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Biomedical subjects

R Ishak

Publications and source records attributed to R Ishak.

At least 19 recordsLinked to original sources
PubMed2006

Molecular evidence for infection by HTLV-2 among individuals with negative serological screening tests for HTLV antibodies.

Previous serological studies on the Arara do Laranjal Indian group revealed extensive HTLV-2 infections. A collection of 97 new samples from the Arara were found repeatedly negative using three different commercial enzyme immunoassays. Eight samples that exhibited optical density readings close to the cut-off value were re-evaluated using Western blot (GeneLab 2.4, Singapore) assay. One sample was found to be non-reactive, five exhibited indeterminate patterns, one was classified as HTLV, and one was confirmed as HTLV-2. Peripheral blood mononuclear cell DNA of the eight samples were subjected to nested PCR and restriction fragment length polymorphism (RFLP) analysis of the pX and env regions, and nucleotide sequencing of the 5'-LTR region. All produced amplification products of pX, but env could be amplified in only one sample with the commonly used primers. RFLP analysis of the pX region using TaqI confirmed HTLV-2 infection. Nucleotide sequencing of the 5'-LTR region was performed in three samples (HTLV-2, HTLV and indeterminate based on Western blot pattern). Phylogenetic analysis of a 449-nt fragment using the Neighbour-Joining method clearly demonstrated that the three samples clustered within the HTLV-2c molecular subtype. The present study confirms the wide dissemination of the HTLV-2c subtype among linguistically and culturally distinct Amazonian Indian groups, and emphasizes the unique occurrence of infection by this subtype in Brazil. Moreover, it emphasizes the limitation of employing the present serological screening assays in blood banks, epidemiological studies, and the importance of molecular assays in the confirmatory procedures for the primary detection of HTLV-2 infections.

Brazil↗
PubMed2006

Identification of human T-cell lymphotropic virus infection in a semi-isolated Afro-Brazilian quilombo located in the Marajó Island (Pará, Brazil).

Antibodies to human T-cell lymphotropic virus-1 and 2 (HTLV-1 and 2) were tested in 259 inhabitants (98 males and 161 females) of four villages of the Marajó Island (Pará, Brazil) using enzyme immunoassays (ELISA and Western blot). Types and subtypes of HTLV were determined by nested polymerase chain reaction (PCR) targeting the pX, env and 5 LTR regions. HTLV-1 infection was detected in Santana do Arari (2.06%) and Ponta de Pedras (1%). HTLV-2 was detected only in Santana do Arari (1.06%). Sequencing of the 5 LTR region of HTLV-1 and the phylogenetic analysis identified the virus as a member of the Cosmopolitan Group, subgroup Transcontinental. Santana do Arari is an Afro-Brazilian community and the current results represent the first report of HTLV-1 infection in a mocambo located in the Brazilian Amazon region.

Adolescent↗
PubMed2005

Molecular characterization of human T-cell lymphotropic virus coinfecting human immunodeficiency virus 1 infected patients in the Amazon region of Brazil.

The present work evaluated the epidemiology of human immunodeficiency virus 1/human T-cell lymphotropic virus (HIV-1/HTLV) coinfection in patients living in Belém (state of Pará) and Macapá (state of Amapá), two cities located in the Amazon region of Brazil. A total of 169 blood samples were collected. The sera were tested by enzyme-linked immunosorbent assay to determine the presence of antibodies anti-HTLV-1/2. Confirmation of infection and discrimination of HTLV types and subtypes was performed using a nested polymerase chain reaction targeting the pX and 5' LTR regions, followed by restriction fragment length polymorphism and sequencing analysis. The presence of anti-HTLV1/2 was detected in six patients from Belém. The amplification of the pX region followed by RFLP analysis, demonstrated the presence of HTLV-1 and HTLV-2 infections among two and four patients, respectively. Sequencing HTLV-1 5' LTR indicated that the virus is a member of the Cosmopolitan Group, Transcontinental subgroup. HTLV-2 strains isolated revealed a molecular profile of subtype HTLV-2c. These results are a reflex of the epidemiological features of HIV-1/HTLV-1/2 coinfection in the North region of Brazil, which is distinct from other Brazilian regions, as reported by previous studies.

