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Biomedical subjects

A Islam

Publications and source records attributed to A Islam.

At least 91 records · Page 5Linked to original sources
PubMed1990

Bone lining (endosteal) cells and hematopoiesis: a light microscopic study of normal and pathologic human bone marrow in plastic-embedded sections.

Human trabecular bone that encloses the bone marrow (BM) is covered by a single layer of thin, sometimes inconspicuous, flat, elongated (spindle-shaped) endothelium-like cells with a round or oval nucleus. These "bone lining" cells, or endosteal cells (EC), form a continuous membrane (endosteum) over the trabecular bone surfaces. In most cases, the composition and thickness of these cells do not vary unless the cells are in intimate contact with hematopoietic tissue. In that instance, they are seen as a single layer adjacent to hematopoietic tissue or as a zone of tightly packed or loosely arranged mononuclear (hematopoietic) cells, some apparently originating from the endosteum. In a reparative process, such as following BM harvest, during which bony trabeculae (BT) are mechanically fractured, these cells are seen giving rise to osteoprogenitor (osteoblasts and osteoclasts) cells. Occasionally, the EC appear similar to BM stromal cells (morphologically and by their association with collagen/reticulin fibers) and are best seen at or near the BT that are cut tangentially. Short processes extending from the EC towards the underlying osteocytes have also been observed, suggesting that a channel of communication exists between them and osteocytes. Our observations, coupled with the experimental findings of others (i.e., that hematopoietic stem cells are concentrated near the endosteum, that cells responsible for BM and stroma regeneration are derived from the endosteal layer, and that high concentrations of hematopoietic colony-stimulating factors are produced there), indicate that, in addition to functioning as a simple membranous covering layer for BT, the endosteum helps to support osteocytes and maintains mineral homeostasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow↗
PubMed1990

Sea snake (Microcephalophis gracilis) hemoglobin: primary structure and relationships to other forms.

The hemoglobin of the sea snake Microcephalophis gracilis was purified and the primary structure of the alpha and beta chains determined. This is the first sea snake hemoglobin structure characterized, and apparently also the first complete structure of any snake hemoglobin (an alpha chain of a viper was known), allowing judgments of reptilian variants. Variations between the sea snake form and other reptilian forms are large (52-65 differences for the alpha chains), of similar order as those between the sea snake and avian (56-65 differences) or human (58 differences) forms. Functionally, 19 residues at alpha/beta contact areas and 7 at heme contacts are exchanged in relation to the human alpha and beta chains. Four positions of the sea snake hemoglobin contain residues thus far unique to this form. However, all replacements appear compatible with conserved overall functional properties.

Amino Acid Sequence↗
PubMed1990

Verapamil corrects abnormalities in norepinephrine metabolism of brain synaptosomes in CRF.

Abnormalities in norepinephrine (NE) metabolism of brain synaptosomes occur in chronic renal failure (CRF), and this has been attributed to the parathyroid hormone (PTH)-induced accumulation of calcium in synaptosomes. The present study examined the effect of treatment with the calcium-channel blocker verapamil on NE content, release, and uptake, on Na(+)-K(+)-ATPase activity, and on calcium content of brain synaptosomes from rats with 21 days of CRF. Verapamil treatment of normal rats for 21 days did not affect synaptosomal NE content, release, or uptake, Na(+)-K(+)-ATPase activity, or calcium content. Rats with 21 days of CRF displayed a significant (P less than 0.01) reduction in their synaptosomal NE content, release, and uptake, an increase in Na(+)-K(+)-ATPase activity, and a significant (P less than 0.01) increase in calcium content of synaptosomes. The treatment of CRF rats with verapamil normalized synaptosomal NE content and release and Na(+)-K(+)-ATPase activity, produced a significant (P less than 0.01) improvement in NE uptake, and prevented the accumulation of calcium in synaptosomes. The data of the present study are consistent with the notion that the abnormalities in synaptosomal NE metabolism and Na(+)-K(+)-ATPase in CRF are mainly the result of PTH-induced accumulation of calcium in synaptosomes and could be prevented by a calcium-channel blocker.

