PubMed Health⌕ Search

Biomedical subjects

S H Khalil

Publications and source records attributed to S H Khalil.

At least 19 recordsLinked to original sources
PubMed1998

Mutation of p16, p21 or cyclin dependent kinase 4 is rare in acute lymphoblastic leukaemia.

Homozygous deletion of the p16 tumour suppressor gene (at frequencies ranging from 14% to 29%) have been implicated in the pathogenesis of acute lymphoblastic leukaemia (ALL) by several studies. We investigated the prevalence of this deletion in a group of 46 Arab patients with common ALL. Deletion of p16 was assessed in a multiplex PCR which amplified a 405 bp fragment from exon 2 of the p16 gene, and a 242 bp fragment of the ApoE lipoprotein gene which served as an internal control. Homozygous deletion of p16 in tumour cells could be readily detected in samples containing >75% blasts. Surprisingly, none of the cases in our study showed homozygous deletion of the p16 gene. We also investigated the possibility of other genetic alterations in the p16 gene or mutation in the p21 and CDK4 (not previously reported in ALL) genes which are part of the same signal transduction pathway. A heterozygous G --> A transition at nucleotide position 273 of the p16 gene was present in one patient, but did not result in an amino acid change. A C --> A transversion at codon 88 of the p21 gene, which results in replacement of a phenylalanine with a leucine at position 63, was detected in one patient. In another patient a G --> C transversion in exon 2 at codon 82 (5'-untranslated region of the CDK4 gene) was detected. Results of this study showed mutation of p16, p21 or CDK4 to be rare events in Arab ALL patients.

Cyclin-Dependent Kinase Inhibitor p21↗
PubMed1995

The Sebastian platelet syndrome. Report of the first native Saudi Arabian patient.

Sebastian platelet syndrome is an hereditary thrombocytopenia with giant platelets and inclusion bodies in the granulocytes consisting of dispersed filaments, clusters of ribosomes and a few segments of rough and smooth endoplasmic reticulum at the ultrastructural level, similar to those observed in Fechtner syndrome (a variant of the Alport syndrome)--Sebastian platelet syndrome lacks the additional clinical features such as high frequency deafness, congenital cataract, and chronic interstitial nephritis. Here we report the fourth case worldwide and the first of an Arabian ancestry.

Blood Platelets↗
PubMed1994

Immunophenotyping of childhood acute lymphoblastic leukemia in Saudi Arabia: second look.

Geographical variations in the incidence of disease are of considerable theoretical and practical importance. It has been claimed that the distribution of acute lymphoblastic leukemia (ALL) phenotypes in Saudi Arabia is different from that recorded in the Western literature. One hundred and twelve (112) patients under 15 years of age, diagnosed as ALL between January 1992 and May 1994 had immunophenotypes performed on their blast cells. Common ALL (cALL) together with pre-B-ALL, formed 86.5% of the total; B-cell 3%, T-cell 6% and null cell 4.5%. These figures are not significantly different from the Western literature. A previous claim from this institution in 1990, that both null and B-cell ALL were significantly increased compared with elsewhere, is not supported by the present figures. Age and sex distribution, and FAB classification, L1 77%, L2 20% and L3 3%, were also of the same order as described elsewhere and, in particular, there was no increase in the frequency of L3 subtype.

Adolescent↗
PubMed1992

Malformations of the eye in the exencephalic tail-short mice during its development.

Exencephalic tail-short (Ts/+) embryos were obtained from mating normal mice of Patch strain with Ts/+ mice from Babl/c strain. The most common eye malformations in the exencephalic embryos were exophthalmy, microphthalmy, eye ball irregularity and corneal opacity. Squint eye and unilateral anophthalmy occurred at a lower frequency. The eye abnormalities were recognized histologically by 11-days of gestation. The retina was retarded in development. Lens fibres were swollen and some of them appeared degenerated. Lens epithelium was protruded anteriorly, detached from the underlying lens and joined the corneal endothelium. The lens remained in close contact to the ectodermal layer, forming a thick lens stalk. At the 16-day stage, the corneal epithelium became irregular in thickness and the corneal stroma was discontinuous, having disarranged collagenous fibrils. In a few embryos the corneal endothelium was absent. In the squint-eyed embryo, the cornea bulged through the opened eyelids, while in an anophthalmic embryo it was thick and underdeveloped. Generally, the upper and lower eyelids of the exencephalic embryos were asymmetrical, and the lower lid appeared covered by a thick irregular peridermal layer.