Brazil↗
PubMed2005

Characterization of mannose-binding lectin gene polymorphism among human T-cell lymphotropic virus 1 and 2-infected asymptomatic subjects.

The present study investigated the association between mannose-binding lectin (MBL) gene polymorphism and the susceptibility to human T-cell lymphotropic virus (HTLV) infection in a group of 83 HTLV-infected asymptomatic subjects (62 HTLV-1 and 21 HTLV-2) and 99 healthy controls. Detection of MBL*A, MBL*B, and MBL*C was performed by amplifying a fragment of 349 bp (exon 1) and submitting the product to restriction fragment length polymorphism analysis with BanI and MboII endonucleases. Allele MBL*D was investigated by sequence-specific primer-polymerase chain reaction. The frequency of MBL*A, MBL*B, and MBL*D was 63%, 22%, and 15% among seropositive subjects and 70%, 14%, and 16% among healthy controls, respectively. Genotype differences were statistically significant (chi2 = 11.57; p = 0.04); the presence of genotype BB was 9.6% among HTLV-infected patients compared with 1% among controls (chi2 = 7.151; p = 0.019). A significant difference of the genotype frequencies between HTLV-1 and HTLV-2 infections was observed, but this result could be attributed to the number of investigated HTLV-1-infected subjects. The odds ratio to the presence of BB genotype was 10.453 (1.279 < or = IC95% < or = 85.40; p = 0.019). Results reveal a strong association between MBL polymorphism and HTLV infection. Presence of genotype BB may be associated with the susceptibility to HTLV, but further studies, with a larger number of individuals, will be necessary. MBL polymorphism could possibly have an impact on diseases associated with HTLV infection.

Deltaretrovirus Infections↗
PubMed2001

Selective nonoperative management in 1,856 patients with abdominal gunshot wounds: should routine laparotomy still be the standard of care?

OBJECTIVE: To evaluate the safety of a policy of selective nonoperative management (SNOM) in patients with abdominal gunshot wounds. SUMMARY BACKGROUND DATA: Selective nonoperative management is practiced extensively in stab wounds and blunt abdominal trauma, but routine laparotomy is still the standard of care in abdominal gunshot wounds. METHODS: The authors reviewed the medical records of 1,856 patients with abdominal gunshot wounds (1,405 anterior, 451 posterior) admitted during an 8-year period in a busy academic level 1 trauma center and managed by SNOM. According to this policy, patients who did not have peritonitis, were hemodynamically stable, and had a reliable clinical examination were observed. RESULTS: Initially, 792 (42%) patients (34% of patients with anterior and 68% with posterior abdominal gunshot wounds) were selected for nonoperative management. During observation 80 (4%) patients developed symptoms and required a delayed laparotomy, which revealed organ injuries requiring repair in 57. Five (0.3%) patients suffered complications potentially related to the delay in laparotomy, which were managed successfully. Seven hundred twelve (38%) patients were successfully managed without an operation. The rate of unnecessary laparotomy was 14% among operated patients (or 9% among all patients). If patients were managed by routine laparotomy, the unnecessary laparotomy rate would have been 47% (39% for anterior and 74% for posterior abdominal gunshot wounds). Compared with patients with unnecessary laparotomy, patients managed without surgery had significantly shorter hospital stays and lower hospital charges. By maintaining a policy of SNOM instead of routine laparotomy, a total of 3,560 hospital days and $9,555,752 in hospital charges were saved over the period of the study. CONCLUSION: Selective nonoperative management is a safe method for managing patients with abdominal gunshot wounds in a level 1 trauma center with an in-house trauma team. It reduces significantly the rate of unnecessary laparotomy and hospital charges.

