Sperm output of healthy men in Australia: magnitude of bias due to self- selected volunteers

Controversial claims, based on a meta-analysis aggregating 61 heterogeneous observational studies, have been made that human sperm output has decreased by 50% over the last six decades and that this trend may be due to global pollution. If true, such effects should be evident in all areas of the globe; however, longitudinal studies within single centres in Europe and America have produced conflicting results and there are no reports from the southern hemisphere. We therefore reviewed semen analyses obtained from 1980-1995 from 689 healthy men volunteering for screening either as potential sperm donors for a donor insemination programme (n = 509) or to participate in five male contraception research studies (studies no. 1-5, n = 180). All were recruited through the Andrology Unit of the Royal Prince Alfred Hospital, Sydney, by the same doctors using standard methods of recruiting, screening and laboratory examination throughout the period 1980-1995. Recruitment was by advertising without regard to marital or fertility status except in two contraceptive efficacy studies (no. 1 and no. 3) where participants had to be in a stable relationship requiring contraception. Analysing the first semen sample individually or when grouped by year of ejaculation, there was no significant difference in sperm concentration over time or between years or according to year of birth. During the second half of this period, 180 consecutive volunteers were recruited by the same doctors and staff for five male contraception studies. The median sperm concentration for studies no. 1 (103 x 10(6) ml) and no. 2 (142 x 10(6) ml) were significantly (P < 0.05) higher than for studies no. 3-5 (84, 67 and 63 x 10(6) ml, respectively) and for potential sperm donors (median 69 x 10(6) ml). The inconsistency of these estimates illustrates the magnitude of bias (up to 100%) in sperm output that may occur in recruiting groups of self-referred volunteers within a single centre. This highlights the invalidity of extrapolating similar findings on sperm output of self-selected volunteers to the general male community or in using such study groups to characterize sperm output in supposedly 'normal' men.      

Absence of DAZ gene mutations in cases of non-obstructed azoospermia

Sequenced-tagged site (STS) analysis of the Y chromosome long arm (Yq) of azoospermic males has identified a minimum common deleted region of several hundred kilobases in approximately 13% of cases. A candidate azoospermia gene, DAZ (deleted in azoospermia), has been isolated from this region. DAZ has also been shown to be absent in severely oligozoospermic males albeit at a much lower frequency. These data, although highly suggestive, do not constitute formal proof that DAZ actually plays a role in azoospermia, as no small intragenic deletions, rearrangements or point mutations in the gene have been found. In this study we report the screening of DNA from 168 azoospermic/oligospermic males for the presence of the DAZ gene. Deletions involving DAZ were detected in five out of 43 (11.6%) azoospermic males whereas none were found in the remaining 125 oligospermic patients. We present the genomic structure of the 5' end of the DAZ gene together with its sequence analysis in 30 non-obstructed azoospermic males. No mutations in DAZ were found in any of the patients sequenced. These data provide no formal proof that DAZ is AZF. Thus the possibility is still valid that another gene(s) mapping to the deletion interval may be responsible for, or contribute to, the observed phenotypes. Alternatively, if DAZ is AZF, they suggest that the most frequent cause of gene inactivation is via large deletions possibly mobilized by Y chromosome repetitive sequences.      

How I do it: Head and neck and plastic surgery: Surgical management of the head and neck cancer patient following concomitant multimodality therapy

The simultaneous use of chemotherapy and radiotherapy (concomitant therapy) has exceptional promise in the treatment of head and neck cancer. In this limited review, seven head and neck cancer patients who underwent prior concomitant therapy and subsequent surgery developed wound-healing complications that were delayed (22-day average) in onset. Paranasal sinus and base of skull operations had less significant wound morbidity than those cases requiring simultaneous transgression of the neck and upper aerodigestive tract. The use of arterialized flaps did not in itself prevent wound breakdown. The formation of controlled fistulae, delay of reconstruction, and avoidance of simultaneous neck and upper aerodigestive tract entry are important considerations in avoiding wound-healing complications after concomitant therapy. In this select group of patients, surgery should be approached with extreme caution and conservatism.     

Duodenitis: endoscopic-radiologic correlation in 272 patients

Potential radiologic findings of duodenitis were investigated in 272 patients, 157 with endoscopically diagnosed duodenitis and 115 endoscopically normal controls. The study assessed the value of four signs: folds more than 4 mm thick, mucosal nodules, bulbar deformity, and erosions. The most sensitive signs were thickened folds (72.0%) and nodularity (48.4%), while demonstration of erosions was the least sensitive (10.8%). Overall sensitivity (77.7%) approximated that for the radiologic diagnosis of peptic ulcer or esophagitis. Radiologic specificity (76.5%) was in the same range.     

