Mucin histochemistry of esophagus in health and malignancy

AIMS

To study mucin histochemistry of the normal esophagus, esophageal adenocarcinoma, and carcinoma exhibiting glandular and squamous elements, to ascertain the origin of these tumors.

METHODS

Mucin histochemistry was studied in sections of the normal cardioesophageal junction obtained from 25 post-mortem specimens and in 12 mucin-secreting esophageal carcinomas.

RESULTS

The normal submucosal esophageal glands and three adenocarcinomas secreted predominantly sulfomucins; a mixture of neutral and sialomucins was seen in the nine carcinomas with squamous and glandular traits. Barrett's metaplasia was not encountered.

CONCLUSIONS

In the absence of Barrett's metaplasia, esophageal adenocarcinoma probably arises from the submucosal glands, whereas squamous carcinomas with mucin-secreting component could arise from metaplastic change in squamous epithelium, cardiac glands, or multipotent stem cells in the epithelium.

Regulation of the expression of cyclin-dependent kinase inhibitor p21 by E2A and Id proteins

The helix-loop-helix transcription factor E2A plays important roles not only in promoting cellular differentiation but also in suppressing cell growth. Id proteins, the inhibitors of E2A, have opposite effects on cell differentiation and growth. To understand the mechanisms by which E2A suppresses cell growth, we examined the role of E2A in regulating the expression of the cyclin-dependent kinase inhibitor p21CIP1/WAF1/SD11, which prevents cell cycle progression upon overexpression. By using transient-cotransfection assays of luciferase reporter constructs in HeLa cells, we have found that overexpression of E2A can transcriptionally activate the p21 gene. To identify the sequences that mediate this activation in the promoter of the p21 gene, we carried out mutational analyses. Out of the eight putative E2A-binding sequences (E1 to E8) in the promoter, the E1 to E3 sequences located close to the transcription start site are found to be essential. In addition, loss of the E boxes in the promoter also reduces p21 expression without cotransfection with E2A in HIT pancreatic cells, where the endogenous E2A-like activity is high. Furthermore, we have also shown that overexpression of E2A in 293T cells activates expression of the endogenous p21 gene at both the levels of mRNA and protein. In correlation with the finding that E47 overexpression leads to growth arrest in NIH 3T3 cells, we have shown that Id1 overexpression in NIH 3T3 cells accelerates cell growth and inhibits p21 expression. Taken together, these results provide insight into the mechanisms by which E2A and Id proteins control cell growth.

Cooperating events in lymphomagenesis mediated by feline leukemia virus

Feline leukemia virus (FeLV)-mediated lymphomagenesis in the domestic cat has been examined as a model of lymphoid malignancy in a naturally outbreeding population. The pathogenesis of two distinct, naturally occurring types of FeLV-induced tumors has been investigated: (1) a thymic lymphoma of T-cell origin, typical of FeLV-induced lymphoma, and (2) an extrathymic, extranodal lymphoma of non-B non-T-cell origin. The genetic features of these tumors are clearly distinguishable, and include determinants encoded both by the virus and the host. Virally encoded determinants of pathogenesis include the long terminal repeat (LTR) and the envelope SU protein. Cellular determinants include the involvement of a set of proto-oncogenes, and other factors characteristic of the specific cell type of origin of the tumor. Functional studies are aimed at evaluating the action and interaction of these genetic determinants in the pathogenesis of lymphoma in an animal model system.

Effect of glucocorticoids on neonatal rabbit renal cortical sodium-inorganic phosphate messenger RNA and protein abundance

Administration of glucocorticoids to neonates increases proximal tubule volume absorption by increasing glucose, bicarbonate, and amino acid transport. We have recently demonstrated that glucocorticoids may contribute to the maturational decrease in phosphate transport. This study examines the maturation of NaPi-6 [the regulated proximal tubule sodium-inorganic phosphate (Na-Pi) transporter] mRNA and protein abundance and the mechanism for the decrease in phosphate transport by glucocorticoids. Weaned young rabbits (5 wk) had a 2-fold greater brush border membrane NaPi-6 protein abundance than that measured in adults. Renal cortical NaPi-6 mRNA abundance was comparable in neonates (less than 10 d of age) and adults. Renal brush border membrane vesicles from dexamethasone-treated neonatal rabbits (10 micrograms/100 g of body weight for 4 d) had a lower rate of Na-Pi transport than vehicle-treated controls (46.8 +/- 6.5 versus 71.0 +/- 9.0 pmol 32P/10 s/mg of protein, p < 0.05). Abundance of NaPi-6 protein in brush border membrane vesicles was 3-fold lower in newborn rabbits treated with pharmacologic doses of dexamethasone than in vehicle-treated controls. NaPi-6 mRNA abundance was the same in both groups. NaPi-1, a brush border membrane phosphate transporter which is also an anion channel, mRNA, and protein abundance was not affected by glucocorticoids. These data demonstrate that there is a maturational decrease in NaPi-6 protein abundance and that glucocorticoids decrease neonatal phosphate transport, at least in part, by reducing the number of Na-Pi transporters.

Preliminary evaluation of safety aspects of neem oil in kerosene lamp

Kerosene lamps containing one per cent neem oil were used for mosquito repellent action in a village near Delhi. The safety aspects of this personal protection method developed by Malaria Research Centre were evaluated by animal studies and clinical examination of population before and after exposure. Single application of neem oil (1%) did not produce skin irritation in rabbits and adverse effect on guinea pigs after exposure to aerosol. Clinical examination of 156 adults and 110 children did not reveal any major adverse effects after one year of exposure to 1% neem oil.

