Scrotal skin ulcer in a patient with a previous tonsillectomy because of natural killer cell lymphoma

The CD56+ lymphomas are a recently characterized high-grade malignancy of putative natural killer cell origin. They are mostly localized to the nasal areas but show a propensity to spread to or recur in the skin. We describe a unique case of CD56+ natural killer lymphoma that recurred in scrotal skin in a patient 8 years after an initial limited resection. Although this case was unusual in showing a prolonged period of apparent remission, it illustrated a characteristic clinicopathologic behavior of this rare tumor.     

Src can regulate carboxy terminal interactions with AFAP-110, which influence self-association, cell localization and actin filament integrity

The SH2 and SH3 binding partner AFAP-110 is a tyrosine phosphorylated substrate of Src. AFAP-110 has been hypothesized to link Src to actin filaments, which may contribute to the effects of Src upon actin filament integrity. However, it has been unclear what effect activated Src (Src527F) has upon AFAP-110 structure or function and whether AFAP-110 plays a role in actin filament integrity. We report here that the carboxy terminal 127 amino acids of AFAP-110 are comprised of an alpha-helical region that contains a leucine zipper motif. This indicated the potential of AFAP-110 to self-associate. Expression of the carboxy terminus as a fusion protein (GST-cterm) will permit affinity absorption of cellular AFAP-110. The integrity of the alpha-helical leucine zipper motif in GST-cterm is required for affinity absorption, but binding is not due to a classical leucine zipper interaction. Co-expression of Src527F, unlike cSrc, will abrogate affinity absorption of AFAP-110 with GST-cterm. These data indicate that Src527F has affected a change in the carboxy terminal structure that renders AFAP-110 unavailable for affinity absorption. Superose chromatography demonstrate that AFAP-110 will fractionate as a monomer or multimer, indicating AFAP-110 can be detected in a self-associated form in cell lysates. Co-expression of Src527F resulted in AFAP-110 fractionating with a molecular weight that predicts only a multimeric population. Deletional mutagenesis also indicate a biological role for the carboxy terminus in cellular localization and actin filament integrity. Deletion of the entire carboxy terminal alpha-helix (84 amino acids) will not permit AFAP-110 to efficiently colocalize with actin filaments or the cell membrane. Deletion of only the leucine zipper region of the carboxy terminal alpha-helix (44 amino acids) from AFAP-110 (AFAPAdeltazip) demonstrate that both AFAPdeltalzip and actin filaments are repositioned into rosette-like structures, similar to the effects of Src527F, while co-expression of AFAP-110 with cSrc will not affect actin filaments. These data indicate that AFAP-110 can play an important role in modulating actin filament integrity through carboxy terminal interactions that can be affected by Src527F.     

Segregation distortion in myotonic dystrophy

Myotonic dystrophy (DM) is an autosomal dominant disease which, in the typical pedigree, shows a three generation anticipation cascade. This results in infertility and congenital myotonic dystrophy (CDM) with the disappearance of DM in that pedigree. The concept of segregation distortion, where there is preferential transmission of the larger allele at the DM locus, has been put forward to explain partially the maintenance of DM in the population. In a survey of DM in Northern Ireland, 59 pedigrees were ascertained. Sibships where the status of all the members had been identified were examined to determine the transmission of the DM expansion from affected parents to their offspring. Where the transmitting parent was male, 58.3% of the offspring were affected, and in the case of a female transmitting parent, 68.7% were affected. Studies on meiotic drive in DM have shown increased transmission of the larger allele at the DM locus in non-DM heterozygotes for CTGn. This study provides further evidence that the DM expansion tends to be transmitted preferentially.     

Low prevalence of human papillomavirus in a geographic region with a high incidence of head and neck cancer

