Emergence and scattering of multiple neurofibromatosis (NF1)-related sequences during hominoid evolution suggest a process of pericentromeric interchromosomal transposition

Type 1 neurofibromatosis (NF1) gene encodes for a member of the GTPase activating protein family and is considered to be a tumor suppressor gene. Its very high rate of de novo mutation in humans led us to study a specific feature of this gene: the presence of numerous NF1-related sequences. According to our results, the human genome contains at least 11 NF1-related sequences, nine of which are scattered near centromeric sequences of seven different chromosomes. These NF1-related sequences, whose extent is quite varied according to loci, are unprocessed copies of the NF1 gene, and bear numerous mutations. A phylogenetic analysis of the six largest sequences indicates that they are all derived from a common ancestor, which would have appeared 22-33 million years ago, and was subsequently duplicated several times during hominoid evolution. The most recent duplication and interchromosomal transposition occurred in the last million years suggesting that the process could still be ongoing. Intriguing similarities between the evolution of alpha- satellite DNA and NF1-related sequences suggest the involvement of a common genetic mechanism for the generation and pericentric spreading of these NF1 partial copies.      

Retrospective determination of HIV-1 status by a PCR method on paraffin wax embedded sections.

AIM--To develop a simple but reliable polymerase chain reaction (PCR) method to determine the HIV-1 status of patients on formalin fixed, paraffin wax embedded lymph node tissue. METHODS--Fifty lymph node specimens, 20 from HIV-1 seropositive and 30 from HIV-1 seronegative patients, were analysed. Lymph nodes with a variety of disease conditions were included in the study. Tissue sections were treated with a DNA extraction buffer containing proteinase K and the crude cell lysate was used in PCR analysis. Nested primers were used to amplify HIV-1 DNA sequences coding for gag, pol and env proteins. PCR products were demonstrated by polyacrylamide gel electrophoresis. Results were then compared with HIV-1 serology of the patients from whom the tissue was obtained. RESULTS--The PCR method yielded a specificity of 100%, a sensitivity of 95%, a positive predictive value of 100%, and a negative predictive value of 97% when compared with HIV-1 serology. The kappa statistic (0.958) showed an excellent agreement between the PCR method and serology. Furthermore, HIV-1 DNA was demonstrated in lymph node tissue from a serologically unconfirmed acquired immunodeficiency syndrome case necropsied in 1982. CONCLUSION--This PCR method is a simple and reliable means of retrospectively determining the HIV-1 status of patients using formalin fixed, paraffin wax embedded lymph node tissue.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Evaluation of merbarone (NSC 336628) in disseminated malignant melanoma

Merbarone, NSC 336628, is an investigational anticancer drug with activity against experimental animal tumors including melanoma. This paper presents results of a Phase II clinical study of merbarone in patients with biopsy proven stage IV malignant melanoma without prior chemotherapy and with no evidence of CNS involvement. Thirty-five patients with median age 58 (range 27–81), with performance status 0–2 were treated with merbarone 1000 mg/m²/day for five days by intravenous continuous infusion repeated every 3 weeks. All patients (21 males and 14 females) were evaluable for toxicity. Two patients were not evaluable for response having been removed from protocol treatment due to toxicity and received other treatment during the first course of chemotherapy. Among the evaluable patients there was one complete response in a supraclavicular lymph node lasting four months and one partial liver response lasting three months. The remaining thirty-one patients were non-reponders. Of these one had a stable disease lasting 21 months. The overall objective response rate was 6% (2/35) with a 95% confidence interval of 1%–19%. Twenty-six of the 35 patients have died. The estimated median survival of the entire group was 9 months with a 95% confidence interval of six to eleven months. Renal toxicity was dose-limiting and manifested as increasing serum creatinine (54% of patients), proteinuria (51%) and hematuria (9%). One patient experienced grade 4 creatinine increase, proteinuria and acute renal failure. Other toxicities included nausea (71%), vomiting (51%), malaise (23%), weakness (20%), alopecia (17%), diarrhea (17%), anorexia (14%), transaminase (SGOT, SGPT) increase (14%), constipation (14%), alkaline phosphatase or 5nucleotidase increase (9%), and fever (9%). Hematologictoxicity (granulocytopenia, leukopenia, and anemia) was generally mild and infrequent (29%, only one patient had grade 4 granulocytopenia). Overall 9 patients (26%) had at least one grade 3 toxicity. We conclude that merbarone at this dose and schedule has detectable but minimal activity in the treatment of metastatic malignant melanoma and given the significant renal toxicity this schedule does not merit further evaluation in this disease.     

