Baboon spermatozoa-zona pellucida binding assay

This study developed a baboon in vitro system that allows transport of sperm from a treatment facility to an off-site location for subsequent evaluation of sperm functional capacity. We further described a sperm functional assay that evaluates baboon sperm binding to homologous zona pellucida, a baboon hemizona assay (HZA). Semen samples were collected from baboons via electroejaculation directly into refrigeration transport buffer. Postshipment semen characteristics were analyzed and each specimen prepared for assessment of sperm-zona pellucida interaction. Optimization of the baboon HZA included determination of the relationship between motile sperm concentration and zona pellucida binding. The effect of the sperm activators, caffeine and dbcAMP, on computerized sperm motion characteristics and HZ binding was also determined. A significant motile sperm concentration dependent increase was observed in sperm-zona pellucida binding. Maximal binding was observed at approximately 1-2 million motile sperm/mL. Treatment with the sperm activators, caffeine and dbcAMP, resulted in a significant increase in sperm progressive motility, straightline velocity (VSL), and amplitude of lateral head displacement (ALH), p <0.05 and a highly significant increase in curvilinear velocity (VCL), p <0.01. Treatment with caffeine and dbcAMP was not an absolute requirement for sperm-zona pellucida binding, inasmuch as binding did occur in the absence of activators. However, treatment with the two activators, caffeine and dbcAMP, resulted in a highly significant increase in HZ binding, p <0.0001. This system allows for the short-term maintenance of baboon sperm in a semiquiescent state until stimulation with the activators, caffeine and dbcAMP. It further provides a novel approach to delineating a contraceptive regimen's or agent's (ie, sperm vaccine) impact on specific cellular events occurring in the male gamete during fertilization.

Adaptive decision making, ecological validity, and the frontal lobes

Existing neuropsychological procedures assess veridical, but not adaptive, decision making, which are based on different mechanisms. This severely curtails the tests' ecological validity, because most real-life decision making situations are adaptive, rather than veridical. Veridical decision making entails finding the correct response intrinsic to external situations and is actor-independent. Adaptive decision making is actor-centered and priority-based. Prefrontal cortex is critical for adaptive decision making. Innovative actor-centered decision-making tasks are required to better understand frontal lobe functions. We have designed a prototype for such procedures, the Cognitive Bias Task (CBT). CBT elicited strong gender and hemispheric differences in the effects of focal frontal lesions, which are more robust than those elicited with veridical tasks, such as the Wisconsin Card Sorting Test.

Task-specific deactivation patterns in functional magnetic resonance imaging

In general, image analysis of cognitive experiments using functional magnetic resonance imaging techniques has emphasized those regions of the brain where increases in signal intensity, with regard to the reference state, are associated with activation. Nevertheless, a number of recent papers have shown that there are areas of deactivation as well. In this study, we have used a univariate analysis and echo-planar functional magnetic resonance imaging to address the relationship of the reference state to the deactivations. We employed two dichotomous covert tasks, orthographic lexical retrieval and pure visual retrieval, to contrast with the reference state (baseline) of silent counting. Our analysis yielded extensive, task-specific landscapes of regional incremental and decremental responses. We have specifically demonstrated that the decremental responses are not due to activation in the reference state. We have also demonstrated that they are not an artifact of a specific part of the image analysis, and propose that they represent a physiological, task specific signal that should be considered an integral component of neural networks representing brain function.

Toronto street youth and HIV/AIDS: prevalence, demographics, and risks

PURPOSE

The purposes of this study were: (a) to identify human immunodeficiency virus (HIV) prevalence in Toronto street youth through paired blood and saliva specimens; (b) to identify the HIV risk and prevention behaviors of street involved youth; and (c) to identify demographic or other factors that may contribute to the risk of street youth becoming infected with HIV/acquired immunodeficiency syndrome (AIDS) in the future.

METHODS

This was a cross-sectional convenience study of street-involved youth aged 14-25 years. The youth participated in interviews to identify HIV-related knowledge and personal risk and preventive behaviors. Following interviews, they were asked to provide a saliva sample, blood spot, or both. They could refuse one or both samples without jeopardizing their involvement or receiving an honorarium. Two males were the only participants who declined to provide a sample.

