Acidification of intracellular pH in bovine spermatozoa suppresses motility and extends viable life

Intracellular pH (pHi) was determined in ejaculated bovine spermatozoa using a ratiometric absorbance technique under various incubation conditions that drastically altered sperm motility. The pHi was directly correlated with sperm motility. In a medium of Sodium, Potassium, and Magnesium [NKM] that supported active sperm motility, pHi was 6.9. In medium containing weak acids (NKM equilibrated with 100% CO2 or containing 80 mM 5,5-dimethyl-2,4-oxazolidinedione; DMO), pHi was depressed at least 0.5 pH unit and sperm motility was suppressed. After complete immobilization of sperm was established, removal of the weak acids indicated that suppression of motility was fully reversible for up to 48 hours in CO2 and up to 24 hours in DMO. This study shows that expression and conservation of sperm motility are inversely related, and that depression of pHi by weak acids can reversibly inhibit sperm motility. These findings may help to explain the mechanisms by which sperm are immobilized within the male reproductive tract, and could be applicable to the design of improved ambient temperature semen extenders.

Clinical and hemodynamic performance of the Toronto SPV bioprosthesis

BACKGROUND AND AIM OF THE STUDY

By providing a superior hemodynamic profile, the stentless valve design allows ventricular remodeling and may improve patient survival after aortic valve replacement (AVR). Compared with stent-mounted prostheses, implantation is more complex and requires a longer ischemic time; this may adversely affect surgical risk, especially if patients are elderly or require a concomitant procedure. The mid-term clinical and hemodynamic performance of the Toronto SPV bioprosthesis in a predominantly elderly patient group was analyzed.

METHODS

A total of 123 patients (median age 72 years) underwent AVR with the Toronto SPV. Concomitant procedures (mainly coronary artery bypass grafting, CABG), were performed in 60 patients (49%). Clinical details were recorded, with 100% follow up (total 317 patient-years). Hemodynamic evaluation, by serial echocardiography, was performed at four and 18 months after implantation.

RESULTS

The early mortality rate was low (0.8%). Mean (+/- SD) actuarial survival at 53 months was 78 +/- 5.9%, with most patients (91%) in NYHA classes I and II. Freedom from valve-related complications were: endocarditis 93.8 +/- 2.3%, thromboembolism 90.3 +/- 3.7% and bleeding 95.8 +/- 1.8%; there were no structural failures. The valve hemodynamic profile was excellent for all sizes: peak gradient 8.8 +/- 4.3 mmHg, effective orifice area 1.9 +/- 0.54 cm2 with significant improvement in left ventricular fractional shortening.

CONCLUSION

In this patient population the Toronto SPV was a suitable choice. Advanced age, a requirement for concomitant procedures and increased ischemic times did not adversely affect surgical risk. AVR with the Toronto SPV provided an excellent hemodynamic profile, and improved both left ventricular function and NYHA functional class.

Identification of PTE2, a human peroxisomal long-chain acyl-CoA thioesterase

Computer-based approaches identified PTE2 as a candidate human peroxisomal acyl-CoA thioesterase gene. The PTE2 gene product is highly similar to the rat cytosolic and mitochondrial thioesterases, CTE1 and MTE1, respectively, and terminates in a tripeptide sequence, serine-lysine-valine(COOH), that resembles the consensus sequence for type-1 peroxisomal targeting signals. PTE2 was targeted to peroxisomes and recombinant PTE2 showed intrinsic acyl-CoA thioesterase activity with a pH optimum of 8.5. A comparison of PTE2 and PTE1 thioesterase activities across multiple acyl-CoA substrates indicated that while PTE1 was most active on medium-chain acyl-CoAs, with little activity on long-chain acyl-CoAs, PTE2 displayed high activity on medium- and long-chain acyl-CoAs. The identification of PTE2 therefore offers an explanation for the observed long-chain acyl-CoA thioesterase activity of mammalian peroxisomes.

Transfer of nonassisted hatched and hatching human blastocysts after in vitro fertilization

OBJECTIVE

To determine the feasibility of performing blastocyst transfer 6 days after oocyte insemination.

DESIGN

Retrospective clinical study.

