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.

The CpG-rich promoter of human LDH-C is differentially methylated in expressing and nonexpressing tissues

A comparison of nucleotide sequences of murine Ldh-a and Ldh-c genes and human LDH-A, LDH-B, and LDH-C reveals that mouse Ldh-c has lost the CpG "island" present in the genes for the somatic isozymes. However, the human LDH-C gene has a CpG-rich region of 230 bp surrounding its promoter. Endonuclease sensitivity coupled with polymerase chain reaction (PCR) demonstrate the presence of nine heavily methylated sites in this region in different somatic cells. The same sites are specifically hypomethylated in expressing tissues. 3' sites bordering the CpG-rich region appear to be methylated in both expressing and nonexpressing tissues. Furthermore, the methylated promoter forms a specific complex in vitro with a methyl-DNA binding protein. Evolutionary and functional implications of these observations are discussed.

Recurrent deletions involving chromosomes 1, 5, 17, and 18 in colorectal carcinoma: possible role in biological and clinical behavior of tumors

We have employed cytogenetic and restriction fragment length polymorphism (RFLP) analysis to identify a full spectrum of cytogenetic and molecular alterations associated with initiation and progression of "sporadic" colorectal cancer and also to correlate the alterations with biological and clinical behavior of the tumors. The study series included 63 colorectal cancers, 47 primary and 16 metastatic recurrences. Cytogenetic analysis was successful in 48 tumors (76%) of which 44 (91%) were abnormal. Of these 44 tumors, clonal abnormalities were identified in 43, whereas chromosomes from one tumor were unsuitable for complete analysis. Each of these abnormal tumors displayed heterogeneity with regard to extent and complexity of recurrent chromosomal abnormalities. Numerical losses of chromosomes 17 and 18 (20-34%) and gains of chromosome 7 (28%) were significantly higher. The four most frequent structural rearrangements on the other hand, involved specific regions of chromosomes 1p, 5q, 17p, and 18q. The shortest regions of overlap of these rearrangements or losses were located at 1p36, 5q21-22, 17p13 and 18q21- > ter. RFLP analysis directed at 1p, 5q, 17p and 18q identified allelic deletions of these regions in 39 tumors (64%) which included 17 normal and 11 cytogenetic failures. Of all the informative tumors, 32%, 37%, 31%, and 63% showed allelic losses at chromosomes 1p, 5q, 17p and 18q respectively. The two methods of analysis (cytogenetics and RFLP) employed to identify genetic alterations were complementary; probes for chromosome 1 and 18 showed the greatest degree of concordance, whereas probes for chromosomes 5 and 17 provided relatively higher rate of discordance with cytogenetic results. These differences could be attributed mainly to three reasons: 1) a limited number of probes used for RFLP analysis; 2) contamination of tumor cells with normal cells, and 3) either mutational inactivation or deletion of specific alleles not closely linked to the probes used. Regardless of these limitations, however, the combined use of cytogenetic and RFLP identified genetic alterations in a large number of tumors and help elucidate the role of hyperdiploidy and/or relative deficiency of a given chromosomal segment in expression of recessive mutations. In addition, alterations of either chromosomes 1 or 17 predicted poorer survival for the patients with primary colorectal cancer (p = 0.03).

The Cognitive Bias Task and lateralized frontal lobe functions in males

The Cognitive Bias Task (CBT) is a multiple-choice response selection paradigm characterized by inherent ambiguity. All items offer a range from extremely context-dependent to extremely context-invariant responses. Lateralized prefrontal lesions produce extreme, and opposite, response biases on CBT in right-handed males. Healthy control subjects perform in the middle range. Findings suggest a dynamic balance between two synergistic decision-making systems in the frontal lobes: context-dependent in the left hemisphere and context-invariant in the right. The robust lateralized effects, which are dependent on task ambiguity, are sensitive and specific to frontal dysfunction. CBT is discussed in comparison with the Wisconsin Card Sorting Test as a potential cognitive activation task for functional neuroimaging of the frontal lobes.

Clustering of six human 11p15 gene homologs within a 500-kb interval of proximal mouse chromosome 7

Homologs of genes mapping to human chromosome 11p15 are located in three distinct, widely separated regions of mouse chromosome 7 (Mmu7). To date, six genes have been localized to the most proximal HSA11p15/Mmu7 homology region, including Ldh3 (encoding lactate dehydrogenase C), Ldh1 (lactate dehydrogenase A), Myod1 (myogenic differentiation factor-1), Tph (tryptophan hydroxylase), Saa1 (serum amyloid-A-1), and Kcnc1 (encoding a Shaw-type voltage-gated potassium channel). To define the overall size and organization of this region of Mmu7, we have established a long-range physical map including the murine Ldh1, Ldh3, Saa, Tph, Kcnc1, and Myod1 genes. Our results demonstrate that these six genes are physically clustered and are distributed throughout a 500-kb interval located just proximal of the pink-eyed dilution (p) locus. These data, together with recent mapping studies within the related region of HSA11p15, demonstrate that gene content and organization within this proximal homology segment have been highly conserved throughout evolution.