RESULTS

Fifteen of 695 (2.2%) youth tested positive for HIV infection. All were male, ranging in age from 18 to 25 years. Same and opposite sex, intravenous (IV) drug use, prostitution, and incarceration were risk factors associated with positive HIV test results. The rate of HIV infection was seven times greater for the group 20 years of age and older (20-25) compared to the younger group aged 14-9 years. The proportion testing positive for HIV from small cities, towns, and rural communities in Ontario was 40%; yet, they represented 21% of the study population. Most (57%) youth had been on their own for no more than 3 years and had moved frequently. Nearly two thirds (60%) had stayed in hostels or homeless shelters in the previous 6 months.

CONCLUSION

Street youth in Canada are at high risk of HIV infection with their risk increasing with age. Unprotected (same and opposite) sex, IV drug use, prostitution and incarceration were linked to their HIV infections. The high level of mobility identified by street youth challenges governments, communities, and public health officials to develop appropriate prevention strategies and to carefully monitor the spread of HIV infection in this vulnerable population.

Adaptive versus veridical decision making and the frontal lobes

Adaptive decision making and veridical decision making are based on different mechanisms. Veridical decision making is based on the identification of the correct response, which is intrinsic to the external situation and is actor-independent. Adaptive decision making is actor-centered and is guided by the actor's priorities. The prefrontal cortex is particularly critical for adaptive decision making and less so for veridical decision making. However, most experimental procedures used in cognitive psychology and neuropsychology focus on veridical decision making and ignore adaptive decision making. Innovative experimental procedures are required to characterize the contribution of the prefrontal cortex to adaptive decision making. We have designed a prototype for such procedures, the Cognitive Bias Task, and present the novel findings generated by this task.

DNA-protein interactions in the CCAAT box region of the murine lactate dehydrogenase C promoter

Electrophoretic Mobility (EMSA), using oligonucleotides containing CCAAT box sequences from the murine Idhc promoter show the presence of CCAAT binding proteins in nuclear extracts from liver and testis. In a liver extract, a single shifted band is seen. However, in the testis extract, two shifts are observed, one of which may be due to a testis specific isoform of CCAAT binding factor (CBF). Southwestern analysis with an oligonucleotide probe containing these sequences reveals the presence of a protein of approximately 120 kD in the testis extract. In the liver extract, a 70-kD protein binds the probe. An antibody against HeLa CBF causes a supershift in testis nuclear extract.

Limits to the value of mental health review tribunals for offender patients. Suggestions for reform

BACKGROUND

Reform of mental health legislation for England and Wales is due. MHRTs offer an important check in the balance between patient and public rights.

AIMS

To study the quantity and outcome of MHRTs in special (high-security) hospitals.

METHOD

Data were extracted from the records of 1670 patients detained under mental illness or psychopathic disorder classifications in special hospitals during 1992.

RESULTS

There were 661 MHRT hearings, mostly requested by patients. Forty-three (7%) discharges were ordered, often without key data about continuing care in the written evidence. There were 56 recommendations for transfer to lesser security. Correlates of MHRT discharge were: female gender, younger age (in women), a legal classification of psychopathic disorder and shorter length of stay. Conditional discharge did not necessarily mean departure from special hospital.

CONCLUSIONS

Special hospital MHRTs result in few changes in patient status. A probable need for improvement in the evidence put before an MHRT was found. Legislation reformers should consider an extension of MHRT powers to order transfer between levels of security.

Transgenic mice demonstrate a testis-specific promoter for lactate dehydrogenase, LDHC

The mammalian genome encodes a family of lactate dehydrogenase (LDH) isozymes. Two of these, ldha and ldhb, are expressed ubiquitously. The ldhc gene is active only in the germinal epithelium during spermatogenesis. In our analysis of ldhc gene regulation, we found that a 60-base pair promoter sequence was sufficient for testis-specific expression in an in vitro transcription assay. To confirm these findings, a genomic fragment containing 100 base pairs overlapping the transcription start site was isolated and linked to the Escherichia coli lacZ gene. We report that this genomic fragment drives testis-specific expression in transgenic mice. We conclude that transcription of the transgene and possibly of the endogenous ldhc gene is restricted to leptotene/pachytene primary spermatocytes.

Wisconsin Card Sorting Test performance in above average and superior school children: relationship to intelligence and age

This study explores the relationship of intelligence and age to scores on the Wisconsin Card Sorting Test, a measure of executive function. A sample of 26 normal children with Wechsler Intelligence Scale for Children-III (WISC-III) Full-Scale IQS above 130 and 24 normal children with WISC-III Full-Scale IQS between 110 and 129 were administered the test. A comparison to published norms revealed that above average children outperformed the average 9- to 14-year-old child on every measure at every age. Multiple regression analyses statistically related the Wisconsin Card Sorting Test, perseverative, nonperseverative, total errors, and trials to the first category of intelligence. Intelligence proved to be a significant qualifier of age trends. Gender relationships were nonsignificant in a preliminary analysis.