Molecular basis of reduced or absent expression of decay-accelerating factor in Cromer blood group phenotypes

The human erythrocyte blood group system Cromer consists of high- incidence and low-incidence antigens that reside on decay-accelerating factor (DAF; CD55), a glycosyl-phosphatidylinositol-anchored membrane protein that regulates complement activation on cell surfaces. In the Cromer phenotypes Dr(a-) and Inab there is reduced or absent expression of DAF, respectively. This study investigated the molecular basis of the reduced DAF expression by polymerase chain reaction amplification of genomic DNA and RNA/cDNA obtained from Epstein-Barr virus- transformed lymphoblastoid cell lines. Sequence analysis of the Inab propositus showed a single nucleotide substitution in exon 2 of the DAF gene and at the corresponding position in the cDNA, G314-->A resulting in Trp53-->Stop. This truncation near the amino terminus explains the complete absence of surface DAF in the Inab phenotype. A similar analysis was performed for two Dr(a-) individuals, including KZ, who was previously reported to be Inab phenotype but is now shown by immunochemical and serologic methods to be Dr(a-) phenotype. A single nucleotide change was found in exon 5 of the DAF gene, C649-->T resulting in Ser165-->Leu, which we had previously shown to lead to loss of the Dra epitope. However, two species of cDNA were found, one encoding full-length DAF with the single amino acid change and the more abundant species having a 44-nucleotide deletion. The 44 nucleotide deletion includes the single polymorphic site, which creates a cryptic branch point in the Dr(a-) allele that leads to use of a downstream cryptic acceptor splice site. This shifts the reading frame and leads to a premature stop codon that precludes membrane anchoring. Thus, the single point mutation in the Dr(a-) phenotype results in a novel use of alternative splicing and provides a molecular explanation for both the antigenicity and the reduced DAF expression seen in this phenotype.     

Ranitidine bismuth citrate plus clarithromycin is effective for healing duodenal ulcers, eradicating H. pylori and reducing ulcer recurrence. RBC H. pylori Study Group [see comments]

AIM: To compare the efficacy of the coadministration of ranitidine bismuth citrate plus the antibiotic clarithromycin, with ranitidine bismuth citrate alone or clarithromycin alone for the healing of duodenal ulcers, eradication of H. pylori and the reduction of ulcer recurrence. METHODS: This two-phase, randomized, double-blind, placebo- controlled, multicentre study consisted of a 4-week treatment phase followed by a 24-week post-treatment observation phase. Patients with an active duodenal ulcer were treated with either ranitidine bismuth citrate 400 mg b.d. for 4 weeks plus clarithromycin 500 mg t.d.s. for the first 2 weeks; ranitidine bismuth citrate 400 mg b.d. for 4 weeks plus placebo t.d.s. for first 2 weeks; placebo b.d. for 4 weeks plus clarithromycin 500 mg t.d.s. for the first 2 weeks; or placebo b.d. for 4 weeks plus placebo t.d.s. for the first 2 weeks. RESULTS: Ulcer healing rates after 4 weeks of treatment were highest with ranitidine bismuth citrate plus clarithromycin (82%) followed by ranitidine bismuth citrate alone (74%; P = 0.373), clarithromycin alone (73%; P = 0.33) and placebo (52%; P = 0.007). Ranitidine bismuth citrate plus clarithromycin provided significantly better ulcer symptom relief compared with clarithromycin alone or placebo (P < 0.05). The coadministration of ranitidine bismuth citrate plus clarithromycin resulted in significantly higher H. pylori eradication rates 4 weeks post-treatment (82%) than did treatment with either ranitidine bismuth citrate alone (0%; P < 0.001), clarithromycin alone (36%; P = 0.008) or placebo (0%; P < 0.001). Ulcer recurrence rates 24 weeks post-treatment were lower following treatment with ranitidine bismuth citrate plus clarithromycin (21%) compared with ranitidine bismuth citrate alone (86%; P < 0.001), clarithromycin alone (40%; P = 0.062) or placebo (88%; P = 0.006). All treatments were well tolerated. CONCLUSIONS: The coadministration of ranitidine bismuth citrate plus clarithromycin is a simple, well-tolerated and effective treatment for active H. pylori- associated duodenal ulcer disease. This treatment regimen effectively heals duodenal ulcers, provides effective symptom relief, eradicates H. pylori infection and reduces the rate of ulcer recurrence. The eradication of H. pylori infection in patients with recently healed duodenal ulcers is associated with a significant reduction in the rate of ulcer recurrence.     

Purification and characterization of the human neutrophil NADH- cytochrome b5 reductase

NADH-cytochrome b5 reductase is the predominant NADH-diaphorase found in the human neutrophil (Blood 62:152, 1983). Although this reductase segregates with the light membranes of nitrogen-cavitated neutrophils separated on Percoll gradients (which include the plasma membrane markers alkaline phosphatase and NADPH-oxidase), it is approximately 95% excluded from plasma membrane-enriched phagocytic vacuoles. The reductase constitutes approximately 5% of the light membrane fraction FAD-flavoprotein (14.8 +/- 5.5 pmol/mg protein) and was found in equimolar concentration with a high potential b cytochrome also present in this light membrane fraction and tentatively identified as cytochrome b5. Isolation of the reductase from human neutrophils was accomplished by Triton X-114 solubilization of the light Percoll gradient membranes, followed by temperature-dependent phase separation and then affinity chromatography on AMP-Sepharose. The active preparation contained 1.3 mol FAD/mol protein, migrated on sodium dodecyl sulfate-polyacrylamide gels as a single band corresponding to an apparent mol wt of 45,000 daltons, exhibited a pl of 5.7 on chromatofocusing and was obtained in greater than 70% yield, with an overall purification of almost 900-fold. The purified enzyme was characterized by a high specificity for NADH as electron donor (Km = 6.4 mumol/L v Km greater than 1.6 mmol/L for NADPH) and exhibited a maximal turnover of ca. 30,000 min-1 at 22 degrees C with either ferricyanide or cytochrome b5 (Km = 10 nmol/L) as electron acceptor. Although the physical characterization and biochemical properties described here demonstrate that this neutrophil NADH b5 reductase is similar to the corresponding liver and erythrocyte enzymes, its unique function in the neutrophil has yet to be determined.