Animals↗
PubMed1990

Effect of verapamil on CRF-induced abnormalities in phospholipid contents of brain synaptosomes.

Chronic renal failure is associated with significant reductions in total phospholipids, phosphatidylinositol, phosphatidylserine, and phosphatidylethanolamine of brain synaptosomes. These derangements in synaptosomal phospholipid metabolism were attributed to the state of secondary hyperparathyroidism of chronic renal failure (CRF) and the parathyroid hormone-induced accumulation of calcium in synaptosomes. This study examined whether a calcium channel blocker, verapamil, would prevent this synaptosomal calcium accumulation and correct the abnormalities in synaptosomal phospholipids in CRF. Verapamil treatment of normal rats for 21 days did not affect synaptosomal content of calcium or phospholipids. CRF of 21 days' duration was associated with a significant (P less than 0.01) increase in synaptosomal calcium (10.2 +/- 0.5 vs 7.4 +/- 0.6 nmol/mg protein) and a significant reduction (P less than 0.01) in total phospholipids (397 +/- 12 vs 529 +/- 19 nmol phospholipid P/mg protein), phosphatidylinositol (2.7 +/- 0.22 vs 4.6 +/- 0.27 nmol phospholipid P/mg protein), and phosphatidylserine (37 +/- 1.9 vs 83 +/- 5.2 nmol phospholipid P/mg protein). Simultaneous treatment of CRF rats with verapamil for 21 days reversed the synaptosomal abnormalities in calcium and phospholipid contents. Our data support the notion that the effect of excess parathyroid hormone of CRF on synaptosomal phospholipids is mainly due to the parathyroid hormone-induced calcium accumulation.

Animals↗
PubMed1990

Corneal vital staining with gentian violet.

We have used 0.5% gentian violet solution as a corneal vital stain in 112 patients with variable degrees of corneal involvements and in 40 normal eyes as control. Gentian violet stained the epithelial defects and degenerated epithelial cells of cornea. The stain persisted 3-5 minutes and disappeared by 8-10 minutes. There was no cross infection from dye use. The dye did not hamper usual process of repair of corneal lesions. It is found highly feasible, with a sensitivity about 100% and specificity about 95%, with some minor side effects. Thus it could be an excellent method in community ophthalmology for early diagnosis of corneal affections, thereby commencing prompt and appropriate treatment in early stage.

Corneal Diseases↗
PubMed1989

Oral rehydration formula containing alanine and glucose for treatment of diarrhoea: a controlled trial.

OBJECTIVE: To determine whether adding L-alanine to the glucose based oral rehydration solution recommended by the World Health Organisation would improve its efficacy in treating acute diarrhoea. DESIGN: Randomised double blind controlled trial of oral rehydration solution containing L-alanine and glucose. SETTING: Inpatient service of a hospital treating diarrhoea. PATIENTS: 97 Male patients aged 6-59 years admitted to the hospital with acute and severe dehydration due to diarrhoea associated with Vibrio cholerae or enterotoxigenic Escherichia coli. Forty nine received the standard glucose based oral rehydration solution (control group) and 48 this solution with alanine added (study group). INTERVENTIONS: All of the patients received rapid intravenous acetate solution for the initial four hours after admission, which fully corrected the signs of dehydration. They were then admitted to the study and randomised. Immediately after the intravenous treatment oral rehydration treatment was started. All of the patients received oral tetracycline for 48 hours, starting 24 hours after start of the study. If signs of dehydration reappeared during oral treatment patients were given rapid intravenous acetate solution until they were fully corrected and then continued to take the assigned oral rehydration solution. END POINT: Passage of the last watery stool. MEASUREMENTS AND MAIN RESULTS: The median stool output/kg body weight during the initial 24 hours of oral rehydration treatment and until diarrhoea stopped was reduced in the study group compared with the control group from 309 ml to 196 ml and from 393 ml to 236 ml respectively. Intake of oral rehydration solution and intravenous acetate solution was reduced from 455 ml to 308 ml and from 616 ml to 425 ml respectively. Two patients in the study group compared with 18 patients in the control group required unscheduled rapid intravenous acetate solution to correct signs of dehydration during oral rehydration treatment. CONCLUSION: Oral rehydration solution containing L-alanine was considerably better than standard oral rehydration solution at reducing the severity of symptoms and the need for fluid of male patients with diarrhoea associated with V cholerae and enterotoxigenic E coli.