Primary sequence and evolutionary conservation of ribosomal protein genes from the domestic cat

Ribosomal proteins complex with ribosomal RNA to form the subunits of the ribosome, and as such, serve essential functions in protein synthesis. Accumulating evidence suggests that ribosomal proteins are bifunctional molecules with roles in diverse cellular processes in addition to protein synthesis. Previous studies have demonstrated that expression of four ribosomal proteins. L41, S3a, S4, and S17, is elevated in malignant lymphomas of the domestic cat. Reported here is the nucleotide sequence of cDNA clones encoding feline ribosomal proteins L41, S3a, S4, and S17.

Genetic determinants of feline leukemia virus-induced multicentric lymphomas

Three discrete forms of feline leukemia virus (FeLV)-associated lymphoma have been described clinically: (1) thymic, (2) alimentary, and (3) multicentric. The most common and best-characterized lymphomas are of T-cell origin, generally occurring in the thymus. These tumors typically contain mature T-cells, involve the activation of a distinctive set of proto-oncogenes, and contain FeLV proviruses whose long terminal repeat (LTR) sequences contain tandemly repeated enhancers. Previous studies of a small group of extrathymic, multicentric lymphomas implicated a different set of genetic determinants. The present study expands those observations by examining the lineage of origin, the involvement of proto-oncogenes, and the structure of LTR and env gene sequences in a set of 11 natural, extrathymic lymphomas of the multicentric type. A pattern of genetic events associated with FeLV-positive multicentric lymphomas emerges from this analysis that is clearly distinct from the pattern associated with thymic lymphomas. The tumors do not contain T-cells or B-cells, as evidenced by the germ line organization of TCR beta and IgH loci. Proto-oncogenes strongly implicated in T-cell lymphomagenesis are not involved in these tumors. Rather, a distinct set of proto-oncogenes may be involved. Most striking is the repeated occurrence of an FeLV isolate whose LTR and env gene bear unique sequence elements.

Compression of the C-2 root by a rare anomalous ectatic vertebral artery. Case report

The authors report a symptomatic congenitally anomalous ectatic vertebral artery not passing through the transverse foramen of the atlas (C-1), but instead piercing the dura mater below the posterior arch of the C-1 in the atlantoaxial (C1-2) interlaminar space. This occurrence is exceptionally rare, but in this case it was uniquely associated with occipital neuralgia due to vascular compression of the C-2 root. Microvascular decompression was curative. Neuroradiological and surgical findings are presented and their implications discussed.

Reversal of Hartmann's procedure: timing and operative technique

A review of closure of Hartmann's colostomy was undertaken to establish guidelines for the timing and technique of reversal. Between 1984 and 1990 there were 69 reversals; 48 patients originally had diverticular disease and 21 had carcinoma. One-third underwent reversal before 4 months and two-thirds after this time. The operative mortality rate was 3 per cent and the anastomotic leak rate 4 per cent. Significant morbidity occurred in 30 per cent. There was no advantage in delayed closure. Complications occurred in 24 per cent of patients undergoing reversal before and 35 per cent undergoing reversal after 4 months. Thirty-five anastomoses were hand-sewn and 34 stapled. There were no differences in operating time for the two techniques, but a greater number were stapled after 4 months than before (P less than 0.05), which may reflect increased rectal stump shrinkage with time. There were no differences in complication rates whether the anastomosis was hand-sewn (34 per cent) or stapled (26 per cent). Closure of Hartmann's colostomy is a safe procedure but has a significant morbidity in nearly one-third of cases. On the basis of these results, there is no indication to delay closure after 4 months have elapsed, and earlier reversal, when the rectal stump is most accessible, is recommended.

Influence of clonidine, methyldopa and propranolol on acute toxicity of fenitrothion in mice

The effect of pretreatment with clonidine, methyldopa and propranolol, and of atropine was studied in mice on acute toxicity of fenitrothion, the active ingredient of TIK-20. Atropine significantly decreased and propranolol somewhat decreased the fenitrothion induced death in mice. Clonidine and methyldopa somewhat increased the percentage mortality due to fenitrothion.

Wandering distal ends of ventriculo-peritoneal shunts

Spontaneous migration with extrusion of the distal catheter is an unusual complication of ventriculo-peritoneal shunt for hydrocephalus. Four instances of disconnection migration are reported: one into a patent processus vaginalis and three extruding per rectum.

Postcatheterization urethral strictures following cardiac surgery in children

Ten children among 221 with congenital cardiac anomalies developed urinary symptoms after removal of urethral catheters, which were routinely inserted for monitoring purposes during and after cardiac surgery. Six children developed urethral strictures. Poor tissue perfusion concomitant with serious congenital cardiac anomalies, together with secondary urine infection in the presence of a urethral catheter, are proposed as significant factors in the causation of such strictures in children undergoing cardiac surgery.

Action of acetylcholine on the atropinised heart of the frog during summer months

During summer months high doses of acetylcholine produced positive inotropic and chronotropic actions in 19 out of 22 preparations of atropinised perfused heart of the frog. Hexamethonium failed to block both the positive inotropic and chronotropic actions of Ach. Interestingly another ganglion blocking agent mecamylamine as well as beta adrenergic blocking agent propranolol blocked the positive inotropic action but not the positive chronotropic action.

The effect of drugs on stress-induced changes of myocardial glycogen and blood glucose concentration in rats

Rats that were subjected to restraint stress for 18 h were found to have reduced myocardial glycogen and blood sugar levels and showed histological changes in heart and adrenals. The effects of alpha-methyl-p-tyrosine, alpha-methyl-dopa, disulfiram and actinomycin D on these stress-induced changes were examined. Of these drugs, only alpha-methyl-p-tyrosine was able to prevent the fall in myocardial glycogen and blood sugar and none of the drugs prevented the histological changes induced by stress.