Mouse homologues of the human AZF candidate gene RBM are expressed in spermatogonia and spermatids, and map to a Y chromosome deletion interval associated with a high incidence of sperm abnormalities

An RNA-binding motif (RBM) gene family has been identified on the human Y chromosome that maps to the same deletion interval as the 'azoospermia factor' (AZF). We have identified the homologous gene family (Rbm) on the mouse Y with a view to investigating the proposal that this gene family plays a role in spermatogenesis. At least 25 and probably >50 copies of Rbm are present on the mouse Y chromosome short arm located between Sry and the centromere. As in the human, a role in spermatogenesis is indicated by a germ cell-specific pattern of expression in the testis, but there are distinct differences in the pattern of expression between the two species. Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are female due to a position effect resulting in non-expression of Sry ; sex-reversing such mice with an Sry transgene produces males with a high incidence of abnormal sperm, making this the third deletion interval on the mouse Y that affects some aspect of spermatogenesis. Most of the copies of Rbm map to this deletion interval, and the Yd1males have markedly reduced Rbm expression, suggesting that RBM deficiency may be responsible for, or contribute to, the abnormal sperm development. In man, deletion of the functional copies of RBM is associated with meiotic arrest rather than sperm anomalies; however, the different effects of deletion are consistent with the differences in expression between the two species.      

Measurement of passive membrane parameters with whole-cell recording from neurons in the intact amphibian retina

1. Whole-cell recordings have been obtained from intact, photoactive retinal neurons using patch-clamp electrodes in the amphibian superfused retina eyecup preparation. 2. After removal of the vitreous humor from the surface of the retina, using a collagenase with low tryptic activity, high-resistance seals (1-10 G omega) could be formed between the patch pipette and the cell membrane by applying mild suction to the pipette. Additional suction broke the membrane patch and provided continuity between the low-resistance pipette and the interior of the neuron. 3. Measurements of input resistance and time constant were obtained from bipolar, amacrine, and ganglion cells. Assuming the membrane capacitance was 1 microF/cm2, time constant data were used to derive the specific membrane resistance. The average specific membrane resistance for the inner retinal neurons in our sample was 68,000 omega.cm2. 4. Analysis of the charging curve induced by a brief current pulse applied to the soma was used to analyze the average electrotonic length of dendrites. The charging curves of some ganglion cells were well represented by a single exponential, suggesting that they were essentially isopotential. 5. The voltage decay along an equivalent cylinder model of a ganglion cell was calculated, using the experimentally obtained values of membrane resistance to compute decay of steady-state voltages along the dendritic tree. The calculations indicate that with the high membrane resistance values implied by this study, the electrotonic length of dendritic cables were short, and there may be relatively little attenuation of the synaptic potentials irrespective of their location along the dendritic tree.     

A strain gauge device for measuring feeding or drinking in laboratory rats

The details of mechanical construction and electronic circuitry of a strain gauge system for continuously measuring food and water ingestion in laboratory rats are described. The system has been reliably tested over a number of years. It is eminently suitable for investigating daily rhythms in rat feeding and drinking behavior, where a large volume of data is collected over extended periods of time.     

The effect of ambient temperature cycles upon circadian running and drinking activity in male and female laboratory rats

The effect of a cycle of warm and cool ambient temperature (Ta) upon the free-running circadian running and drinking rhythms of male and female laboratory rats was investigated. Rats free-running in constant darkness and constant cool Ta (21 degrees C +/- 2 degrees C) were exposed to a 12:12 cycle of high (34 degrees C +/- 2 degrees C) and cool (21 degrees C +/- 2 degrees C) Ta. Three male rats and one female rat entrained to the Ta cycle. Ten of 12 male and 9 of 11 female rats exhibited post-Ta cycle phases not predictable from pre-Ta cycle phases. Most rats exhibited positive and negative masking of activity during the Ta cycle. Activity periods shortened for all rats during the Ta cycle, and male free-running periods lengthened upon cessation of the Ta cycle to values significantly greater than precycle periods. It was concluded that Ta acts as a weak zeitgeber in laboratory rats and has greater effects on males compared to females.     

Oligonucleotide fingerprinting of isolates of Candida species other than C. albicans and of atypical Candida species from human immunodeficiency virus-positive and AIDS patients.

Oligonucleotide fingerprinting of genomic DNA from oral isolates of four different Candida species other than C. albicans and atypical chlamydospore-positive isolates from human immunodeficiency virus (HIV)-positive individuals and AIDS patients was investigated as a means for differentiating between isolates within individual species. Oligonucleotides composed of simple repetitive sequence motifs, including (GACA)4, (GATA)4, (GGAT)4, (GTG)5, and (GT)8, all yielded fingerprints suitable for strain segregation of 8 C. tropicalis isolates, 12 Torulopsis (Candida) glabrata isolates, 8 atypical Candida isolates, and, except for (GATA)4, 2 C. krusei probe in turn and so generate several distinct DNA fingerprints of the same DNA sample. However, none of the probes yielded fingerprints suitable for strain segregation with three C. parapsilosis isolates. The (GATA)4 probe was also used to detect restriction fragment length polymorphisms among a genetically closely related group of atypical Candida isolates on primary isolation from an additional HIV-infected patient. These chlamydospore-positive atypical Candida isolates were sucrose positive, were of C. albicans serotype A, hybridized weakly with the C. albicans-specific mid-repeat sequence probe 27A, and yielded fingerprint profiles by random polymorphic DNA analysis that were distinct from those derived from C. albicans isolates. The C. stellatoidea ex-type strain NCPF 3108 was indistinguishable from the atypical Candida isolates in all these tests and also yielded an identical carbohydrate and nitrogen source assimilation profile by using the ID 32C yeast identification system.     

