Search PubMed⌕ Search

Biomedical subjects

A Hameed

Publications and source records attributed to A Hameed.

89 records · Page 5Linked to original sources
PubMed1989

Cytolysis by Ca-permeable transmembrane channels. Pore formation causes extensive DNA degradation and cell lysis.

This study investigates the effect of the purified membrane pore formers, staphylococcal alpha-toxin and CTL perforin, on target cell lysis as measured by 51Cr release and on nuclear damage as measured by DNA degradation and 125IUdR release. Both pore formers cause dose-dependent cell lysis, which is accompanied by DNA release. The ratio of DNA/Cr release depends on the nature of target cell and shows the same pattern as the ratio of release of the two markers reported for CTL-mediated lysis of the same targets. DNA degradation is dependent on the presence of intracellular Ca in the target cell and is totally blocked if Ca is chelated by Quin 2 intracellularly and EGTA extracellularly. DNA degradation, in addition, is inhibited by the lysosomotropic agents NH4Cl, chloroquine, and monensin. rTNF doubles the degree of DNA degradation mediated by alpha-toxin in 3-h assays. We conclude that pore formers alone can mediate DNA degradation. In addition, they may promote the uptake of other factors and thereby accelerate their time course of action. DNA degradation by pore formers requires active target participation in a pathway that is dependent on intracellular Ca and lysosomes. These aspects of target lysis resemble CTL- and NK cell-mediated cytolysis.

Aminoquinolines↗
PubMed1988

Characterization of three serine esterases isolated from human IL-2 activated killer cells.

Human peripheral blood mononuclear cells, activated for 14 to 20 days with 1000 U/ml rIL-2, develop strong cytotoxicity for NK sensitive and resistant targets. This process is accompanied by the acquisition of cytoplasmic granules in approximately 60% of the cells and by the expression of esterase activity cleaving the synthetic substrate BLT. The esterase activity, localized in the cytoplasmic granules, was purified and characterized. Three proteins with 3H-DFP binding activity were isolated and had the following properties. Following the proposed nomenclature by Masson et al., the esterases were named human granzymes 1, 2, and 3. Human granzyme 1 on SDS-PAGE has an unreduced relative m.w. of 43,000 and can form disulfide-linked oligomers of relative higher m.w. All forms of granzyme 1 bind 3H-DFP. Upon reduction, granzyme 1 migrates with Mr 30,000 on SDS-PAGE. Additional proteolytic fragments of Mr 24,000 and Mr 28,000 are observed in some reduced preparations. Granzyme 1 cleaves the substrate BLT and appears homologous with murine granzyme A. Human granzyme 2 has an unreduced relative m.w. of 30,000; after reduction, it migrates at Mr 32,000. Even though granzyme 2 binds 3H-DFT, it does not cleave BLT. Human granzyme 2 has properties similar to those of murine granzymes B-H. Human granzyme 3 has unreduced and reduced relative m.w. of 25,000 and 28,000, respectively. It is active in cleaving the substrate BLT. A murine analog for human granzyme 3 has not been described previously. N-terminal sequencing of the purified human granzymes revealed that human granzyme 1 is the gene product of human Hanuka factor cDNA clone and that it represents the human homolog to murine granzyme A. Similarly, human granzyme 2 revealed absolute identity with cDNA-derived N-terminal sequence of a putative human lymphocyte protease cDNA clone.

Amino Acid Sequence↗
PubMed1988

Structure and function of human perforin.

Perforin (P1) is a cytolytic protein with similarity to complement component C9. P1 has been described as a unique component of murine cytolytic T-cell and rat natural killer cell granules Previous studies indicated that human granules and P1 differed from murine granules and P1 in that they appeared to be cytolytically less active and lacked the haemolytic activity characteristic of P1. It has been suggested that P1, like C9, is under the control of the homologous restriction factor. Here we determine the primary structure of human P1, re-examine its functional properties, and address the question of homologous restriction.

Amino Acid Sequence↗
PubMed1988

Isolation and characterization of cytotoxic granules from human lymphokine (interleukin 2) activated killer cells.