Human testis-specific lactate dehydrogenase-C promoter drives overexpression of mouse lactate dehydrogenase-1 cDNA in testes of transgenic mice

The three isozymes of lactate dehydrogenase, each encoded by a separate gene, are developmentally regulated and differentially expressed in tissue-specific patterns. The lactate dehydrogenase-C (LDHC, mouse Ldh3) gene is temporally expressed exclusively in the germ line during spermatogenesis, whereas lactate dehydrogenase-A (LDHA, mouse Ldh1) and B (LDHB, mouse Ldh2) genes are active in somatic tissues. To determine, therefore, whether overexpression of Ldh1 would perturb spermatogenesis, we constructed a transgene in which a sequence from the promoter region of human LDHC was coupled with mouse Ldh1 cDNA. Among nine (three males, six females) founder lines that were identified as being transgenic for the construct, one male transmitted the gene through its germ line. Homo- and heterotetramers containing the LDH-A subunit were detected in homogenates of testes from transgenic animals. We conclude that the human LDHC promoter contains the necessary regulatory sequence(s) for specific expression of mouse Ldh1 as a transgene during spermatogenesis. The fertility of the founder animal was not impaired.

The effect of full-time faculty hospitalists on the efficiency of care at a community teaching hospital

BACKGROUND

Hospitalists are increasingly being used for inpatient care.

OBJECTIVE

To investigate whether the use of hospitalists is beneficial.

DESIGN

Retrospective cohort study.

SETTING

Inpatient medical service of a 500-bed community teaching hospital.

PARTICIPANTS

1620 patients in the study group, seen during the hospitalist year; 1679 patients from the same outpatient practice as the study group, seen during the previous year (prehospitalist year); an unselected comparison group of 3413 patients seen during the prehospitalist year and 3223 patients seen during the hospitalist year; and a subset of the unselected comparison group, cared for by outpatient practices, who had a prehospitalist length of stay similar to that of the study group (743 patients in the prehospitalist year and 786 in the hospitalist year).

INTERVENTIONS

Full-time faculty hospitalists cared for the study group, were in the hospital during normal working hours, and made decisions throughout the day. In the prehospitalist year and in the comparison groups, primary care physicians managed their own hospitalized patients.

MEASUREMENTS

Length of stay; cost of care; costs of hematology and chemistry evaluation, pharmacy, and radiology; and readmissions were determined for the prehospitalist and hospitalist years.

RESULTS

In the study group, median length of stay decreased from 6.01 to 5.01 days (P < 0.001). Median cost of care decreased from $4139 to $3552 (P < 0.001), and the 14-day readmission rate decreased from 9.9 to 4.64 readmissions per 100 admissions (P < 0.001). In the comparison groups, length of stay decreased but both cost of care and readmission rates increased.

CONCLUSION

Hospitalists may improve the efficiency of inpatient care. Further study in various settings is needed to verify these findings.

Expression of the human antigen SPAG2 in the testis and localization to the outer dense fibers in spermatozoa

ABSTRACT Antisperm antibodies (ASAs) have been implicated in some instances of infertility. To characterize sperm antigens relevant to immunologic and immunocontraceptive development, SPAG2 (sperm-associated antigen 2) was identified by screening a human testis cDNA library with human sera positive for ASAs. Subsequently, two isoforms, SPAG2-1 and SPAG2-2, were identified in testis and placenta libraries, respectively. In the current study, Southern analysis of human genomic DNA with a probe common to the two SPAG2 isoforms indicated a single SPAG2 gene; therefore, alternative splicing is a likely mechanism for production of variant mRNAs. In situ hybridization of human testis sections demonstrated the expression of SPAG2 in primary spermatocytes, with decreased or arrested expression in postmeiotic cells. Immunofluorescence of Triton X-100-extracted spermatozoa with an anti-SPAG2 peptide antiserum indicate that SPAG2 is an intracellular component of the sperm flagellum. Electron microscopy refined this localization to the outer dense fibers (ODFs), structural filaments associated with the mammalian sperm axoneme. The ODFs have been reported to be composed of keratin-like intermediate filament proteins. However, SPAG2 does not exhibit the molecular characteristics of such proteins, nor does SPAG2 demonstrate sequence homology with previously characterized ODF proteins. Therefore, SPAG2 represents a novel protein of human sperm ODFs. Characterization of SPAG2 will further our understanding of ODF function in normal sperm motility and of flagellar abnormalities that lead to male infertility.