Abdominal Injuries↗
PubMed2000

Isolation, cloning, and complete nucleotide sequence of a phenotypically distinct Brazilian isolate of human T-lymphotropic virus type II (HTLV-II).

Analysis of human T-lymphotropic virus type II (HTLV-II) isolates from North America and Europe have demonstrated the existence of two molecular subtypes of the virus, HTLV-IIa and HTLV-IIb. Recently, studies on HTLV-II infections in Brazil have revealed isolates that are related phylogenetically to the HTLV-IIa subtype but have a HTLV-IIb phenotype with respect to the transactivating protein, tax. To more clearly define this relationship, HTLV-II was isolated from peripheral blood of an IVDA from Sao Paulo, Brazil (SP-WV), and the complete provirus was cloned and sequenced. Comparison of HTLV-II(SP-WV) nucleotide sequences to other available complete HTLV-II proviral sequences revealed that HTLV-II(SP-WV) is most closely related to HTLV-II(Mo), the prototypic HTLV-IIa subtype sequence. Phylogenetic analysis of LTR, env, and tax regions unequivocally demonstrated that HTLV-II(SP-WV) and all other Brazilian sequences examined are members of the IIa subtype. The predicted amino acid sequences of the major coding regions of HTLV-II(SP-WV) are also most closely related to HTLV-II(Mo), with the important exception of tax. The tax protein encoded by HTLV-II(SP-WV) is 96-99% identical to the tax of IIb isolates and is similar in that it has an additional 25 amino acids at the carboxy-terminus compared to the HTLV-II(Mo) tax with which it shares 91% identity. Analysis of tax stop codon usage of a number of HTLV-IIa isolates from North American, Europe, and Brazil demonstrated that isolates from the last region appear to be unique in their extended tax phenotype. It could be demonstrated that the extended tax proteins in the HTLV-IIb and Brazilian isolates had equivalent ability to transactivate the viral LTR, and studies with deletion mutants indicated that the extended C-terminus is not essential for transactivation. In contrast, the HTLV-IIa tax was found to have a greatly diminished ability to transactivate the viral LTR, which appeared to be a consequence of reduced expression of the protein. The studies show that although the Brazilian strains do not represent an entirely new subtype based on nucleotide sequence analysis they are a phenotypically unique molecular variant within the HTLV-IIa subtype.

Brazil↗
PubMed1997

Detection of carrier status of hemophilia B using DNA markers.

Hemophilia B is an X-linked recessive disorder of the hemostasis involving a defective clotting factor IX. Amplification of the regions containing restriction fragment length polymorphisms (RFLP) can be achieved by the use of polymerase chain reaction (PCR). This paper describes the analysis of 2 RFLPs involving the Dde1 and Taq1 restriction sites within the factor IX gene in a family with hemophilia B. Digestion of the PCR products with Taq1 revealed a 163bp fragment in all the family members. This finding suggests the absence of restriction site for Taq1 enzyme. However, the Dde1 digest results in bands 369bp and 319bp segregated amongst the family members. The pattern of inheritance of the 369bp fragment in this family suggested that both the patient's mother and aunt are not carriers and that the patient's factor IX gene could have undergone a de novo mutation producing a defective factor IX gene responsible for the hemophilia B. This is supported by the fact that no family history of hemophilia B is indicated in the other male members within the family.

Factor IX↗
PubMed1996

Human T lymphotropic virus type II (HTLV-II): epidemiology, molecular properties, and clinical features of infection.

Human T lymphotropic virus, type II (HTLV-II), infection has been shown to be endemic in a number of American Indian populations, and high rates of infection have also been documented in intravenous drug abusers in urban areas throughout the world. Although the role of HTLV-II in human disease has yet to be clearly defined, there is accumulating evidence that like HTLV-I, infection may also be associated with rare lymphoproliferative and neurological disorders. In this article we review and summarize the epidemiology, molecular properties and clinical features of HTLV-II infection.

