HLA antigens and malaria at San Lazaro Hospital Manila, Philippines

Human leucocyte antigens (HLA) were used as genetic markers in an attempt to determine possible host genetic susceptibility or resistance to malarial infections. HLA-A and B typing on lymphocytes from 68 confirmed P. falciparum and 77 P. vivax cases was compared with that found in 66 control subjects with no known history of malaria. A significant deviation was observed in the distribution of HLA-B27. This phenotype was absent in the P. falciparum group although found present in the P. vivax group (10%) and the control group (11%). Also, the combination of A9(w24) and B5 was significantly higher among the P. falciparum group than that found in the P. vivax and control groups. These findings require confirmation but do suggest the possibility of genetic susceptibility and that extensive genetic studies might be worth investigating.     

Microsatellite instability and novel mismatch repair gene mutations in northern Chinese population with Hereditary non‐polyposis colorectal cancer

OBJECTIVE: Hereditary non‐polyposis colorectal cancer (HNPCC) syndrome is the most common cause of hereditary colorectal cancer with an early age of onset. Microsatellite instability (MSI) and germline mutation in one of the DNA mismatch repair (MMR) genes are found in the majority of HNPCC families and provide an opportunity for genetic diagnosis and prophylactic screening. The MMR gene mutation spectrum may vary across different populations and be influenced by founder mutations that prevail in specific ethnic groups. China is a big and ancient nation with enormous genetic diversity, which is especially notable between the northern and southern Chinese populations. A MMR gene mutation database for the southern Chinese population based in Hong Kong has been previously established. This study compares the MMR gene mutation spectrum and the MSI of HNPCC between the northern and southern Chinese populations. METHODS: Twenty‐five HNPCC families from northern China were systematically analyzed. The MSI analysis was performed using five loci in the USA National Cancer Institute (NCI) panel (D2S123, D5S346, BAT‐25, BAT‐26 and BAT‐40) by PCR from the tumor and normal tissue. MSH2, MSH6 and MLH1 were performed using immunohistochemical staining. Two founder mutations of MSH2 and MLH1 were examined by PCR base analyses using primers flanking the two deletion sites (c.1452_1455delAATG in MSH2 and 1.8 kb deletion involving exon 11 of MLH1) . RESULTS: Of the 25 families collected, 19 met Bethesda guideline (BG) 1 and six met BG3. Twenty‐two (15.7%) were extra‐colonic cancers with gastric cancer (in seven patients) being the most common cancer type. Of the 25 tumors analyzed, 21 (84%) were high level microsatellite instability (MSI‐H) and four (16%) were microsatellite stable (MSS). Eighteen (86%) of the 21 MSI‐H tumors showed loss of either the MLH1 or the MSH2 protein. Three MSI‐H tumors and all four MSS tumors showed no loss of expression of the three MMR proteins. Out of the 21 patients with MSI‐H tumors, 12 (57%) showed pathogenic germline mutations in either MLH1 (n = 8) or MSH2 (n = 4). Overall, three novel mutations (in patients H22, H17 and H29) have been identified. One of them, c.503_4insA, caused a frameshift mutation in the MLH1 gene. The other two were found in the MSH2 gene, including a frameshift (c.899_890insAT) and a splice junction (IVS7‐1G→A, SA of Exon 8) mutation. CONCLUSIONS: The results suggest a distinctly different mutation spectrum of MMR genes between northern and southern Chinese populations and call for a systematic, nationwide study to facilitate the design of a MMR gene mutation detection strategy tailored for individual populations in China.     

Survival and relapse rate of tuberculosis patients who successfully completed treatment in Vietnam.

SETTING: Reported tuberculosis (TB) cure rates are high in Vietnam with the 8-month short-course chemotherapy regimen. However, long-term treatment outcomes are unknown. OBJECTIVE: To assess survival and relapse rates among patients successfully treated for new smear-positive pulmonary tuberculosis (PTB). METHODS: A cohort of patients treated in 32 randomly selected districts in northern Vietnam were followed up 12-24 months after reported cure or treatment success for survival and bacteriologically confirmed relapse. Measurements included sputum smear examination, culture and interview for recent treatment history. RESULTS: Of 304 patients included in the study, no information was available for 31 (10%) and 19 (6%) had died. Bacteriology results were available for 244 (80%). The median interval between treatment completion and follow-up was 19 months. Relapse was recorded in 21/244 (8.6%, 95%CI 5.4-13), including 9 (4%) with positive sputum smears, 3 (1%) with negative smears but positive culture and 9 (4%) who had started TB retreatment. Four of 12 culture-positive relapse cases (33%) had multidrug-resistant strains. If the definition of relapse was extended to include death, reportedly due to TB, the relapse proportion was 26/263 (9.9%, 95%CI 6.6-14). CONCLUSION: A substantial proportion of patients (15%) had died or relapsed after being successfully treated for TB in northern Vietnam.     