Deoxyribonucleic acid-protein interactions and expression of the human testis-specific lactate dehydrogenase promoter: transcription factor Sp1 plays a major role

The human testis-specific lactate dehydrogenase c gene (ldh-c) shows an exceptionally large window of expression throughout pre- and postmeiotic stages of the male germ cell lineage. In order to characterize the multiple stage-specific transcription factors necessary for ldh-c expression, we previously characterized the human ldh-c core promoter. Here, we used a combination of gel retardation assays and an in vitro transcription system derived from human tissues to better define the elements that govern ldh-c transcription. Three classes of transcriptional regulators were defined by these experiments. 1) The Sp1 transcription factor is a testis-"enriched" protein that is absent from most somatic tissues and that appears to play a major role in determining ldh-c expression in the testis. Highest levels of Sp1 during spermatogenesis correlate with maxima of ldh-c expression. 2) The testis-specific cAMP response element modulator (CREM) transcription factor binds a cAMP response element (CRE)-like sequence located at position -433. This transcriptional activator might contribute to postmeiotic transcription of ldh-c. 3) Factors present in tissues negative for ldh-c expression appear to bind both the CRE-like sequence and an adjacent hormone response element. The presence of this element could be involved in regulating ldh-c through the glucocorticoid/androgen pathways at the early stages of ldh-c expression.

Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

Thermal unfolding of bacteriophage T4 short tail fibers

The short tail fibers of bacteriophage T4 are composed of a homotrimer of the product of gene 12 (P12) with a molecular weight of 165,000. P12 is capable of reconstituting defective phage particles lacking gene 12. After heating to 75 degrees C, P12 was able to retain 90% of its ability to reconstitute T412- particles. When heated above 75 degrees C, P12 was no longer capable of fully reconstituting defective phage particles. By 95 degrees C, the reconstitution efficiency of the P12 preparation was reduced by 4 orders of magnitude. Thermal unfolding was also monitored by heating the protein in the presence of SDS to freeze partially unfolded states; by protease hydrolysis; and by intrinsic fluorescence changes. Exposure to SDS had little effect for temperatures up to 55 degrees C, but by 65 degrees C, the reconstitution efficiency of P12 treated with 0.01% SDS dropped to less than 1% of the original titer. Thermolysin digestion of P12 heated to various temperatures showed that treated P12 started to inactivate before 45 degrees C and inactivation was essentially complete by 55 degrees C. Intrinsic fluorescence data of heated P12 indicated that the protein begins to unfold by 45 degrees C and exhibits distinct peak shifts at 60 degrees C and above 80 degrees C. We conclude that, in the absence of SDS or proteases, P12 heated to 75 degrees C can refold back to an active conformation. Trimeric P12 undergoes some irreversible denaturation between 75 and 85 degrees C, and heating between 85 and 95 degrees C results in dissociation of P12 into monomers.

Colinear synthesis of an antigen-specific B-cell epitope with a 'promiscuous' tetanus toxin T-cell epitope: a synthetic peptide immunocontraceptive

Carrier conjugation is commonly used to provide T-cell help for small, linear peptides containing antigen-specific B-cell epitopes. However, carrier conjugation is expensive, variable and often results in adverse side effects if the conjugate is administered repeatedly. To eliminate the need for carrier conjugation, we examined two synthetic peptides for their ability to elicit sustained antibody titres in female rabbits and baboons. One peptide (hC1-20) was based on the sequence of the sperm-specific isozyme of human lactate dehydrogenase (LDH-C4). This peptide stimulates helper T-cell responses. The other peptide (bC5-19:TT) was a chimera between an LDH-C4 B-cell epitope and a 'promiscuous' T-cell epitope from tetanus toxin which has been shown to bind to and stimulate many different major histocompatibility complex alleles. Both peptides were immunogenic in rabbits and baboons. The chimera elicited consistently high antibody titres and was immunogenic in 19/19 wild-caught female baboons. When 14 bC5-19:TT immunized baboons were mated, their fertility was reduced by 62% compared with controls (P < 0.02). This carrier-free construct can be incorporated into biodegradable microspheres which may provide long-term protection from pregnancy with a single dose.

