with recurrent episodic paresthesia in the limbs and other body parts. All patients fulfilled the diagnostic criteria of “typical aura without headache” of ICHD‐3β. All patients were subjected to various investigations to rule out secondary causes. Ten patients received antimigraine drugs and all showed a positive response to therapy. Recurrent spontaneous paresthesia is quite common in the general population and many patients remain undiagnosed. We speculate that a subset of patients might be related to migrainous sensory auras.