Use of hybridot assay to screen for BK and JC polyomaviruses in non-immunosuppressed patients.

Urine samples from 50 patients attending a genitourinary outpatient clinic and from 13 renal allograft recipients were investigated for evidence of infection with human BK and JC polyomaviruses using cytology and a new DNA hybridot assay. Forty four per cent of samples from the renal allograft recipients were positive by cytology and 75% by DNA hybridisation, indicating that hybridot assay is more sensitive than cytological screening. BK and JC viral DNA was found in 20% of the patients attending the genitourinary clinic, showing infection with BK virus and JC virus in a group of patients with clinical conditions not normally associated with immunological deficiency-a finding that has not been reported before.     

Terminal-Phase Chronic Myelogenous Leukemia: Approaches to Treatment

The prognosis of patients with CML has improved little in the past 50 years. The relatively benign chronic phase invariably deteriorates to a refractory and rapidly fatal terminal phase. This terminal stage has been found to have two major subtypes as defined by morphologic, cytochemical, immunologic, and enzymatic criteria--myeloblastoid and lymphoblastoid. Aggressive combination chemotherapy has achieved minimal improvement in survival once the terminal phase has begun, perhaps because only Ph1-positive stem cells remain to repopulate the marrow at this stage. Bone marrow transplantation has also been unsuccessful as therapy for the terminal phase, possibly because the patients are too debilitated to tolerate transplantation once the terminal phase has begun. Combination chemotherapy has been applied in an effort to eliminate the Ph1 chromosome-containing clone during the chronic phase. This goal has not yet been consistently achieved. Chemotherapy has also not been able to delay the onset of the terminal phase nor to prolong survival. Even in those patients in whom the Ph1 chromosome-containing clone has been eliminated, relapse to the chronic phase with return of the Ph1 chromosome has generally occurred within a brief period of time. Bone marrow transplantation during the chronic phase may hold the promise of true cure for CML, with permanent elimination of the malignant clone. However, the chronic phase can be unpredictably long and patients in the chronic phase often have few, if any symptoms. Therefore, there has been a reluctance to employ drastic therapy during the chronic phase. Techniques to predict the transformation to the terminal phase prior to overt morphologic or clinical conversion are now being developed. It may be possible in the future to attempt HLA-matched sibling donor bone marrow transplantation at the earliest signs of transformation from the chronic to the terminal phase. In this manner, optimal survival might be achieved by allowing patients to be maintained in the chronic phase for as long as possible prior to the initiation of aggressive therapy. Until this is routinely possible, continued research designed to improve the therapy of the terminal phase must be pursued. These attempts are likely to include the development and evaluation of new chemotherapeutic agents, novel methods of administration of existing drugs to better exploit their pharmacokinetics (for example, continuous infusion), and the utilization of newly described treatment approaches (such as the use of "differentiating" agents in an attempt to prevent progression to blastic transformation).(ABSTRACT TRUNCATED AT 400 WORDS)     

Factors affecting ventricular volumes determined by a count-based equilibrium method

Using a 99mTc-filled source ("ventricle") in an elliptical torso phantom, we analyzed the effect of source depth, region of interest (ROI) size, background concentration and source shape on volumes determined by an attenuation-corrected count-based equilibrium method. The calculated volume of a 96 cc sphere decreased linearly from 103 to 82 cc with increasing depth from 4 to 18 cm [vol = -1.48 X depth (cm) + 109, r = 0.99]. The calculated volume of the same sphere imaged at a depth of 9 cm increased from 98 to 117 cc with ROI sizes increasing from 161 to 1,369 pixels (1 pixel = 0.17 cm2). With increasing background concentration from 0-2 microCi/ml calculated volumes decreased from 95 to 85 cc (vol = -5.3 X background concentration (microCi/ml) + 95, r = 0.97). However, with correction for over-subtraction of background, increasing background activity caused no decrease in calculated volume (mean = 95 cc, s.d. = 1). Calculated volumes for the sphere and various cylinders were accurate, while those for cones were up to 37% lower for actual volumes ranging from 56-608 cc. This study demonstrates that multiple factors produce variability in count-based determination of phantom volumes. A careful consideration of the interaction of these factors with the edge-detection and computational algorithms is required.     

Effects of characteristic x-rays on assay of I-123 by dose calibrator

Large differences in dose-calibrator readings are obtained if "high-purity" I-123 is assayed in different containers. Large correction factors are necessary for assaying another isotope of iodine, I-125, in a dose calibrator, because of absorption of the low-energy (28.4-keV, weighted mean) emissions. We found that up to 70% of the dose-calibrator response to I-123 can be due to characteristic x-rays with energies exactly the same as those emitted by I-125, and that dose-calibrator response to I-123 is also strongly affected by the absorption properties of the vial. An appropriate method to define I-123 activity uses a gamma camera with a medium-energy collimator to establish correction factors for dose-calibrator assay of I-123 in different containers. Correction factors for a plastic syringe and a thick-wall glass vial, were determined using this method. Measurement of I-123 activity in a copper absorber will eliminate the response to x-rays, and the gamma camera is useful in establishing the necessary correction factors.