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Biomedical subjects

H Rabbani

Publications and source records attributed to H Rabbani.

29 records · Page 2Linked to original sources
PubMed1995

Molecular cloning, characterization, and chromosomal localization of a human lymphoid tyrosine kinase related to murine Blk.

Triggering of Ag receptors on lymphocytes induces rapid phosphorylation of several receptor-associated protein tyrosine kinases (PTKs), implicating their role in controlling cellular growth and differentiation. In this study, we report the cloning of a human cDNA encoding a nonreceptor PTK with a calculated M(r) of about 58 kDa. The kinase has an overall amino acid identity of approximately 87% with the murine Blk. However, in the unique domain there is only 58% homology and an insertion of six amino acids in the N-terminal region. The nature of this insertion suggests a functional role in membrane attachment. Northern blot analysis showed expression in all stages of B cell development and in T cell lines. The message was not observed in the nonlymphoid tissues examined. In contrast, expression of murine blk in plasma cells and T lymphocytes has not been reported. Importantly, transcripts were seen in human embryonic liver as early as 7.5 wk of gestation before the rearrangement of Ig H chain locus. Furthermore, transcripts were detected in human thymocytes and not in mature T cells. Southern blot analysis revealed polymorphism of this gene in a Caucasian population but not in a Gambian population, indicating a recent origin of this polymorphism. The gene was localized to chromosome 8p22-23. The homology at the protein level suggests that this kinase may be the human homologue of murine Blk. Expression of BLK in immature T cells suggests that BLK may play an important role in thymopoiesis.

Amino Acid Sequence↗
PubMed1995

The influence of gene deletions and duplications within the IGHC locus on serum immunoglobulin subclass levels.

To study the influence of heterozygous gene deletions and duplications in the human IGHC region on serum concentrations of antibodies, we have analyzed the IgG subclass levels in a large number of individuals from three different populations. Our results show that heterozygous gene deletions of the C gamma 1, C gamma 2, or C gamma 4 genes are all associated with a lower mean serum level of the affected subclass whereas duplication of the C gamma 2 or C gamma 4 genes result in either no change (IgG2) or a slightly elevated (IgG4) level of serum immunoglobulins.

Gene Deletion↗
PubMed1995

Prevalence, genetics and clinical presentation of chronic granulomatous disease in Sweden.

To estimate the prevalence of chronic granulomatous disease (CGD) in Sweden, an inquiry asking for known and possible CGD cases was mailed to paediatric, internal medicine and infectious disease departments all over Sweden. The detected patients were characterized as to genetics and the clinical presentation. Twenty-one patients (belonging to 16 different families) were found, corresponding to a prevalence of approximately 1/450,000 individuals. The patients with X-linked disease, lacking a functional gp91phox protein (n = 12), comprised 57% and 43% of the patients had an autosomal recessive (AR) disease lacking p47phox (n = 7) or p67phox (n = 1), respectively. All unrelated patients with X-linked disease displayed different gene abnormalities such as point mutations predicting nonsense (n = 3), missense (n = 1) or splice site mutations (n = 2), but also a total deletion and a unique 40 base pair duplicature insertion. The patients with p47phox-deficiency showed a GT deletion at a GTGT tandem repeat, and the p67phox-deficient patient displayed a heterozygous in-frame deletion of AAG combined with a large deletion in the other allele. Three patients died during the study period, two from pseudomonas cepacia infections. Patients with X-linked disease had more frequent infections (mean of 1.7 per year), than the patients with AR inheritance (0.5 infections per year). The most common infections were dermal abscesses (n = 111), followed by lymphadenitis (n = 82) and pneumonias (n = 73). Inflammatory bowel disease-like symptoms, mimicking Crohn's disease of the colon, was seen in three CGD patients.

Adolescent↗
PubMed1995

Genetics of IgA deficiency.

IgA deficiency is the most common humoral defect in man and results in an increased susceptibility to respiratory tract and gastrointestinal infections. Both clinical and genetic data support a close relationship with common variable immunodeficiency, a disease which involves not only IgA and IgG production, but also, in half of the patients, IgM. It is likely that the two disorders represent an allelic condition with a variable expression of a common gene defect which is thought to be involved in the regulation of immunoglobulin class switching. It is possible that a single, autosomally inherited gene with a limited penetrance is responsible for the development of both these defects.

Gene Expression Regulation↗
PubMed1993

Novel human immunoglobulin heavy chain constant region gene deletion haplotypes characterized by pulsed-field electrophoresis.