BACKGROUND: The main purpose of this study was to determine the prevalence of human papillomavirus (HPV) infection in patients with head and neck carcinomas from Brazil. MATERIALS AND METHODS: Forty-five patients with head and neck squamous cell carcinoma were included in the study, from 1995 to 1996. Forty-two were male and 3 female, with age ranging from 32 to 82 years (median 61). Five patients (11%) did not have previous history of use of tobacco and 38 (90.5%) were heavy smokers. Tumor sites were pyriform sinus, 10; tongue, 11 (oral, 6; base, 5); larynx, 7; floor of mouth, 3; tonsil, 6; retromolar area, 3; inferior gingiva 2; buccal mucosa, 2; and maxillary sinus in 1 patient. Twenty-five were stage IV, 17 stage III, and 3 stage II. RESULTS: The presence of HPV DNA was detected in 5 of 45 patients (11%), all of them with HPV 16. Two patients had HPV DNA in normal mucosa and tumor tissue, 1 patient had HPV DNA only in the normal mucosa and tumor tissue, 1 patient had HPV DNA only in the normal mucosa, and 2 patients were positive for HPV DNA in tumor tissue. Four patients were male and 1 was female; 2 patients were nonsmokers. Three patients had tonsil carcinoma, 1 patient had a tongue carcinoma, and 1 patient had a pyriform sinus cancer. CONCLUSIONS: The role of chemical carcinogens seems to be more important in the genesis of head and neck cancer than is HPV infection. The presence of HPV DNA in 5 of 45 patients stimulates further investigation to determine the role of HPV as a risk factor for head and neck carcinoma.     

Campylobacter enteritis in Johannesburg

In order to establish a reasonable protocol for a diagnostic laboratory we conducted a survey during which we confined the routine culture of stool samples for Campylobacter fetus to two groups--all infants under 2 years of age, and older children and adults with obviously diarrhoeic stools. Camp. fetus was isolated from 100 of 2323 stool specimens (4,3%). This is within the 3 - 8% isolation rates previously reported from surveys in which all specimens were cultured. Camp. fetus isolates represented 16,9% of all bacterial pathogens isolated, and Black infants showed a significantly greater isolation rate than White infants. We feel that culture for Camp. fetus is an essential part of any routine bacteriological investigation of diarrhoea. A partially selective culture policy for Camp. fetus will result in a recovery rate at least equal to that of Salmonella and enteropathogenic Escherichia coli.     

Specific changes in the in vitro production of prostanoids by the ovine cervix at parturition

A method of tissue superfusion has been used to measure in vitro prostanoid production by the ovine cervix during late pregnancy and at parturition. In late pregnancy (105-135 days of gestation) cervical tissue produced relatively large amounts of prostaglandin E (PGE); in comparison, the production rates of prostaglandin F (PGF), 13, 14-dihydro-15-oxo-prostaglandin F (PGFM) and 6-oxo-prostaglandin F1 alpha were generally low. Thromboxane B2 (TXB2) production was minimal and often unmeasurable. There were significant increases in the production rates of PGE and 6-oxo-PGF1 alpha by cervical tissue taken immediately after delivery, when compared to late pregnancy. Mean production rates of PGE increased from 19.8 +/- 4.1 to 43.8 +/- 7.4 ng/g. dry wt./min; 6-oxo-PGF1 alpha production rates increased more than three-fold from 10.0 +/- 2.7 to 34.6 +/- 9.8 ng/g. dry wt./min (means +/- S.E.M.). There were no significant differences in the rates of production of PGF, PGFM and TXB2 by the two groups.     

The direct measurement of embryogenic volume and nucleo-cytoplasmic ratio during mouse pre-implantation development

Stringent selection mechanisms, in both internal and external fertilisation systems, reject all but a significant minority of the spermatozoa released at ejaculation. Sperm competition theory provides circumstantial evidence that the selection process involves mechanisms by which the quality of the fertilising spermatozoon is controlled, thereby ensuring that females and their offspring receive high quality genetic material. In this review we examine some of these selection processes to see whether they could be exploited for the improvement of laboratory tests of sperm quality. Such tests are not only required for clinical and agricultural purposes, but are increasingly needed in fields such as reproductive and environmental toxicology where the species requirement is much broader. Despite many years of research, sperm quality assessment methods continue to provide imprecise data about fertility; here we suggest that this may be a consequence of using tests that focus on the spermatozoa that would normally be unable to fertilise under natural conditions. To achieve fertilisation a spermatozoon must be capable of responding appropriately to external signalling stimuli; those involving protein kinase-regulated flagellar function seem especially influential in governing effects ranging from non-Mendelian inheritance in mammals to sperm chemotaxis in sea urchins. Examination of the elicited responses reveals considerable heterogeneity in all species. Here we propose that this level of heterogeneity is meaningful both in terms of understanding how spermatozoa from some individuals possess fertility advantages over spermatozoa from their rivals in sperm competition, and in that the heterogeneity should be exploitable in the development of more accurate laboratory tests.