A 60-bp core promoter sequence of murine lactate dehydrogenase C is sufficient to direct testis-specific transcription in vitro

A clone containing the 5' flanking region of the testis-specific murine lactate dehydrogenase C (Ldhc) gene was isolated from a mouse genomic library. Promoter activity was demonstrated within a 720-bp fragment in testis nuclear extract (TN). Interestingly, the addition of liver nuclear extract (LN) significantly repressed Ldhc promoter activity in the transcription assay system. Sequence analysis of this promoter region revealed several ubiquitous cis-regulatory elements, including one TATA box, one GC box, and two putative CCAAT elements. Analysis of a series of deletion mutants revealed that a 60-bp core promoter sequence was sufficient to direct basal, testis-specific transcription in an in vitro transcription system. A 103-kDa protein in TN and a 65-kDa protein in LN bind to the same palindromic sequences within the 60-bp core promoter region.

Immortalized germ cells undergo meiosis in vitro

Establishing mammalian germ-cell lines capable of differentiation in vitro would greatly facilitate the study of gametogenesis and the meiotic process that is so fundamental for reproduction and the maintenance of genetic diversity of the species. We have established two germ-cell lines [GC-2spd(ts) and GC-3spc(ts)] by cotransfecting primary mouse testicular germ cells with the simian virus 40 large tumor antigen gene and the gene coding for a temperature-sensitive mutant of p53. Both cell lines express the germ cell-specific lactate dehydrogenase C4 isozyme and cytochrome ct isoform. At the permissive temperature of 37 degrees C, the GC-2spd(ts) line generates cells with a haploid DNA content and morphologic and biochemical features of round spermatids, including the appearance of an acrosomic granule. The identification of a flagellar axoneme when these cells are cultured at 32 degrees C further indicates that these cells correspond to the early spermatid stages of spermiogenesis.

Hypercarotenemia and transaminitis in female adolescents with eating disorders: a prospective, controlled study

PURPOSE

Hypercarotenemia and transaminitis are reported as laboratory features of anorexia nervosa. However, the specificity and sensitivity of an elevation in serum carotene and transaminase are not known. Therefore, a prospective study was undertaken to determine the clinical utility of these serum markers.

METHODS

Serum carotene was measured in 46 female adolescents between 13 years and 18 years of age (21 anorexia nervosa, 17 bulimia nervosa, 8 unclassified eating disorders). Findings were compared to levels of carotene in serum samples obtained from similarly aged females with either chronic inflammatory bowel disease (22 Crohn disease, 11 ulcerative colitis) or acute medical symptoms not associated with undernutrition or intestinal inflammation (N = 26), and 21 children of either sex with dyspeptic symptoms.

RESULTS

Serum carotene was elevated in 6/46 (13.0%) females with eating disorders compared with only 2/80 (2.5%) children in the three comparison groups (p < 0.01). Hypercarotenemia was present in 4/21 girls with anorexia nervosa compared with 0/17 females with bulimia nervosa (p = 0.11). Transaminitis was present in 38.5% (AST) and 7.7% (ALT) of eating disorder patients. Liver enzyme abnormalities, however, did not correlate with hypercarotenemia. Transaminitis was also not specific for eating disorders since transaminitis was observed with comparable frequency in the three comparison groups.

CONCLUSIONS

These findings confirm that hypercarotenemia is a laboratory feature in some subjects with eating disorders, in particular, anorexia nervosa. The low sensitivity (13.0%) does not provide justification for its use as a screening test. However, in complicated diagnostic settings a serum carotene determination could prove useful because the specificity (97.5%), positive predictive value (75.0%), and negative predictive value (66.1%) of an elevated carotene were high. These data also show that elevated carotene levels are not associated with hepatic abnormalities. Although transaminitis is reported as a laboratory feature of eating disorders, the prevalence of such abnormalities in this study was not higher than in age-matched comparison groups.