Fifteen patients with selective IgG1 deficiency were screened for immunoglobulin H chain C region locus (IGHC) gene deletions and three deletion haplotypes were found: del G1, del G1-G4 and del G4. These haplotypes, together with four deletion haplotypes described by us previously (del G1 (NY), del G1 (VIT) del G1-G2 (NY) and del G2-G4 (HJE)), were further characterized using pulsed-field gel electrophoresis (PFGE) to determine the physical extent of the deletions. The MluI fragment sizes confirmed the deletions, although the deduced sizes of the most extensive deletions indicated that material had been inserted into the locus.

Electrophoresis, Gel, Pulsed-Field↗
PubMed1993

A 40-base-pair duplication in the gp91-phox gene leading to X-linked chronic granulomatous disease.

Chronic granulomatous disease (CGD) is characterized by the inability of the patients' phagocytic leukocytes to generate superoxide. Therefore, these cells fail to kill certain bacteria and fungi. As a result, patients with CGD suffer from recurrent, life-threatening infections with these micro-organisms. Superoxide is produced by NADPH oxidase, a multicomponent enzyme exclusively present in phagocytic leukocytes. The most common form of CGD is X-linked, originating from a deficiency of the high-molecular-weight subunit of cytochrome b558 (gp91-phox). Here we describe a patient suffering from X-linked CGD due to a 40-base-pair duplication in exon 7 of the CYBB gene coding for gp91-phox, predicting a frameshift, substitution of 22 amino acids and a premature stop codon at amino-acid position 253. The mother as well as the grandmother of this patient were proven to be heterozygous for this mutation; the father and sister were normal. However, the great-grandmother proved to have normal oxidative functions, suggesting that the mutation occurred three generations ago. This is the first description of a nucleotide duplication leading to CGD.

Amino Acid Sequence↗
PubMed1981

Single-dose ampicillin therapy for severe shigellosis in Bangladesh.

To evaluate a more economical regimen for severe shigella dysentery, treatment with single-dose (SD) ampicillin (100 mg/kg) was compared in a randomized trial with results obtained in a conventional five-day (100 mg/kg per 24 hr) multiple-dose (MD) course. Clinical relapse occurred in one of 23 SD children, no SD or MD adults, and none of 18 MD children. Bacteriologic failures were observed in six of 26 adults compared with one of 24 MD adults (P = 0.05). Four of 10 SD children younger than four years of age failed bacteriologically, compared with one MD child. In SD children, lower ampicillin levels were significantly associated with bacteriologic failure and younger age. Resistance of Escherichia coli to ampicillin, although transiently less in SD patients, was equal in MD and SD patients two weeks after therapy. Thus, in highly endemic areas SD ampicillin is clinically effective therapy for ampicillin-sensitive shigellosis in patients older than four years of age.

Adult↗
PubMed1979

Identification of gallbladder typhoid carriers by a string device.

The efficiency of a gelatin capsule containing a nylon string for collection of duodenal specimens was investigated in carriers of Salmonella typhosa (typhi). Cultures of duodenal specimens obtained by means of the string capsule were compared with cultures of duodenal specimens obtained by a conventional duodenal tube and with stool cultures Duodenal contents obtained with either the string or tube were more often positive for S. typhosa than were stool cultures. The string, which is as efficient as tube collection but simpler and more comfortable, may be useful in identifying carriers of S. typhosa.

Adult↗
PubMed1978

Single-dose doxycycline for cholera.

To determine the efficacy of single-dose doxycycline in the treatment of cholera, we carried out a randomized prospective trial in 65 patients. Treatment consisted of either a single dose of 200 mg of doxycycline (or 4 mg/kg in patients less than 15 years old) or multiple doses of doxycycline, 500 mg over 4 days (or 10 mg/kg in patients less than 15 years old). There were no differences between the groups in the volumes of intravenous fluid required, volumes of diarrheal stool, or durations of diarrhea. The mean duration of positive stool cultures for Vibrio cholerae was similar for the two groups, although in both groups several patients continued to excrete Vibrios in the stool for more than 3 days. Blood levels of antibiotic demonstrated that the doxycycline was absorbed in spite of the rapid transit time associated with severe diarrhea. These results suggest that although tetracycline remains the drug of choice for cholera, doxycycline is a reasonable alternative, and that a single dose of 200 mg (4 mg/kg in children) is effective clinically.

Adult↗