Cytotoxic granules were isolated from human lymphokine-activated killer (LAK) cells and analyzed for their biochemical properties. Isolated granules of approximately 85-95% purity were obtained by differential centrifugation followed by discontinuous Percoll gradient centrifugation. The murine lymphocyte granule marker N-alpha-carbamazepine-L-lysine thiobenzyl ester-esterase as well as cytotoxic activity toward the human tumor cell lines K562, Raji, Daudi, and CEM were associated with LAK granule fractions. Granule-associated N-alpha-carbamazepine-L-lysine thiobenzyl ester-esterase activity increased in recombinant interleukin 2 expanded human LAK cells in parallel with cytotoxic activity for Raji tumor cell targets. Cytotoxic LAK cell granules mediated calcium-dependent killing of the tumor cell lines K562, Raji, Daudi, and CEM. However, no calcium-dependent hemolytic activity was found. Preincubation of human granules with calcium, a treatment which totally inactivates the hemolytic and cytotoxic activity of murine lymphocyte granules [perforin 1 (P1)] had no effect on human LAK granule cytotoxicity for nucleated cells. Human LAK granules appear to contain P1 detected as cross-reactive antigen detected by mouse anti-P1 and human anti-C9 in Western blot analysis. In addition, Northern blot analysis of polyadenylated RNA isolated from human LAK cells using a murine P1 complementary DNA probe showed a cross-hybridizing 2.8- to 3.0-kilobase mRNA species identical in size to murine P1 mRNA. These results demonstrate that despite similar biochemical composition, functional differences exist between human and murine cytotoxic granules. Human LAK granules were synthesized in response to recombinant interleukin 2 activation and appeared in parallel with cytotoxicity for tumor targets, suggesting an important role for LAK granules in tumor cell cytotoxicity by human LAK cells.

Animals↗
PubMed1988

Function of granule perforin and esterases in T cell-mediated reactions. Components required for delivery of molecules to target cells.

Cognate T cell-mediated functions require antigen and MHC-restricted recognition of target cells. T-effector functions comprise the delivery of signals for help, for suppression, or for cell death of the target cell. In the case of the delivery of cytotoxicity and of help for B-cell antibody production, it is known that the secretory apparatus of the effector cell participates. Prior to secretion, many components of the effector cell are stored in cytoplasmic granules. Among the important and apparently constant constituents of granules are pore-forming proteins (perforins) and proteinases (granzymes). The putative role of perforin has been thought to mediate direct cytotoxicity. It is postulated here that, in addition, perforin at low concentrations may induce target-cell endocytosis through the formation of Ca channels. Localized endocytosis of the target at the contact site in turn may lead to the uptake of locally secreted effector-cell factors, such as cytotoxic factors (CTL), lymphokines (helper cells), or suppressor factors (suppressor cells). The potential importance of such a mechanism is the delivery and uptake of secreted effector-cell components into the endosomes of target cells, bypassing the need for appropriate target-cell receptors. Perforin thus may subserve two functions depending on its intragranular concentration: one, as a killer molecule, and two, as a delivery system for additional granule factors. One of the roles of esterases in T cell-mediated cognate-effector functions may be to allow recycling of the effector cell. This apparently is achieved by an active process of detachment of the effector T cell from the target cell, possibly by way of the proteolytic cleavage of adhesion molecules. Esterases are secreted, together with perforin and other factors, during granule release at the effector target-contact site, where they can cleave intercellular adhesion molecules and thus allow effector-cell recycling and attachment to new target cells. Other roles of esterases, not discussed here, may include participation directly in the cytotoxic process through uptake into the target cell. The evidence for a common intercellular molecular delivery mechanism of cognate effector T-cell function involving perforin and esterases is summarized. This concept represents a unifying hypothesis for MHC-restricted, contact-requiring, intercellular T cell-signal delivery as well as for the delivery of cytotoxicity by non-MHC-restricted T cells and natural killer cells.

Animals↗
PubMedDate not supplied

Connexin 50 mutation in a family with congenital "zonular nuclear" pulverulent cataract of Pakistani origin.