Perseverative behavior in Alzheimer's disease and subcortical ischemic vascular dementia

Perseverative behavior has not been extensively studied in patients with dementia. In this study, perseverative behavior was elicited with the dementia version of the Graphical Sequence Test. A control group and participants with Alzheimer's disease (AD) and subcortical ischemic vascular dementia (IVD) were studied. A factor analysis revealed a 3-factor model consisting of perseverations related to semantic knowledge, motor functioning, and a third, intermediary factor. IVD participants made more total perseverations than did AD participants. Perseverations made by AD participants were correlated with deficits on tests of semantic knowledge, whereas the perseverations made by IVD participants were correlated with motor and frontal systems tests. Results are consistent with the view that perseverative behavior is hierarchically arranged in terms of specific levels of cognitive complexity and the overall pattern of cognitive deficits associated with each type of dementia.

Counseling sexually active teenagers treated with potential human teratogens

Adolescents with hemoglobinopathies need daily chelation therapy with drugs which are known or suspected to be teratogenic. The prevention of fetal exposure to such drugs is therefore a major task for health professionals caring for these patients. We describe a pilot program aiming to prevent pregnancy among sexually active adolescents treated with iron chelators in Toronto. Most of them had normal response to GnRH, suggesting endocrinologic fertility, and unlike the literature concerning their healthy peers, all sexually active patients in this study reported use of at least one form of contraception.

Isolation and characterization of a molecular chaperone, gp57A, of bacteriophage T4

A molecular chaperone of bacteriophage T4, gp57A, which facilitates the formation of the long and short tail fibers, was isolated and characterized by peptide analysis, sedimentation equilibrium, and circular dichroism (CD). Sequence analysis confirmed the predicted sequence of 79 amino acids from the nucleotide sequence of the gene with the N-terminal methionine removed. The result led to the conclusion that the apparent smaller molecular weight of 6,000 from Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis than the expected molecular weight of 8,710 was due to its abnormal electrophoretic behavior instead of cleavage or processing of the gene product. Estimation of the secondary structure from far-UV CD indicated a 94% alpha-helix content, which was in accord with the prediction from the primary structure. A sedimentation equilibrium study, on the other hand, revealed that gp57A assumes a tetrameric subunit structure.

Assessment of brain function in adolescent anorexia nervosa before and after weight gain

This study assessed brain function in 20 adolescent females with anorexia nervosa (AN) and 20 controls using event-related potentials (ERPs) and a battery of neuropsychological tests. In the AN group, N4 latencies for a nonverbal memory task were significantly longer than for a verbal task, and P3 latencies for the verbal task were significantly longer among anorexics as compared to controls. On the nonverbal task, the AN group failed to show a right > left hemispheric asymmetry for P3 amplitudes which was observed for controls. These group differences for P3 latency and amplitude were particularly pronounced in the central-parietal region of the head. Body Mass Index (BMI) in the anorexic group significantly predicted N4 amplitudes for the verbal task in the left hemisphere and P3 amplitudes for the nonverbal task in the right hemisphere. The two groups did not differ on any of the tests used to assess neuropsychological functioning. Eight nutritionally recovered patients and their matched controls were retested using the same procedures. Anorexics showed larger P3 amplitudes for the verbal as compared to the nonverbal task at follow-up. These findings provide evidence for localized brain dysfunction in anorexia nervosa that only partially normalizes with weight gain.

Cloning, sequencing, and characterization of LDH-C4 from a fox testis cDNA library

A full-length cDNA encoding the sperm-specific enzyme lactate dehydrogenase-C4 was isolated from a fox testis cDNA expression library and sequenced. The deduced translated protein sequence was shown to be 86% identical to that of human LDH-C4. In the fox testis, mRNA encoding LDH-C4 was first detected in pachytene spermatocytes. The LDH-C4 protein monomer was identified in Western blots of sperm membrane extracts as having a molecular weight of approximately 35,000, consistent with the monomeric size of this subunit previously identified in sperm from other species. The LDH-C4 protein is localized on the sperm plasma membrane overlying the principal piece of the tail. Based on the available sequence data, we were able to identify an epitope within the N-terminal region of the LDH-C4 amino-acid sequence which when administered to female foxes is antigenic and produces antibodies capable of recognizing the native protein.