Animals↗
PubMed1989

Regeneration of the optic tectum in larval stages of Bufo regularis Reuss after partial and total excision.

The right optic tectum of four larval stages of Bufo regularis was subjected to partial and total excision to determine the regenerative capacity of the optic tectum. Intense regenerative capacity can be observed at stage 50; the regenerated part grows to a considerable size and its structure is comparable to that of the intact part. This regenerative capacity gradually diminishes and from stage 55 onwards the decrease is pronounced. At stage 57 regenerative capacity is severly reduced and the regenerated part, if present, always has an anomalous structure.

Animals↗
PubMed1989

Histological studies of normal and mutant mouse embryo hearts (a glycogen content study).

Mutant tail-short (Ts/+) embryos are developmentally retarded compared with normal +/+ litter mates. The development of the heart of Ts/+ embryos is severely affected if the tail-short gene is transferred to a new genetic (50% A/Gr) background. The aim of the present study was to investigate the glycogen content of the sinus muscle, the cushion and the atrial and ventricular walls of the heart. In normal embryos the sinus muscle is well developed by the 15th day post coitum (d.p.c.) and is crowded with glycogen granules. In Ts/+ mutant embryos, on the other hand, the development of this muscle is retarded and it contains only a little, diffusely distributed glycogen. The atrial and ventricular walls of embryos with a normal heart are well trabeculated and contain a large quantity of glycogen granules, while in mutant embryos they are less well trabeculated and contain only a little glycogen in a diffuse of finely granular form.

Animals↗
PubMed1989

Embryonic development of the mouse, with reference to intrauterine position.

The degree of development of embryos in the same litter varied. In both the control and the experimental group the foetal weight curve followed a U-shaped course, with the lightest embryos in the intermediate position. A high incidence of split-face embryos was found in the lateral (ovarian) position in the uterus, while the highest frequency of exencephalic embryos occurred in the intermediate position.

Animals↗
PubMed1989

Structure of the eye of an adult bony fish, Gambusia (Haplochilus) schoelleri.

The study showed that the eyeball of Gambusia is spherical and that it has two thin transparent lids--a small upper lid and a larger lower lid. The cornea is composed of four layers, and the lens, which is relatively large, is covered externally by a lens capsule. The lens fibres are arranged in concentric lamellae. The ciliary body is present only on the ventral aspect of the eye. The iris is triangular and is densely pigmented with guanin crystals. As in other vertebrates, the retina consists of ten layers. The hyaloid or retinal artery lies among the optic nerve fibres. The photoreceptor cell layer is generally thick and contains rods and cones. The internal retinal envelope, the choroid coat, appears on the medial aspect of the eyeball as a thickened vascular part, referred to as the suprachoroidal layer. This layer contains a horseshoe-shaped gland, the choroid gland, the outer portion of which is surrounded by a layer of silvery guanin crystals generally termed the argentea.

Animals↗
PubMed1989

Regeneration of the caudal and pectoral fins of a bony fish, Gambusia (Haplochilus) schoelleri.

The study showed that excision of the caudal fin at basal level was followed by complete regeneration in one and a half months, whereas if it was amputated at mid-fin level, complete regeneration took two months. The findings confirm that the greater the extent of amputation, the faster the rate of regeneration. In the case of the pectoral fin, only part of which was removed, it was found that the fin completely regenerated, with recovery of its original pattern, within two months after amputation.

Animals↗
PubMed1988

Cell mediated and humoral immunity and light-chain proteinuria in rifampicin-treated tuberculous patients.

The present study was devoted to assess the humoral and cell mediated immune responsiveness in patients with pulmonary tuberculosis before and after rifampicin therapy. Skin test using PPD and PHA; Rosette forming cells test, serum IgG, M and A; and light chain proteinuria have been tested for 15 newly diagnosed tuberculous patients and 15 normal controls. Rifampicin showed an immunosuppressive effect on both cellular and humoral immune responses as well as by the advent of light chain proteinuria.

Humans↗