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report linkage of a three-generation family of Pakistani origin with autosomal dominant cataract "zonular nuclear" pulverulent type (CZNP) on chromosome 1q21.1. Genome wide-linkage analysis excluded all the known cataract loci except on chromosome 1q. Significantly positive 2-point lod score values (Z=3.01 at theta=0) were obtained for markers D1S305 and D1S2721, which are known to flank the gene for connexin 50 (Cx50) or gap junction protein alpha-8 (Gja8). Previously a mutation in this gene has been reported in a British family with zonular pulverulent cataract (CZP). Here we describe a second mutation (E48K) in connexin 50 that confirms the involvement of this gene in cataractogenesis.

Cataract↗
PubMedDate not supplied

Exfoliative cytology of atypical polypoid adenomyoma. A case report.

BACKGROUND: An atypical polypoid adenomyoma (APA) is a well-defined entity. It occurs in the endometrium, lower uterine segment and endocervix. It is usually composed of atypical complex glands with squamous metaplasia admixed with myofibromatous stroma. CASE: A 35-year-old female presented with one-year history of irregular menstrual periods. A diagnosis of adenocarcinoma in situ was rendered on her cervicovaginal smear. Pelvic examination revealed an enlarged uterus due to a leiomyoma. Colposcopic examination revealed a 0.6-cm, sessile, polypoid mass at the junction of the endocervix and ectocervix. A cone biopsy of the lesion showed irregular, endometrial-type glands embedded in a prominent myofibromatous stroma. The atypical glandular component of the mass demonstrated varying degrees of architectural complexity, ranging from simple to complex hyperplasia. In tissue sections the lesion was diagnosed as APA of the cervix. The patient underwent a hysterectomy for the leiomyoma. The hysterectomy specimen showed an 8.5-cm leiomyoma. The cervix and uterine corpus revealed no residual APA. CONCLUSION: APA of the cervix should be considered among the differential diagnoses of atypical glandular cells of undetermined significance. The diagnosis of APA cannot be made on cytology; the final diagnosis requires histologic confirmation.

Adenomyoma↗
PubMedDate not supplied

Exfoliative cytology of neuroendocrine small cell carcinoma of the endometrium. A report of two cases.

BACKGROUND: In the female genital tract, neuroendocrine small cell carcinoma can occur in the endometrium as well as the cervix, ovary and vagina. This tumor has a high propensity for systemic spread and a poor prognosis. Small cell carcinoma of the endometrium is cytologically identical to its counterparts in the lung and other sites. Its characteristic appearance in a cervicovaginal smear should raise concern about small cell carcinoma. Other tumors of the uterus should be considered in the differential diagnosis, including adenocarcinoma with neuroendocrine features, small cell nonkeratinizing squamous cell carcinoma, endometrial stromal sarcoma, rhabdomyosarcoma, primitive neuroectodermal tumor, non-Hodgkin's lymphoma and metastatic breast carcinoma. CASES: Case 1 was a 59-year-old, white female, and case 2 was a 47-year-old, white female. Both patients presented with vaginal bleeding. The Papanicolaou smears in both cases had similar, characteristic exfoliative cytology. The tumor cells were small and either single or arranged in groups and files. They had barely visible cytoplasm, darkly staining nuclei with finely stippled chromatin, and inconspicuous nucleoli. The characteristic molding of the nuclei was also present. Immuno-histochemical staining for neuron-specific enolase and synaptophysin was positive in tissue sections. Pancytokeratin, vimentin, muscle-specific actin, desmin, alpha-fetoprotein, S-100, glial fibrillary acid protein, common leukocyte antigen and chromogranin were negative. CONCLUSION: When a uterine small cell carcinoma is suspected in a cervicovaginal smear, the similarity of cervical and endometrial small cell carcinoma requires a differential curettage and immunohistochemical demonstration of neuroendocrine differentiation in order to arrive at the final diagnosis.

Biomarkers, Tumor↗
PubMedDate not supplied

Detection of perforin in human peritoneal fluid T-lymphocytes.