SETTING

University-based IVF center.

PATIENT(S)

All cases of IVF over a 1-year span of time (June 1998-1999) in which seven 2PN embryos were available for transfer.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation, pregnancy, and multiple pregnancy rates.

RESULT(S)

Transfer of blastocysts on days 5 and 6 resulted in implantation rates of 69% and 33% (P=0.0006), clinical pregnancy rates of 89% and 59% (P=0.05), and multiple pregnancy rates of 39% and 10% (P=0.03), respectively. In cases in which blastocysts were spontaneously hatching or hatched on day 6 (9% of embryos), implantation and pregnancy rates were 52% and 80%, respectively. Embryos were successfully frozen in the hatched or hatching state with resultant clinical pregnancies.

CONCLUSION(S)

Transfer of embryos can be delayed to day 6 after oocyte insemination at which time a small percentage of embryos will hatch. Hatching of embryos by day 6 is a favorable prognostic factor for IVF outcome. Embryos that fail to hatch by day 6 may have a lower implantation potential. Difficulty with hatching embryos sticking to the transfer catheter was not encountered. Furthermore, hatching and hatched embryos can be frozen and with subsequent transfer result in pregnancies.

Eating disorders in adolescent females with and without type 1 diabetes: cross sectional study

OBJECTIVE

To determine the prevalence of eating disorders in adolescent females with type 1 diabetes mellitus compared with that in their non-diabetic peers.

DESIGN

Cross sectional case-control led study.

SETTING

Diabetes clinics and schools in three Canadian cities.

SUBJECTS

356 females aged 12-19 with type 1 diabetes and 1098 age matched non-diabetic controls.

MAIN OUTCOME MEASURE

Eating disorders meeting Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria.

RESULTS

Eating disorders that met DSM-IV criteria were more prevalent in diabetic subjects (36, 10%) than in non-diabetic controls (49, 4%) (odds ratio 2.4, 95% confidence interval 1.5 to 3.7; P<0.001). Subthreshold eating disorders were also more common in those with diabetes (49, 14%) than in controls (84, 8%) (odds ratio 1.9, 95% confidence interval 1.3 to 2.8; P<0.001). Mean haemoglobin A(1c) concentration was higher in diabetic subjects with an eating disorder (9.4% (1.8)) than in those without (8.6% (1.6)), P=0.04).

CONCLUSIONS

DSM-IV and subthreshold eating disorders are almost twice as common in adolescent females with type 1 diabetes as in their non-diabetic peers. In diabetic subjects, eating disorders are associated with insulin omission for weight loss and impaired metabolic control.

Comparison of three salivary flow rate assessment methods in an elderly population

Measuring salivary flow rates among the frail elderly is a challenge. The currently used spit collection method requires levels of time and cooperation that often may exclude the frail elderly who are at high risk for salivary compromise. A measurement method that is not only valid and reliable, but also feasible and acceptable is needed for use in population studies of compromised adults. This study compared two salivary flow rate assessment methods using a suction machine against the currently accepted spit collection method in an elderly population aged 75 and older. Three methods of flow rate (g/min) assessment were compared at three time periods among 16 elders (mean age 86.6 years). Flow rates using the 2-min open suction method compared well with the 10-min spit method (r=0.778) but the 2-min closed suction method did not (r=0.158). Reliability evaluation of the open suction method and the spit method was assessed using a test/retest with a 1-week interval. Both methods demonstrated good comparable reliability (spit method r=0.566, P=0.01); open suction method, (r= 0.861, P<0.01). Based on a short survey questionnaire about the three methods, 11 of the 16 elderly subjects preferred the use of the suction machine to the spit method. These results indicate that the 2-min open suction method technique is a valid and reliable means of measuring salivary flow. The lower level of patient cooperation needed, the shorter time period required, and this preliminary report of its acceptability support the use of this method in future population studies of frail elders.