Hydrolysis of the Prodrug, 2′, 3′, 5′ -Triacetyl-6-azauridine

Purpose. The purposes were to study the kinetics of hydrolysis of 2,3,5-triacetyl-6-azauridine ( 1 ) in aqueous solution (µ = 0.5) and to identify the main intermediates and products of the reaction. Methods. A stability indicating isocratic LC assay was used to study the rate of degradation of 1 A gradient LC assay was used to study the time courses of the degradants. The products of hydrolysis were isolated by preparative liquid chromatography and identified by ¹H-NMR and CI-MS. The pK_a value was obtained by potentiometric titration. Results. At 36.8°C, the pH-rate profile of 1 in water was adequately described by a four-term rate equation. The intermediates were identified as the primary and secondary di-acetates, and the primary and secondary mono-acetates. The final product was 6-azauridine. Conclusions. A simplified kinetic scheme could be used to describe the concentration-time profiles of 1, the intermediates and the final product.     

ANTIBIOTIC RESISTANCE PATTERN OF ISOLATES FROM WOUND AND SOFT TISSUE INFECTIONS

Two-hundred and eighty bacterial isolates from wound and soft tissue infections were studied for species identification and antibiotic resistance pattern. Amongst them 122 isolates were from community acquired infection and 158 were from nosocomial infections. The common community acquired pathogens were Staphylococcus aureus (67.8%) and Streptococcus pyogenes (10.7%), whereas Staphylococcus aureus (60.1%) and E. Coli (8.9%) were common in nosocomial infection. Only two anaerobes (Cl perfringens) were isolated. Penicillin resistance was found to be 87% and 92% for Staphylococccus aureus in community acquired and noscomial infections respectively. 85% of Proteus isolates were resistant to ampicillin. There was relatively lower level of resistance by all isolates to cefotaxime. Gentamicin showed higher rate of resistance than netilmicin and amikacin. Resistance of E. coli isolates to fluoroquinolones being 79% for norfloxacin, 81% for ciprofloxacin and 60% for ofloxacin. The study showed a higher resistance of methicillin resistant Staphylococcus aureus (MRSA) to other antibiotics. Amikacin and ofloxacin were the best recommended drugs for empirical therapy for all organisms, the susceptibility rate being 80.7% and 80.4%.KEY WORDS: Antibiotic resistance, Soft tissue infections, Wound infections     

5-Azacytidine. A new anticancer drug with effectiveness in acute myelogenous leukemia.

Clinical studies involving 5-azacytidine, a ring analogue of cytidine, began in Europe in 1967 and the United States in 1970, and we review available preclinical and clinical studies here. The drug possesses cytotoxic, antimicrobial, antineoplastic, abortive, and mutagenic activity in various biological systems. 5-Azacytidine is thought to exert its antineoplastic effect through interference with nucleic acid metabolism. The dose-limiting toxicities are nausea, vomiting, and leukopenia, while the incidence of thrombocytopenia is low. Hepatic toxicity ranges from abnormal findings in liver function tests to hepatic coma. Clinical results in solid tumors are not encouraging, but 5-azacytidine shows consistent antitumor activity in patients with acute myelogenous leukemia resistant to previous treatment. An overall response rate of 36%, with 20% complete remissions, was achieved in 200 previously treated patients with acute myelogenous leukemia. Further studies must define the role of 5-azacytidine alone and in combination for the first-line treatment of acute myelogenous leukemia.     

Pulmonary atresia with intact ventricular septum: range of morphology in a population-based study

OBJECTIVES: We describe the morphologic variability in pulmonary atresia with intact ventricular septum (PAIVS) within a population-based study. BACKGROUND: An uncommon disease, PAIVS shows considerable morphologic heterogeneity. Clinical reports, based mostly on small samples of patients, may not reflect the true spectrum of pathology of this condition. We have studied the entire range of morphology in a prospective population-based study of patients over a five-year period (1991 to 1995). METHODS; As part of the United Kingdom and Ireland Collaborative Study of PAIVS, all 18 pediatric cardiac centers were visited by a single investigator. Morphologic features of each case were determined by direct review of the echocardiograms and angiocardiograms, from surgical and autopsy reports, and by review of pathology specimens where available. RESULTS: Among 183 live-born infants, atresia was valvar (membranous) in 74.7% and muscular in 25.3%. Muscular obliteration of the apical trabecular cavity, and in some cases its infundibulum, resulted in "bipartite" right ventricle (RV) in 33.6%, and a "unipartite" chamber in 7.7%. The remaining 58.7% had "tripartite" morphology. Coronary arterial abnormalities were identified in 45.8%, including arterial stenoses, interruptions and ectasia in 7.6%. Ebstein's malformation coexisted in 18 patients. Median tricuspid valvar size and RV inlet Z-scores were -5.2 and -5.1, respectively. CONCLUSIONS: This study provides unique data on the diverse pathology of PAIVS in an unselected population. This will help determine if published reports reflect the true spectrum of pathology of the condition.