Amino Acid Sequence↗
PubMed1996

Identification and characterization of a new and distinct molecular subtype of human T-cell lymphotropic virus type 2.

Molecular studies have demonstrated the existence of at least two major subtypes of human T-cell lymphotropic virus type 2 (HTLV-2), designated HTLV-2a and HTLV-2b. To further investigate the heterogeneity of this family of viruses, we have characterized the HTLV-2 subtypes present in several urban areas in Brazil. DNAs from peripheral blood mononuclear cells of a large number of infected individuals, the majority of whom were intravenous drug abusers, were analyzed by using PCR with restriction fragment length polymorphism and nucleotide sequencing analysis. Restriction fragment length polymorphism analysis of the env region suggested that all individuals were infected with the HTLV-2a subtype, and this was confirmed by nucleotide sequence analysis. In contrast, nucleotide sequence analysis of the long terminal repeat demonstrated that although the viruses were more related to the HTLV-2a than to the HTLV-2b subtype, they clustered in a distinct phylogenetic group, suggesting that they may represent a new and distinct molecular subtype of HTLV-2. This conclusion was supported by nucleotide sequence analysis of the pX region, which demonstrated that the Tax proteins of the Brazilian viruses differed from that of prototype HTLV-2a isolates but were more similar to that of HTLV-2b in that they would be expected to have an additional 25 amino acids at the carboxy terminus. In transient expression assays, the extended Tax protein of the prototype HTLV-2a subtype. The studies suggest that the Brazilian viruses analyzed in this study, while being phylogenetically related to the prototypic HTLV-2a seen in North America, are phenotypically more related to HTLV-2b and can be justifiably classified as a new molecular subtype, which has been tentatively designated HTLV-2c.

Amino Acid Sequence↗
PubMed1996

Amplification of Bcl I region of the factor VIII gene by PCR.

A study was initiated to amplify by polymerase chain reaction (PCR), a short factor VIII gene fragment containing the Bcl I restriction site from hemophilia patients using published primer sequences. Preliminary findings indicated that the resulting fragment is 142 bp long. This fragment, when digested with Bcl I restriction enzyme produced two fragments, 99 bp and 43 bp in length. Polymorphism in the Bcl I region can be used to detect carrier state in the family members of the hemophiliacs.

Factor VIII↗
PubMed1995

Identification of human T cell lymphotropic virus type IIa infection in the Kayapo, an indigenous population of Brazil.

Human T cell lymphotropic virus type II (HTLV-II) infection is endemic in a number of indigenous populations in North, Central, and South America. In the present study we have employed serological and molecular methods to identify HTLV-II infection in Indian communities in the Amazon region of Brazil. Sera (1324) from 25 different Indian communities were analyzed by ELISA and Western blot. One hundred and four samples (7.8%) from a number of culturally distinct and geographically unrelated populations were found to have reactivities consistent with HTLV-II infection. Of these, 67 were from the Kayapo Indian communities, which had an overall seroprevalence rate of greater than 30%. In addition, high seroprevalence rates were observed in three other communities, the Munduruku, Arara do Laranjal and the Tyrio, suggesting that there are additional foci of endemic infection in the Amazon region. In the Kayapo, seroprevalence rates tended to increase with age, supporting the importance of sexual transmission of the virus, and family studies demonstrated that vertical transmission is also an important route of infection. Restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis of a region of the env gene demonstrated that the Kayapo are infected with the HTLV-IIa subtype. Moreover, nucleotide sequence analysis of the LTR demonstrated that this belonged to a distinct HTLV-IIa phylogenetic group. The identification of HTLV-IIa in the Kayapo is, as far as we are aware, the first identified endemic focus of infection by this subtype of HTLV-II in the Americas.

Adolescent↗
PubMed1994

The increasing importance of vitamin B12 deficiency as a contributing factor to anemia in Malaysia.