Simultaneous transhiatal esophagectomy and coronary artery bypass grafting without cardiopulmonary bypass

A 69-year-old patient underwent simultaneous transhiatal esophagectomy for carcinoma of the esophagogastric junction and benign spindle cell gastric tumor and coronary artery bypass grafting without cardiopulmonary bypass. A standard technique of transhiatal esophagectomy was used. The long saphenous vein was grafted to the left anterior descending artery and to the distal circumflex artery. The total theatre time was 6.5 h and the total ischemic time was 19 min. The patient made a good recovery and was discharged on day 18. He is enjoying an active lifestyle 6 months post-operatively.

Primary squamous carcinoma of the thyroid

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PriA and phage T4 gp59: factors that promote DNA replication on forked DNA substrates microreview

The initiation of DNA synthesis on forked DNA templates is a vital process in the replication and maintenance of cellular chromosomes. Two proteins that promote replisome assembly on DNA forks have so far been identified. In phage T4 development the gene 59 protein (gp59) assembles replisomes at D-loops, the sites of homologous strand exchange. Bacterial PriA protein plays an analogous function, most probably restarting replication after replication fork arrest with the aid of homologous recombination proteins, and PriA is also required for phage Mu replication by transposition. Gp59 and PriA exhibit similar DNA fork binding activities, but PriA also has a 3' to 5' helicase activity that can promote duplex opening for replisome assembly. The helicase activity allows PriA's repertoire of templates to be more diverse than that of gp59. It may give PriA the versatility to restart DNA replication without recombination on arrested replication forks that lack appropriate duplex openings.

Identification and characterization of HAOX1, HAOX2, and HAOX3, three human peroxisomal 2-hydroxy acid oxidases

Computer-based approaches identified three distinct human 2-hydroxy acid oxidase genes, HAOX1, HAOX2, and HAOX3, that encode proteins with significant sequence similarity to plant glycolate oxidase, a prototypical 2-hydroxy acid oxidase. The products of these genes are targeted to peroxisomes and have 2-hydroxy acid oxidase activities. Each gene displays a distinct tissue-specific pattern of expression, and each enzyme exhibits distinct substrate preferences. HAOX1 is expressed primarily in liver and pancreas and is most active on the two-carbon substrate, glycolate, but is also active on 2-hydroxy fatty acids. HAOX2 is expressed predominantly in liver and kidney and displays highest activity toward 2-hydroxypalmitate. HAOX3 expression was detected only in pancreas, and this enzyme displayed a preference for the medium chain substrate 2-hydroxyoctanoate. These results indicate that all three human 2-hydroxy acid oxidases are involved in the oxidation of 2-hydroxy fatty acids and may also contribute to the general pathway of fatty acid alpha-oxidation. Primary hyperoxaluria type 1 (PH1) is caused by defects in peroxisomal alanine-glyoxylate aminotransferase, the enzyme that normally eliminates intraperoxisomal glyoxylate. The presence of HAOX1 in liver and kidney peroxisomes and the ability of HAOX1 to oxidize glyoxylate to oxalate implicate HAOX1 as a mediator of PH1 pathophysiology.

The mouse neurological mutant flailer expresses a novel hybrid gene derived by exon shuffling between Gnb5 and Myo5a

Exon shuffling is thought to be an important mechanism for evolution of new genes. Here we show that the mouse neurological mutation flailer (flr) expresses a novel gene that combines the promoter and first two exons of guanine nucleotide binding protein beta 5 (Gnb5) with the C-terminal exons of the closely linked Myosin 5A (MyoVA) gene (Myo5a). The flailer protein, which is expressed predominantly in brain, contains the N-terminal 83 amino acids of Gnb5 fused in-frame with the C-terminal 711 amino acids of MyoVA, including the globular tail domain that binds organelles for intracellular transport. Biochemical and genetic studies indicate that the flailer protein competes with wild-type MyoVA in vivo, preventing the localization of smooth endoplasmic reticulum vesicles in the dendritic spines of cerebellar Purkinje cells. The flailer protein thus has a dominant-negative mechanism of action with a recessive mode of inheritance due to the dependence of competitive binding on the ratio between mutant and wild-type proteins. The chromosomal arrangement of Myo5a upstream of Gnb5 is consistent with non-homologous recombination as the mutational mechanism. To our knowledge, flailer is the first example of a mammalian mutation caused by germ line exon shuffling between unrelated genes.