Adolescent↗
PubMed1989

Primary structure of the hemoglobin beta-chain of rose-ringed parakeet (Psittacula krameri).

The primary structure of Rose-ringed Parakeet hemoglobin beta-chain was established, completing the analysis of this hemoglobin. Comparison with other avian beta-chains show variations smaller than those for the corresponding alpha-chains. There are 11 amino acid exchanges in relationship to the only other characterized psittaciform beta-chain, and a total of 35 positions are affected by differences among all avian beta-chains analyzed (versus 61 for the alpha-chains). At three positions, the Psittacula beta-chain has residues unique to this species. Three alpha 1 beta 1 contacts are modified, by substitutions at positions beta 51, beta 116, and beta 125.

Amino Acid Sequence↗
PubMed1989

Plastic embedded core biopsy: a complementary approach to bone marrow aspiration for diagnosing acute myeloid leukaemia.

Bone marrow aspirates and biopsy specimens were taken at diagnosis from 51 patients with acute myeloid leukaemia (AML). The diagnosis was based on morphological and cytochemical analyses, and the leukaemias were classified by FAB criteria. A considerable difference was observed between the results of bone marrow aspirates and the findings of plastic-embedded bone marrow biopsy specimens, particularly in marrow cellularity, extent of blast cell infiltration, and cell type involved in the leukaemic process. The myelomonocytic cell type seemed to predominate in the sections. In four cases there was considerable marrow infiltration with maturing, but dysplastic, granulocytic cells in the sections, but not in the aspirate smears. Features of potential prognostic importance, such as bone marrow infiltration with inflammatory cells, were easily recognised and quantified in the sections. These results indicate that plastic embedded bone marrow biopsy sections complement the findings of bone marrow aspiration in the diagnosis of AML and may also provide information of independent prognostic importance that cannot be obtained by other means.

Biopsy, Needle↗
PubMed1989

Effect of chronic renal failure and parathyroid hormone on phospholipid content of brain synaptosomes.

The effects of 21 days of chronic renal failure (CRF) with and without excess parathyroid hormone (PTH) and those of 21 days administration of intact PTH on phospholipids and cholesterol contents of rat brain synaptosomes were examined. CRF and PTH treatment were associated with a significant (P less than 0.01-0.02) reduction in the synaptosomal contents of total phospholipids, phosphatidylinositol (PI), phosphatidylserine (PS), and phosphatidylethanolamine (PE). Parathyroidectomy (PTX) prior to the induction of CRF prevented the decrements in the synaptosomal contents of total phospholipids, PI, PS, and PE. The synaptosomal contents of these phospholipids in CRF-PTX rats were not different from those in normal rats despite CRF. There were no significant changes in the cholesterol content of the synaptosomes in the various experimental groups of animals. The data show that CRF affects synaptosomal metabolism of total phospholipids, PI, PS, and PE, and these derangements are due to the state of secondary hyperparathyroidism of renal failure. The decrements in the content of PI, PS, and PE could be, at least in part, responsible for the previously reported abnormalities in the neurotransmitter functions of brain synaptosomes in CRF and could underlie some of the abnormalities in central nervous system dysfunction in uremia.

Animals↗
PubMed1989

Rapid separation and quantitation of major phospholipids in biological samples by combined high-performance liquid chromatography and automated phosphorus analyzer.