Population-based chest X-ray screening for pulmonary tuberculosis in people living with HIV/AIDS, An Giang, Vietnam.

SETTING: Human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS) program, An Giang Province, Vietnam. OBJECTIVE: To evaluate the coverage and yield of a chest radiography (CXR) screening program for tuberculosis (TB) among people living with HIV/AIDS (PLHA), risk factors for a TB CXR, inter-rater reliability of CXR readings and direct costs. DESIGN: Retrospective review of routine public health program records and CXRs. RESULTS: An increasing proportion of PLHAs received a screening CXR each year of the program (range 21% in 2001 to 61% in 2004, P<0.001). Of 876 screening CXRs performed, 191 (22%) were classified as suspicious for active TB ('TB CXR'). Compared to PLHAs with a CXR not suspicious for active TB, PLHAs with a TB CXR were more likely to be aged between 24 and 64 years, male and previously treated for TB (P<0.01 for each comparison). Agreement between the expert and local program CXR readings was 81% (kappa 0.50). Direct costs were approximately US$40 per TB suspect identified. Among TB suspects, <10% were followed up with sputum smear examination and enrolled for treatment. CONCLUSION: In An Giang Province, a large proportion of PLHAs are screened for TB annually, and one in five persons screened is classified as a TB suspect based on CXR. Annual CXRs may be a high-yield, inexpensive method for TB screening in PLHAs, but the follow-up of TB suspects to confirm diagnosis and initiate treatment is crucial.     

Hemostatic plug formation in normal and von Willebrand pigs: the effect of the administration of cryoprecipitate and a monoclonal antibody to Willebrand factor

Hemostatic plug (HP) formation was investigated in the ear bleeding time incision in normal and von Willebrand pigs. HP volume was calculated by integrating the areas of serial sections. In normal pigs (n = 11), platelets immediately formed a layer on the surface of the cut channel. Platelet aggregates formed at the ends of transected vessels and gradually enlarged. Finally, all transected vessels were occluded by HP and bleeding stopped. In contrast, large HPs were formed in the incision in von Willebrand's disease (vWD) pigs (n = 4); these HPs did not cover the ends of the transected vessels, which continued to bleed, allowing the formation of large hemostatically ineffective platelet aggregates in the incision. Canals traversed these HPs, and bleeding from the open vessels may have continued through them. After infusion of cryoprecipitate into a vWD pig, the bleeding time shortened, and the morphological findings of the HPs were similar to those of normal pigs. In normal pigs (n = 3) infused with an anti- Willebrand factor monoclonal antibody, which prolonged the bleeding time, a large HP formed in the incision, similar to that observed in the vWD pig. The volume of the normal and vWD HPs increased with time. These in vivo findings suggest that Willebrand factor is involved in the localization of the HP to the damaged vessel and may also play a role in platelet-platelet interaction. A computerized morphometric technique was used for measuring the volume of the hemostatic plugs and the distance of sequential points on the perimeter of the HP from the center of selected bleeding vessels.     

Expression of hyaluronidase by tumor cells induces angiogenesis in vivo.

Hyaluronic acid is a proteoglycan present in the extracellular matrix and is important for the maintenance of tissue architecture. Depolymerization of hyaluronic acid may facilitate tumor invasion. In addition, oligosaccharides of hyaluronic acid have been reported to induce angiogenesis. We report here that a hyaluronidase similar to the one on human sperm is expressed by metastatic human melanoma, colon carcinoma, and glioblastoma cell lines and by tumor biopsies from patients with colorectal carcinomas, but not by tissues from normal colon. Moreover, angiogenesis is induced by hyaluronidase+ tumor cells but not hyaluronidase- tumor cells and can be blocked by an inhibitor of hyaluronidase. Tumor cells thus use hyaluronidase as one of the "molecular saboteurs" to depolymerize hyaluronic acid to facilitate invasion. As a consequence, breakdown products of hyaluronic acid can further promote tumor establishment by inducing angiogenesis. Hyaluronidase on tumor cells may provide a target for anti-neoplastic drugs.