Ethnic minority psychology in the 20th century: reflections and meditations on what has been and what is next

The launching of a new journal on ethnic minority psychology is placed in the context of events of the 20th century that precede it and make it possible. Citing the Dulles conference in 1978 on the role of ethnic minority issues in psychology, the author describes how the creation of the American Psychological Association (APA's) Office of Ethnic Minority Affairs and related governance structures made the creation of APA Division 45 (Society for the Psychological Study of Ethnic Minority Issues) possible, and hence their journal, Cultural Diversity and Ethnic Minority Psychology. Issues of conflict and cooperation among ethnic minority groups are discussed as the challenge to create unity from diversity is faced. Consideration of the steady increase in doctorally trained ethnic minority psychologists, relevant research, and organizational structures provides a basis for a publication outlet for these ideas. The challenges for ethnic minority psychology in the 21st century include research on the cultural diversity underlying ethnic minority groups and the similarities revealed by these differences, as well as the differences themselves. The new journal must fulfill the broad promise of the psychological study of ethnic minority issues on which Division 45 was founded.

PEX19 binds multiple peroxisomal membrane proteins, is predominantly cytoplasmic, and is required for peroxisome membrane synthesis

Peroxisomes are components of virtually all eukaryotic cells. While much is known about peroxisomal matrix protein import, our understanding of how peroxisomal membrane proteins (PMPs) are targeted and inserted into the peroxisome membrane is extremely limited. Here, we show that PEX19 binds a broad spectrum of PMPs, displays saturable PMP binding, and interacts with regions of PMPs required for their targeting to peroxisomes. Furthermore, mislocalization of PEX19 to the nucleus leads to nuclear accumulation of newly synthesized PMPs. At steady state, PEX19 is bimodally distributed between the cytoplasm and peroxisome, with most of the protein in the cytoplasm. We propose that PEX19 may bind newly synthesized PMPs and facilitate their insertion into the peroxisome membrane. This hypothesis is supported by the observation that the loss of PEX19 results in degradation of PMPs and/or mislocalization of PMPs to the mitochondrion.

Using videotaped specimens to test quality control in a computer-assisted semen analysis system

OBJECTIVE

To determine the feasibility of using semen samples previously recorded on videotape for intralaboratory and interlaboratory quality control of computer-assisted semen analysis (CASA) systems.

DESIGN

Blinded, controlled study.

SETTING

Pooled semen specimens from two normal human volunteers in an academic research environment.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Semen parameters from a videotape analyzed internally and by four external laboratories.

RESULT(S)

Preliminary experiments designed to examine intralaboratory variation by repeated analysis of semen samples recorded on videotape revealed some significant differences for every variable examined. When these data were analyzed by using the larger biologic error caused by subsampling, no significant differences were found for any of the variables examined. When either a standard set or the specific laboratories' sets of parameters were used to analyze the same videotaped semen specimen, no statistically significant differences were detected for sperm concentration for motility among the five laboratories after the biological error caused by subsampling was applied to results.

CONCLUSION(S)

These data strongly suggest that videotaped semen specimens can serve as quality control for intralaboratory and interlaboratory testing of CASA equipment as long as the biologic error caused by subsampling is used to compare results.

A prospective study of primary care patients with musculoskeletal pain: the identification of predictive factors for chronicity

Primary care faces the challenge of reducing the proportion of patients continuing with musculoskeletal pain beyond the acute phase. This study assessed patients presenting in general practice with a four- to 12-week history of pain and re-assessed them 12 weeks later. Patients whose pain was described as 'none' or 'slight' were allocated to the 'acute group', and those whose pain continued to be 'moderate' or 'severe' were allocated to the 'chronic group'. Comparative analysis of the two groups' responses at initial assessment identified pain intensity, active coping score, and previous pain episode to be factors independently predictive of chronicity.

