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Biomedical subjects

S P Clark

Publications and source records attributed to S P Clark.

13 recordsLinked to original sources
PubMed1992

Fine-needle aspiration of cystic nephroma (multilocular cyst of the kidney).

Cystic nephromas are rare tumors of the kidney most commonly affecting boys or adult females. The fine-needle aspiration cytomorphology has not yet been described. A renal cystic mass in a 56 year old female was aspirated under ultrasound guidance. Papanicolaou stained smears of the cyst fluid revealed markedly atypical cells forming papillary clusters. Subsequent nephrectomy showed a typical cystic nephroma with lining epithelium resembling that seen in the aspirate. The cytomorphology of cystic nephroma has been misdiagnosed as renal cell carcinoma in the literature. Low cellularity, absence of necrosis, and paucity of single cells are features that should raise the possibility of cystic nephroma in a cystic renal mass.

Adenocarcinoma↗
PubMed1992

MALIGNED: a multiple sequence alignment editor.

A multiple sequence alignment editor is described which runs on a VAX/VMS system and can exchange data with a number of other programs, including those of the Genetics Computer Group (GCG). Up to 199 sequences can be aligned. The quality of the alignment can be easily judged during its development because the display attributes to each character are determined by the way it matches the other sequences. Four methods are available for calculating the highlighting to emphasize different aspects of the relationships of the sequences and up to four styles of highlighting can be used at the same time. Laser printer output is suitable for publication without modification.

Molecular Sequence Data↗
PubMed1991

Bechet's colitis: a differential diagnosis in inflammations of the large intestine.

A previously well 39 year old woman presented with severe localized and painful anorectal ulceration. There were no other associated symptoms apart from arthritis of the hips and fingers. In the absence of definitive tissue diagnosis, a presumptive diagnosis of Crohn's disease was made. After a period of progression, the inflammation and ulceration subsided with conservative therapy. Following a relatively symptom-free period of 7 years, painful ulceration recurred in the same segment of bowel, which was refractory to steroid therapy but responded to defunctioning of the rectum. Upon excision of the defunctioned rectum, multiple discrete ulcers developed in the remaining colon, with a fistula from the distal sigmoid colon to the midline wound. The patient simultaneously developed painful apthous ulceration of the mouth and throat, and pustules appeared on the perianal skin and trunk for the first time. A colectomy was performed, with good results. The pathology of the colonic lesions is described. The characteristic appearance of these lesions, together with associated 'major' and 'minor' clinical criteria, enabled a diagnosis of Bechet's disease to be made. Although there is some overlap, particularly in the distribution of this condition with Crohn's colitis, the pathologic appearances in Bechet's colitis are relatively distinct. A diagnosis of Bechet's colitis should not be excluded in a patient presenting with atypical inflammatory bowel disease, even if associated clinical criteria are not simultaneously present.

Adult↗
PubMed1991

The effects of comfrey derived pyrrolizidine alkaloids on rat liver.

Three groups of young adult rats were fed pyrrolizidine alkaloids derived from Russian comfrey to study the effects of the herb on the liver. Group I animals received a single dose of 200 mg/kg body wt, Group II 100 mg/kg three times a week for 3 weeks and Group III 50 mg/kg three times a week for 3 weeks. All rats showed light and electron-microscopic evidence of liver damage, the severity of which was dose dependent. There was swelling of hepatocytes and hemorrhagic necrosis of perivenular cells. There was a concomitant loss of sinusoidal lining cells with disruption of sinusoidal wall and the sinusoids were filled with cellular debris, hepatocyte organelles and red blood cells. Extravasation of red blood cells was evident. Terminal hepatic venules were narrowed by intimal proliferation, and in Group II and III, reiculin fibres radiated from these vessels. These appearances have been described in veno-occlusive disease due to pyrrolizidine alkaloids from other plant sources such as Senecio and Crotalaria. The safety of comfrey, a widely used herb, in relation to human consumption requires further investigation.

Animals↗
PubMed1990

Properties of BGP1, a poly(dG)-binding protein from chicken erythrocytes.

The chicken beta A-globin gene contains in the neighborhood of its 5' promoter a (dG)-homopolymer sequence 16 base pairs long. The 66 kD protein BGP1 (beta globin protein 1), isolated from chicken erythrocytes, has been shown to bind specifically to this sequence. We describe further purification of BGP1, measure its affinity for the beta A-globin promoter binding site, and analyze its binding properties. The minimal binding sequence is seven dG residues; methylation interference studies show that each of these residues contacts BGP1. Binding competition experiments employing (dG).(dC) oligomers of varying lengths also consistent with (dG)7 as a minimum recognition sequence. All of the data can be explained by a model in which BGP1 binds to any contiguous set of seven (dG) residues, so that the effective constant for binding to (dG)n is proportional to n minus 6. This behavior may be typical of proteins that bind specifically to repeated sequences.