OBJECTIVE: Perforin is a specific marker of functionally active cytotoxic T-lymphocytes (CTLs) and natural killer (NK) cells. The purpose of this study was to detect perforin-positive lymphocytes in ascites secondary to various gynecologic malignancies and nonneoplastic conditions. STUDY DESIGN: Fifty-three unselected peritoneal fluid specimens submitted for cytopathologic diagnosis were used. A monoclonal antibody to human perforin was used to examine its expression in mononuclear cells from ascites specimens using a standard immunoperoxidase technique. RESULTS: Strong perforin expression by 15-30% of mononuclear cells was detected in 10 of the 13 patients with severe alcoholic hepatitis, 3 of the 5 patients with chronic active hepatitis without cirrhosis and 1 patient with an autoimmune disorder of unknown etiology. The lymphocytes showed variable positivity for T cell markers (CD2, CD4, CD8 and CD56). Perforin was not detected in ascites specimens obtained from patients with such nonneoplastic disorders as cirrhosis or end stage renal or cardiac failure. Similarly, ascites specimens from patients with various gynecologic malignancies were negative for perforin-positive lymphocytes. CONCLUSION: The detection of cytotoxic lymphocytes in peritoneal fluid obtained from patients with liver injury may have implications for the pathogenesis of this disease.

Antibodies, Monoclonal↗
PubMedDate not supplied

An epidemological study of smoking at Abbottabad.

BACKGROUND: Smoking is a type of environmental pollution and is injurious to health. We conducted an epidemiological study of different forms of smoking like cigarette, Hookah (Hubble-Bubble) and cigar in Abbottabad. METHODS: 600 randomly selected subjects residing in different localities of Abbottabad were included. A specifically designed questionnaire was filled. RESULTS: Out of the study population 200 (33%) were found to be smoking. CONCLUSIONS: A significant proportion of Abbottabad population smokes. This city is supposed to be a relatively less polluted hill station where a lot of people come for vacations.

Humans↗
PubMedDate not supplied

Effect of oral and injectable contraceptives on serum calcium, magnesium and phosphorus in women.

BACKGROUND: This study aims at evaluating serum calcium, magnesium and phosphorus levels in women taking oral and injectable contraceptives. METHODS: Serum calcium, magnesium and phosphorus were measured in 50 women taking oral contraceptives (Lofeminal) and 50 women taking injectable contraceptive (Depo-medroxy progesterone acetate and Norigest). These women were used as controls before starting these contraceptives. RESULTS: There was significant decrease in serum levels of calcium, magnesium and phosphorus in women taking oral contraceptives but there was significant increase in these minerals in women taking injectable contraceptives. CONCLUSIONS: It is suggested that these contraceptives should be used with due care and with proper investigations of the women before and during the therapy.

Adult↗
PubMedDate not supplied

Effect of oral and injectable contraceptives on serum electrolytes, weight and blood pressure.

BACKGROUND: Since the introduction of oral and injectable contraceptives, many metabolic side effects have been reported. The use of oral contraceptive has been shown to be associated with increased level of serum electrolytes, but decrease in levels of serum electrolytes has been reported in women using injectable contraceptives. This study evaluated serum electrolytes, weight and blood pressure in women taking oral and injectable contraceptives because these changes have adverse effects on the health and economy of the subject. METHODS: Serum electrolytes, weight and blood pressure were measured in 50 women taking oral contraceptive (Lofeminal) and 50 women taking injectable contraceptives (Depomedroxy progesterone acetate and Norigest). The same women served as control before starting these contraceptives. RESULTS: There was a significant increase in serum sodium and chloride but significant decrease in serum potassium and bicarbonate level in women taking oral contraceptive. There was non-significant decrease in serum electrolytes in women taking injectable contraceptives. There was significant increase in weight and blood pressure of women taking these contraceptives.

Adult↗
PubMedDate not supplied

Cholinergic crisis following treatment of postoperative urinary retention with distigmine bromide.

Distigmine bromide is a long-acting anticholinesterase, available for the treatment of postoperative urinary retention. Its effectiveness is unproven and administration may be hazardous. We describe a case in which oral distigmine bromide was used for postoperative retention, resulting in a potentially life-threatening 'cholinergic crisis'. We review the literature and conclude that the use of oral distigmine bromide in postoperative urinary retention is not justified.

Adult↗