Using the metabolism of PAHs in a human cell line to characterize environmental samples

P450 reporter gene system (RGS) is an in vitro assay to detect compounds that activate the Ah receptor and induce cytochrome P450 (CYP1A1). This system utilizes a human cell (101L) stably transfected with a luciferase reporter downstream of human CYP1A1 promoter sequences. When CYP1A1-inducing compounds are present, luciferase is produced as well as endogenous CYP1A1 enzymes. Polycyclic aromatic hydrocarbons (PAHs) are more readily degraded than chlorinated compounds including dioxins, furans, and coplanar polychlorinated biphenyls (PCBs). PAH-induced luciferase production begins to decrease between 6 and 16 h, while chlorinated compounds produce a more sustained response. Individual and mixtures of CYP1A1-inducing compounds were tested at both 6 and 16 h. Extracts of soils containing both PAHs and dioxins were also tested, before and after cleanup to remove PAHs. Results indicate that RGS testing at 6 and 16 h is a promising tool to differentiate between PAHs and chlorinated hydrocarbons often co-occurring in environmental samples.

Great pains: famous people with headaches

Have headaches influenced the course of history? It is very difficult to prove, but there is no doubt that head pains have affected some of the most influential people in history. This review explores how headaches have affected some of the world's most famous people.

Duplex opening by primosome protein PriA for replisome assembly on a recombination intermediate

PriA and other primosome assembly proteins of Escherichia coli recruit the major replicative helicase DnaB for replisome assembly during bacteriophage Mu transposition and replication. MuA transposase catalyzes the transfer of Mu ends to target DNA, forming a potential replication fork that provides the assembly site for the replisome. However, this fork lacks the single-stranded DNA needed to load DnaB. Although no pre-existing primosome assembly sites that bind PriA were found within the Mu end sequences, PriA was able to bind to the forked DNA structure created by MuA. The helicase activity of PriA could then open the duplex to create the DnaB binding site. In a tightly coupled reaction on synthetic forked substrates, PriA promoted both the unwinding of the lagging strand arm and preprimosome assembly to load DnaB onto the lagging strand template. PriA apparently translocated 3' to 5' along the lagging strand template until sufficient single-stranded DNA was exposed for binding of DnaB, which then translocated 5' to 3' in the opposite direction. Mutant PriA lacking helicase activity was unable to promote this process, and loss of PriA helicase impaired Mu DNA replication in vivo and in vitro. This suggests that the opening of the duplex by PriA helicase is a critical step in the initiation of Mu DNA replication. Concerted helicase and primosome assembly functions would allow PriA to act as initiator on recombination intermediates and stalled replication forks. As part of the replisome, PriA may act as a mobile initiator that minimizes interruptions in chromosomal replication.

Identification of peroxisomal acyl-CoA thioesterases in yeast and humans

A computer-based screen of the Saccharomyces cerevisiae genome identified YJR019C as a candidate oleate-induced gene. YJR019C mRNA levels were increased significantly during growth on fatty acids, suggesting that it may play a role in fatty acid metabolism. The YJR019C product is highly similar to tesB, a bacterial acyl-CoA thioesterase, and carries a tripeptide sequence, alanine-lysine-phenylalanineCOOH, that closely resembles the consensus sequence for type-1 peroxisomal targeting signals. YJR019C directed green fluorescence protein to peroxisomes, and biochemical studies revealed that YJR019C is an abundant component of purified yeast peroxisomes. Disruption of the YJR019C gene caused a significant decrease in total cellular thioesterase activity, and recombinant YJR019C was found to exhibit intrinsic acyl-CoA thioesterase activity of 6 units/mg. YJR019C also shared significant sequence similarity with hTE, a human thioesterase that was previously identified because of its interaction with human immunodeficiency virus-Nef in the yeast two-hybrid assay. We report here that hTE is also a peroxisomal protein, demonstrating that thioesterase activity is a conserved feature of peroxisomes. We propose that YJR019C and hTE be renamed as yeast and human PTE1 to reflect the fact that they encode peroxisomal thioesterases. The physical segregation of yeast and human PTE1 from the cytosolic fatty acid synthase suggests that these enzymes are unlikely to play a role in formation of fatty acids. Instead, the observation that PTE1 contributes to growth on fatty acids implicates this thioesterase in fatty acid oxidation.