Phospholipids extracted from tissue samples were separated by an isocratic high-performance-liquid-chromatographic (HPLC) method and simultaneously quantitated by an automated phosphorus analyzer. Results from various tissues were compared with previously published data obtained by thin-layer chromatography (TLC). Liver, heart, skeletal muscle, kidney and brain cortex synaptosomes from rats were examined. Optimal separation of major phospholipids of these tissues was achieved in a single HPLC run using a mobile phase of acetonitrile, methanol and sulfuric acid 100:2.1:0.05 (v:v:v). Recoveries of pure phospholipids injected onto the column averaged 75-80%. Similar recoveries were obtained with heart and skeletal muscle phospholipids, whereas liver, kidney and synaptosomes yielded lower recoveries (50-66%), suggesting the presence of other phospholipids in these tissues which did not elute from the column. The composition of total and individual phospholipids varied among the tissues and was generally similar to previously reported findings with TLC. The intraassay coefficients of variation ranged from 5 to 11%. We conclude that this technique is a reliable, rapid, and reproducible method for separation and quantitation of the major phospholipid species of tissues and subcellular fractions.

Animals↗
PubMed1989

Evidence for proliferation and differentiation of endosteal cells into hemopoietic cell lines in short-term liquid culture.

To study the ability of endosteal cells to spontaneously differentiate in vitro, cells isolated from the endosteal bone surface (endosteal cells) were incubated in liquid suspension cultures containing fetal calf serum and antibiotics, but without chemical inducers of differentiation. Cultures were examined daily for the appearance of morphologically recognizable mature and differentiated hemopoietic cells. Culture outcomes were uniformly consistent, showed an almost complete disappearance of the endosteal cells (which appeared as stimulated lymphoid and late stage normoblast-like cells once they are separated from the bone surfaces), and their replacement by differentiated and mature hemopoietic cells. The ability of endosteal cells to fully differentiate into mature hemopoietic cells in vitro indicates that endosteal cells represent the multipotential hemopoietic stem cells in vivo, and are equivalent of embryonal stage undifferentiated mesenchymal cells.

Animals↗
PubMed1989

In vitro growth and hemopoietic differentiation of mouse bone marrow-derived adherent stromal cells in long-term culture: formation of spheroidal bodies mimicking hemopoietic anlagen.

A novel method is reported for in vitro growth and hemopoietic differentiation of mouse bone marrow-derived adherent stromal cells in long-term marrow cultures. The cultures were done in 50 ml conical tubes with cell suspension in 10 ml of growth medium. The first stage was to form a layer of adherent stromal cells to extend over the entire area of the tube bathed by the medium. The second stage was to develop small spheroidal bodies (1 to 3 mm in diameter) firmly anchored to the substratum of adherent stromal cells. The spheroidal bodies consisted of an outer layer of stromal (primitive mesenchymal) cells, and an inner core of mostly round and primitive hemopoietic cells. Some degree of differentiation into hemopoietic cell lines was also seen in the central core of some spheroidal bodies. These findings show similarities between the spheroidal body formation and the early events of hemopoiesis in human fetal bone marrow, and suggest that the bone marrow stroma cultured in vitro is multipotential and capable of modulation and transformation into stromal and hemopoietic precursor cells.

Animals↗
PubMed1989

Electron microscopic evidence for hemopoietic and stromal cells in murine long-term bone marrow cultures.

We have generated a cell line by continuous cultivation of murine bone marrow (BM) cells in liquid phase. After more than 18 months of in vitro propagation, these cells continued to produce a mixed cell population of flat, adherent (stromal) and loose, or loosely adherent, small, round cells. Scanning electron microscopy of these cultures revealed small, round cells adhering to flat, elongated or stellar shaped stromal cells. Transmission electron microscopy of the same cultures identified the stromal cells as nonhematopoietic and fibroblastic, and the small, round cells as "hematopoietic" with features of primitive as well as more differentiated hematopoietic cells. Our results suggest that the adherent stromal cells in long-term marrow culture may contain cells with hemopoietic potential.

Animals↗
PubMed1989

Primary culture of marrow core in collagen gels: modulation and transformation of endosteal cells. I. Morphologic observations.

