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.

A dual-function palindromic sequence regulates testis-specific transcription of the mouse lactate dehydrogenase c gene in vitro

The promoter of the mouse lactate dehydrogenase c (Ldh-c) gene was assayed in an in vitro transcription system. Of the nuclear extracts isolated from several mouse tissues, only testis supported transcription from a 710 Ldh-c promoter fragment. Mutation analysis indicated that a canonical TATA box and a 30-bp palindromic sequence are both required for promoter activity. Liver nuclear extract (LN) can reduce transcriptional activity significantly when added to testis nuclear extract (TN). Deletion of the 3' palindromic sequence resulted in a low level of transcriptional activity in LN. Competition with a double-stranded synthetic palindromic oligonucleotide inhibited transcription in TN and rescued a low level of transcription in LN. Our results strongly indicate that the palindromic sequence contains both a negative element for repression in somatic tissues and a positive element for activation of the Ldh-c gene in testis.

Posttranscriptional regulation of primate Ldhc mRNA by its AUUUA-like elements

The Ldhc locus encodes the testis-specific isozyme of lactate dehydrogenase in mammals. In our efforts to understand the regulatory mechanisms involved in expression of Ldhc, we recognized the possibility that this gene could be post-transcriptionally regulated in certain species as the 3'-untranslated region (3'-UTR) of Ldhc in primates, but not rodents, contains a number of AU-rich motifs and is conserved. To determine whether the primate Ldhc mRNA is posttranscriptionally regulated, comparison of baboon and mouse Ldhc mRNA stability was made in a cell-free system. The results indicated that the baboon mRNA is labile, while that of mouse, which does not contain the AU-rich motifs, is highly stable. Consistent with these results, the steady state level of primate Ldhc was found to be 8 to 12 fold lower than that of the mouse. We show that in a transformed murine germ cell line, the human Ldhc mRNA is moderately unstable, and removal of its 3'-UTR leads to stabilization of the mRNA. Mutations disrupting the AU-rich motifs of human Ldhc result in stabilization of the mRNA in vitro. On the basis of these observations, we conclude that stability of the primate Ldhc transcript is regulated by dispersed AU-rich elements found in its 3'-UTR. Because AU-rich motifs similar to these are found in many mRNAs, these findings may have broad implications.

Rise and fall of modular orthodoxy

The premise of cortical modularity is based on strong dissociations caused by focal lesions. These dissociations are rare, and their explanatory power and theoretical importance are vastly overrated. The effects of brain lesions must be considered in their totality, rather than in idiosyncratic selectivity. These effects are more consistent with a continuous, graded functional neocortical geometry, than with a modular neocortex. Distinction must be drawn between strong intrinsic modularity, and weak emergent modularity. Strong intrinsic modularity is more characteristic of the thalamus than of the cortex. The advent of neocortex may have represented an evolutionary escape from strong modularity as the dominant principle of neural organization, and a shift toward a more interactive principle of neural organization dominated by emergent properties. The latter may take the form of weak modularity, reflective of cognitive skill routinization. The extent of weak, emergent modularization may be asymmetric, more pronounced in the left hemisphere, while the right hemisphere is essentially amodular.

Total quality management of a medical residency

Although many hospitals have begun the long and difficult process of adapting to the concepts of total quality management, few have reported efforts to apply total quality management to a medical residency. We report here the initial results of the Western Pennsylvania Hospital's efforts, as part of the hospital's conversion of its management structure to total quality management.

Expression profile of Ldh-a in the developing rat (Rattus norvegicus) testis suggests regulation at the translational level

Expression of Ldh-a and Ldh-c mRNAs was examined in the rat testis. The mRNA levels of both Ldh-a and Ldh-c increase during testicular maturation. In the adult testis, Ldh-a mRNA is expressed maximally in primary spermatocytes. Comparison of the Ldh-a mRNA expression profile with its translation product suggests that this gene is translationally down-regulated during spermatogenesis.

Reversible contraception in female baboons immunized with a synthetic epitope of sperm-specific lactate dehydrogenase

In previous experiments, the sperm-specific isozyme of lactate dehydrogenase (LDH-C) had been purified from mouse testes and shown to suppress the fertility of female baboons by 70% compared to controls. Although these results demonstrated the feasibility of this approach for contraceptive vaccine development, it is not practical to purify enough of the protein from natural sources for human use. Therefore, a need exists to develop a contraceptive vaccine based on synthetic peptides. In the current study, baboon LDH-C cDNA was amplified by the reverse transcriptase-polymerase chain reaction technique. The amino acid sequences of human and baboon LDH-C were 99.3% identical, indicating that the human LDH-C would be an effective antigen in nonhuman primates. The immunodominant epitope of human LDH-C was identified, synthesized, and conjugated to diphtheria toxoid (DT). This construct was used to immunize 15 female baboons; 15 control animals were immunized with DT alone. The fertility of the experimental group was reduced by 75% as compared to the controls (p < 0.02). One year after the last immunization, the contraceptive effect was completely eliminated (no statistical difference between the groups). These results show that a synthetic peptide based on the sequence of human LDH-C is effective in preventing pregnancy in nonhuman primates. The effect is completely reversed 1 yr after the last immunization. The contraceptive effect is not related to serum antibody titers, and human LDH-C is only slightly more effective than mouse LDH-C in female baboons.