Heterozygosity of p21WAF1/CIP1 enhances tumor cell proliferation and cyclin D1-associated kinase activity in a murine mammary cancer model

The p21(WAF1/cIP1) cyclin-dependent kinase (cdk) inhibitor is a regulator of the G(1)-S cell cycle checkpoint. Despite the importance of p21 in cell cycle inhibition, its role as a tumor suppressor is uncertain. p21 mutations are infrequent in human tumors, and p21 null mice exhibit no increased tumor incidence. To ascertain whether p21 could influence tumor formation or progression in the context of other oncogenic stimuli, we crossed p21-deficient mice with mammary tumor susceptible Wnt-1 transgenic mice. The p21+/+, p21+/-, and p21-/- Wnt-1 transgenic female offspring were monitored for mammary tumor incidence and growth rates. p21 status had no effect on the age at which mammary tumors formed. However, p21+/- mammary tumors grew significantly faster than p21+/+ and p21-/- mammary tumors. The increased growth rates were confirmed by mitotic index counts and by BrdUrd labelling assays, indicating that a significantly higher percentage of p21+/- tumor cells were in S phase and mitosis than their p21+/+ and p21-/- counterparts. Moreover, cyclin D1-associated phosphorylation of retinoblastoma protein was significantly increased in p21+/- tumor lysates compared with p21+/+ and p21-/- lysates. These results are consistent with data indicating that reduced levels of p21 can facilitate cyclin/cdk complex formation while enhancing cdk activity. Thus, a reduction of p21 dosage may promote tumor progression in the presence of other oncogenic initiators. The dependence of p21 on prior oncogenic stimuli for its tumor-promoting activities suggests that it may behave as a tumor modifier gene rather than as a tumor suppressor gene.

Relative potencies of PAHs and PCBs based on the response of human cells

P450 reporter gene system (RGS) utilizes a human hepatoma cell line stably transfected with a plasmid containing firefly luciferase linked to human CYP1A1 promoter sequences. Luciferase expression in these cells is used to detect and quantify compounds that activate the Ah receptor (AhR) and induce CYP1A1. In this study, concentration-response curves were used to determine the relative potencies and calculate induction equivalency factors (IEFs) for non-ortho and mono-ortho coplanar PCBs and high-molecular weight PAHs. Relative potencies of PCBs were: 3,4,4',5-TetraCB (81)>3,3',4,4',5-PentaCB (126)>3,3',4,4'-TetraCB (77)≈2,3,4,4',5-PentaCB (114)>2,3',4,4',5-PentaCB (118)≈2',3,4,4',5-PentaCB (123)>3,3',4,4',5,5'-HexaCB (169). In addition, two other mono-ortho congeners, 2,3,3',4,4'-PentaCB (105) and 2,3,3',4,4',5-HexaCB (156), did not induce luciferase in these cells. Relative potencies of the PAHs were: benzo[k]fluoranthene>dibenz[a,h]anthracene>benzo[b]fluoranthene≈indeno[1,2,3-cd]pyrene>benzo[a]pyrene>chrysene≈benzo[a]anthracene>benzo[g,h,i]perylene. Relative potencies of PAHs are similar to those of PCBs.

Exon organization, coding sequence, physical mapping, and polymorphic intragenic markers for the human neuronal sodium channel gene SCN8A

The voltage-gated sodium channel SCN8A is associated with inherited neurological disorders in the mouse that include ataxia, dystonia, severe muscle weakness, and paralysis. We report the complete coding sequence and exon organization of the human SCN8A gene. The predicted 1980 amino acid residues are distributed among 28 exons, including two pairs of alternatively spliced exons. The SCN8A protein is evolutionarily conserved, with 98.5% amino acid sequence identity between human and mouse. Consensus sites for phosphorylation of serine/threonine and tyrosine residues are present in cyoplasmic loop domains. The polymorphic (CA)n microsatellite marker D12S2211, with PIC = 0.68, was isolated from intron 10C of SCN8A. Single nucleotide polymorphisms in intron 19 and exon 22 were also identified. We localized SCN8A to chromosome band 12q13.1 by physical mapping on a YAC contig. The cDNA clone CSC-1 was reported by others to be a cardiac-specific sodium channel, but sequence comparison demonstrates that it is derived from exon 24 of human SCN8A. The genetic information described here will be useful in evaluating SCN8A as a candidate gene for human neurological disease.