Animals↗
PubMed1990

Testicular germ cell tumor with pineal metastases.

A patient with a mixed testicular germ cell tumor (choriocarcinoma, teratocarcinoma and embryonal carcinoma) that had metastasized to the lungs, cerebrum, and pineal gland is presented. The metastases had resulted in localized neurological signs and initially, on clinical grounds, a primary intracranial lesion could not be excluded. The occurrence of tumor metastases to the pineal gland is discussed and the literature is reviewed.

Adult↗
PubMed1989

Suicide by band saw.

Suicidal injuries caused by power tools have rarely been reported in the literature. The case of a 37-year-old white male schizophrenic patient who sustained a fatal self-inflicted neck injury from a band saw, while engaging in occupational therapy, is presented. Unusual features of this type of injury as noted at postmortem examination were the extent of the wound, the absence of hesitation injuries, and the presence of grease wipe, bone dust, and sawdust within the wound.

Adult↗
PubMed1989

Papillary cystadenocarcinoma of the appendiceal stump with mucocele and peritoneal metastases.

A 54-year-old Polynesian male developed a mucocele of the appendiceal stump 25 years after appendicectomy. Scattered peritoneal deposits up to 0.4 cm in diameter were also identified at laparotomy, and these were confined to the right iliac fossa. The cyst was excised with a right hemicolectomy and histology showed a mucus-producing papillary cystadenocarcinoma arising in the unburied appendiceal stump. There was invasion of the cyst wall and the peritoneal nodules contained metastatic tumour acini. The patient is well 12 months after surgery. This is a case of a rare tumour arising uniquely in an appendiceal stump and producing a mucocele. The term mucocele is discussed and recommendations made for its usage in pathological diagnosis.

Appendectomy↗
PubMed1988

An erythrocyte-specific protein that binds to the poly(dG) region of the chicken beta-globin gene promoter.

The promoter region of the chicken adult beta-globin gene contains a sequence of 16 deoxyguanosine residues located at a nucleosome boundary in tissues where the gene is inactive. In definitive erythrocytes that express the beta-globin gene, the nucleosome is displaced, the G-string and adjacent sequences are occupied by sequence-specific DNA-binding proteins, and a nuclease hypersensitive domain is generated in this region. To gain insight into the role of the G-string in this series of events, we have examined the proteins that bind to it. Using the gel mobility shift assay and a monoclonal antibody that blocks specific binding to the G-string, we have identified a specific protein, BGP1, that is found only in chicken erythroid cells and appears at the same time, or shortly before, the changes in chromatin structure. The antibody interacts strongly with BGP1 and cross-reacts weakly with Sp1. Although both BGP1 and Sp1 require Zn2+ for their DNA-binding activity, these proteins differ in their binding-site specificities, chromatographic properties, and molecular weights. In contrast to Sp1, which is found in a wide variety of cell types, BGP1 is restricted to erythrocytes and is most abundant in definitive erythrocytes. Thus, its presence corresponds to the tissue- and stage-specific occupancy of the G-string in vivo.

Animals↗
PubMedDate not supplied

Organization and sequences of the variable, joining and constant region genes of the human T-cell receptor alpha-chain.

An essential property of the immune system is its ability to generate great diversity in antibody and T-cell immune responses. The genetic and molecular mechanisms responsible for the generation of antibody diversity have been investigated during the past several years. The gene for the variable (V) region, which determines antigen specificity, is assembled when one member of each of the dispersed clusters of V gene segments, diversity (D) elements (for heavy chains only) and joining (J) segments are fused by DNA rearrangement. The cloning of the beta-chain of the T-cell antigen receptor revealed that the organization of the beta-chain locus, which is similar to that of immunoglobulin genes, is also composed of noncontiguous segments of V, D, J and constant (C) region genes. The structure of the alpha-chain seems to consist of a V and a C domain connected by a J segment. We report here that the human T-cell receptor alpha-chain gene consists of a number of noncontiguous V and J gene segments and a C region gene. The V region gene segment is interrupted by a single intron, whereas the C region contains four exons. The J segments, situated 5' of the C region gene, are dispersed over a distance of at least 35 kilobases (kb). Signal sequences, which are presumably involved in DNA recombination, are found next to the V and J gene segments.

Amino Acid Sequence↗