It has been shown that collagen gels can be used as a culture matrix for the growth and proliferation of a variety of stromal and hemopoietic cellular elements. Since collagen is a physiologic matrix and allows the simultaneous growth and proliferation of a variety of cellular elements in three dimensional fashion, we used this method to culture 2 to 3 mm segments of trephined bone marrow. The gels were constantly bathed by RPMI 1640 medium containing fetal calf serum and antibiotic. Modulation, migration and transformation of endosteal cells were apparent under phase contrast microscopy and were confirmed in histologic sections. This study demonstrates for the first time that human marrow endosteal cells - the cells which line the bony trabeculae - are inducible and capable of modulation and transformation into stromal (fibroblast-like, macrophage-like, and fat-containing cells) and hemopoietic (round or spheroidal blast-like) cells. This report provides further evidence that endosteal cells can be considered the fixed (reserve) totipotential stem cells in the human bone marrow and are the equivalent of embryonal level undifferentiated mesenchymal cells which are capable of giving rise to the many different cell types that constitute the hemopoietic organ, i.e., bone marrow.

Adult↗
PubMed1988

Primary structure of the hemoglobin alpha-chain of rose-ringed parakeet (Psittacula krameri).

The structure of the hemoglobin alpha-chain of Rose-ringed Parakeet was determined by sequence degradations of the intact subunit, the CNBr fragments, and peptides obtained by digestion with staphylococcal Glu-specific protease and trypsin. Using this analysis, the complete alpha-chain structure of 21 avian species is known, permitting comparisons of the protein structure and of avian relationships. The structure exhibits differences from previously established avian alpha-chains at a total of 61 positions, five of which have residues unique to those of the parakeet (Ser-12, Gly-65, Ser-67, Ala-121, and Leu-134). The analysis defines hemoglobin variation within an additional avian order (Psittaciformes), demonstrates distant patterns for evaluation of relationships within other avian orders, and lends support to taxonomic conclusions from molecular data.

Amino Acid Sequence↗
PubMed1988

The prevalence of Entamoeba histolytica in lactating women and in their infants in Bangladesh.

Entamoeba histolytica was studied in 33 lactating women and their infants in a periurban village in Bangladesh. Infant-mother pairs were followed for a period of 10-15 months: 67% of mothers excreted E. histolytica during the observation period, the majority for 3 months or more. Only one mother was symptomatic, with a mild, non-dysenteric diarrhoea. 58% of mothers were seropositive, several of them continuously and with a high titre, indicating past invasive infection. 67% had detectable antibodies in breast milk and 36% in saliva. Despite the high prevalence of E. histolytica in these mothers, infants were mostly uninfected: E. histolytica cysts in small numbers were found in only 2 of 1200 samples from infants aged 6 and 10 months. Several of the children were infected with Giardia lamblia. Although lower exposure to E. histolytica than to Giardia may account for the difference in infant infection rates with these parasites, defence mechanisms possibly exist which protect against E. histolytica but are ineffective against Giardia.

Adolescent↗
PubMed1988

Do bone marrow fat cells or their precursors have a pathogenic role in idiopathic aplastic anaemia?

Idiopathic aplastic anaemia (AA), aplastic anaemia of unknown aetiology, is usually defined as marrow failure with fatty replacement of hemopoietic tissue and peripheral pancytopenia. The pathophysiology is largely unknown, though many mechanisms have been hypothesized. These include the absence of or defects in hemopoietic stem cells (HSC), abnormalities of the bone marrow (BM) microenvironment, immune system disorders and abnormalities of the regulatory factors that control hemopoiesis. The characteristic feature of AA is the replacement of hematopoietically active marrow by fat cells; however, the fat cells themselves have received little attention to date, and this apparent fatty marrow infiltration has been considered a secondary phenomenon. That the marrow fat cells in AA may be abnormal and may have a pathogenic role has never been considered. This communication, postulates that AA may result from an abnormal and excessive proliferation of marrow fat cells and the displacement of the hematopoietic tissue of the marrow; and that the resultant marrow failure could be a secondary phenomenon.

Adipose Tissue↗