A comparative study was done to determine the profile of vitamin B12 and folate status in Malaysians during two different periods. For the period of 1987/88, we analysed a total of 9,162 cases (inpatients) referred for vitamin B12 estimation and 10,290 cases for folate estimation. We found that 2.6% were vitamin B12 deficient and 31.2% were folate deficient. For the period of 1992/93, of the 9,962 cases assayed, 8.2% were found to be vitamin B12 deficient whereas 7.6% of the 10,355 cases referred were folate deficient. Vitamin B12 and folate were assayed either using microbiological or radioassays. These findings indicate that there appears to be a change in the status of both vitamin B12 and folate over the five year interval.

Anemia↗
PubMed1991

Nonhypercholesterolemic effects of a palm-oil diet in Malaysian volunteers.

The effects on serum lipids of diets prepared with palm olein, corn oil, and coconut oil supplying approximately 75% of the fat calories were compared in three matched groups of healthy volunteers (61 males, 22 females, aged 20-34 y). Group I received a coconut-palm-coconut dietary sequence; group II, coconut-corn-coconut; and group III, coconut oil during all three 5-wk dietary periods. Compared with entry-level values, coconut oil raised the serum total cholesterol concentration greater than 10% in all three groups. Subsequent feeding of palm olein or corn oil significantly reduced the total cholesterol (-19%, -36%), the LDL cholesterol (-20%, -42%%) and the HDL cholesterol (-20%, -26%) concentrations, respectively. Whereas the entry level of the ratio of LDL to HDL was not appreciably altered by coconut oil, this ratio was decreased 8% by palm olein and 25% by corn oil. Serum triglycerides were unaffected during the palm-olein period but were significantly reduced during the corn-oil period.

Adult↗
PubMed1990

Platelet function studies in women on oral contraceptive pills.

A study was conducted on a total of 100 women attending the Family Planning Clinic in Kuala Lumpur. 50 took combined low-dose estrogen and progesterone pills for a year or more and the other 50 used different methods of birth control. Platelet aggregation, ATP release, Thromboxane B2, and 6-keto-prostaglandin F1alpha estimations were made to evaluate the effect of oral contraceptives (OCs) on platelet function and prostanoid production. The results showed no significant differences in the parameters measured in the 2 groups investigated. These findings are comparable to those reported by other studies, suggesting relatively low risk, if any, of thrombosis in OC users.

Asia↗
PubMed1989

The erythrocyte sedimentation rate, C-reactive protein, plasma fibrinogen and viscosity in chronic renal disease patients with infection.

The sensitivity of the C-reactive protein (CRP) measurement as an indicator for infection in patients with chronic renal disease was compared to that of ESR, fibrinogen and plasma viscosity measurements. The ESR, fibrinogen and plasma viscosity did not correlate with the presence of infection, whereas the CRP level was elevated in the majority of patients with infection/fever and decreased when fever subsided.

Adolescent↗
PubMed1988

Morphogenesis of yellow fever virus 17D in infected cell cultures.

The morphogenesis of yellow fever virus replication was examined in infected Vero cell cultures. Penetration and uncoating occurred by endocytosis with the formation of coated vesicles, similar to that demonstrated for other enveloped and unenveloped viruses. Inclusion bodies associated with newly formed nucleocapsids were evident in the perinuclear region during the growth cycle. No evidence of RNA synthesis in the vicinity of the inclusion bodies was obtained by autoradiography, suggesting that genome replication and assembly of viral nucleocapsids occur at separate cytoplasmic sites. An excessive proliferation of membrane-bound organelles involving both vacuoles and endoplasmic reticula was the most striking feature of virus-infected cells late in infection. No morphological changes in the appearance of nuclei or mitochondria were detected. Virus release appeared to occur by movement of nascent virions through the proliferated endoplasmic reticula followed by exocytic fusion of virus-containing vesicles with the plasmalemma. A possible mechanism whereby the internal nucleocapsid acquires an outer envelope is discussed.

Animals↗