Characterization of a human antigen with sera from infertile patients

We report the cDNA cloning and subsequent characterization of a novel antigen implicated in antibody-mediated human infertility. This antigen, designated AgX (unknown antigen), was identified originally by screening a human testis lambda gt11 cDNA expression library with infertile patients' sera known to contain anti-sperm antibodies. AgX cDNAs isolated from testis and placenta cDNA libraries (AgX-1 and AgX-2, respectively) differed by a 48-bp deletion in the open-reading frame (ORF). The AgX-1 and AgX-2 ORFs encoded putative peptide chains of 505 and 521 amino acids (approximately 55.5 and approximately 57.3 kDa), respectively. The AgX amino acid sequences contained consensus motifs indicative of NTP binding. However, computer homology searches did not identify any significant similarity with known sequences. Quantitative analysis using the reverse transcriptase-polymerase chain reaction (RT-PCR) indicated that the AgX-1 mRNA was fiftyfold more abundant than AgX-2 in the testis, while AgX-2 was more abundant than AgX-1 in somatic tissues. An anti-AgX peptide antiserum identified two AgX isoforms on Western blots of human tissue extracts. An abundant 56-kDa isoform was detected only in testis and sperm. These data suggest that the 56- and 58-kDa isoforms are AgX-1 and AgX-2, respectively. AgX was localized by immunofluorescence to the principal piece of the sperm tail. Therefore, antibodies against an AgX isoform may reduce fertility by affecting sperm function.

Identification of a mutation at codon 65 in the IKKK motif of reverse transcriptase that encodes human immunodeficiency virus resistance to 2',3'-dideoxycytidine and 2',3'-dideoxy-3'-thiacytidine

The technique of in vitro selection was used to generate variants of the human immunodeficiency virus type 1 that are resistant to 2',3'-dideoxycytidine (ddC). Most of the pol regions of such viruses, including the complete reverse transcriptase open reading frame and portions of flanking protease and integrase genes, were cloned and sequenced, using PCR-based procedures. Mutations were variously detected at amino acid site 65 (Lys-->Arg; AAA-->AGA) and at a previously reported codon, site 184 (Met-->Val; ATG-->GTG). We introduced the site 65 mutation into the pol gene of infectious, cloned HxB2-D DNA by site-directed mutagenesis in order to confirm by viral replication assay the importance of this site in conferring resistance to ddC. The recombinant virus possessed greater than 10-fold resistance against this compound in comparison with parental HxB2-D. Cross-resistance of approximately 20- and 3-fold, respectively, was detectable against the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine and 2',3'-dideoxyinosine but not against 3'-azido-3'-deoxythymidine. Combinations of the site 65 and 184 mutations did not yield levels of resistance higher than those attained with the site 65 mutation alone. The presence of the site 65 mutation was confirmed by PCR analysis of peripheral blood mononuclear cells from patients on long-term ddC therapy in 4 of 11 cases tested. Viruses that possessed a ddC resistance phenotype were isolated from subjects whose viruses contained the site 65 mutation in each of four instances. Four of these clinical samples were also demonstrated to possess the Met-184-->Val mutation, and one of them possessed both the Lys-65-->Arg and Met-184-->Val substitutions. Direct cloning and sequencing revealed the site 65 mutation in viruses isolated from these individuals.

Human testis cDNAs identified by sera from infertile patients: a molecular biological approach to immunocontraceptive development

Sera from patients with known or suspected immunological infertility were used to screen a human testis cDNA library. A total of 59 sera detected 38 unique cDNA inserts of which four were testis specific by Northern blot analyses. One of these is a testis-specific isoform of calpastatin. Five additional clones, although not testis specific, were found to be testis abundant. The number and type of clones identified by these human sera suggests a possible aetiology for immunologic infertility. The testis-specific clones will be further characterized to establish their usefulness as contraceptive vaccine candidates.

Lateralization of frontal lobe functions and cognitive novelty

The two hemispheres are functionally different in ways not adequately captured by the classic distinction between linguistic and nonlinguistic processes. The right hemisphere is critical for processing novel cognitive situations. The left hemisphere is key to the processes mediated by well-routinized representations and strategies. The left frontal systems appear to be critical for the cognitive selection driven by the content of working memory and for context-dependent behavior, the right frontal systems for cognitive selection driven by the external environment and for context-independent behavior. The crucial role of the right hemisphere in processing cognitively novel situations underscores the importance of the right frontal systems in task orientation and in the assembly of novel cognitive strategies.

Activity of peptidergic neurons in the amygdala during sexual behavior in the male rat

The medial amygdaloid nucleus (AME) occupies a central position in the circuitry that organizes sexual behavior in the male rat. It receives a projection from olfactory structures that are activated by pheromonal cues indicating receptivity in the female and projects in turn to limbic and hypothalamic structures that are thought to organize aspects of coitus. Electrical stimulation of the AME elicits a behavioral state that is indistinguishable by several measures from the post-ejaculatory interval. We used chronic single-unit recording techniques to determine the behavioral conditions in which the AME is normally active. We found that the cells indeed fired selectively during the presence of a receptive female, but that the discharge considerably anticipated copulation in time. We propose that sexual behavior in the male rat is a reaction chain of fixed action patterns, each one acting as a releaser for the next. The AME mediates an early event in the reaction chain, namely recognition of the receptive female, but electrical activation of the AME causes the reaction chain to proceed to its culminating behavior, the post-ejaculatory interval.