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Biomedical subjects

P K Basu

Publications and source records attributed to P K Basu.

At least 127 records · Page 7Linked to original sources
PubMed1978

Laser iridotomy and trabeculotomy in monkeys. A morphological study.

We performed laser iridotomy and trabeculotomy on Rhesus and Cynomologous monkeys with a Britt Model 152 repetitively pulsed argon laser. The total energy delivered varied from 2 to 6 joules. The easiest sites for laser iridotomy were at 3 and 9 o'clock. The iridotomy remained open for at least 2 months. Scanning electron microscopy confirmed that no damage occurred to the lens. After laser burns to the trabecular meshwork light microscopy showed anterior synechiae, corneal endothelial swelling and trabecular coagulation. Scanning electron microscopy showed that only a few holes were made in the trabecular tissue, even after a massive dose; some of them appeared to lead directly to the canal of Schlemm. We feel that although this machine can be used successfully to perform iridotomy in humans, it cannot replace the current surgical procedures in glaucoma.

Animals↗
PubMed1978

The effect of cigarette smoke on the human tear film.

We used a corneal microscope to measure the break up time of the tear film (BUT) in 14 young volunteers; four were men and all were non-smokers. Values under controlled conditions and after ten minutes of exposure to filtered air or to cigarette smoke in a room of 14.6 m3 were determined. Exposure to cigarette smoke was associated with a substantial (35--40%) and statistically significant (P less than 0.001) reduction of BUT. This may reflect an alteration in the relative proportions of the three constituents of the tear film. The chemical responsible, and the way in which it increases the flow of watery constituents and suppresses mucus and lipid secretion demand further research.

Adult↗
PubMed1978

Can steroid reduce endothelial damage in stored corneas? Effect on cell viability and ultrastructure.

We studied the effect of steroid on the viability and integrity of the endothelium of variously stored corneas of different species of animals and man. Paired corneas of rodents and humans were used,--one cornea (experimental) being treated with steroid and the other (control) not. Rat and guinea pig corneas were kept at 37 degrees C for one hour in phosphate buffered saline with or without hydrocortisone 21-sodium succinate (10-6M). Human corneas were kept at 4 degrees C for 4 days in M-K medium with or without hydrocortisone 21-sodium succinate (10-6M). The viability of the endothelia (rat and guinea pig) was tested with para Nitro Blue Tetrazolium and trypan blue dye exclusion tests. The ultrastructural changes in the control and experimental endothelial (guinea pig and human) were examined by scanning electron microscopy. Viable cells P less than 0.001) were more numerous and ultrastructural alteration less in the endothelia of the steroid treated corneas compared to the controls.

Animals↗
PubMed1977

The systemic production of cytotoxic lymphoid cells in corneal allograft reaction. 1. A quantitantitative study utilizing 51chromium release assay.

The purpose of the study was to determine whether the mechanism of corneal allograft rejection is systemic in nature. Utilizing a 51Cr release assay in which labelled donor and recipient corneal cells were used as targets, it was demonstrated that cytotoxic cells specific for antigens located in donor corneal cells were present in spleen and lymph nodes.

Animals↗
PubMed1977

The prevention of autolysis in stored corneas by lysosome stabilization. A histochemical study.

We wished to determine if dexamethasome, acting as a lysosome stabilizer, could reduce the release and activation of the lysosomal acid hydrolases, and thus retard autolysis of stored corneas. One cornea (experimental) of a rabbit was soaked in a 2 per cent steroid solution and the other cornea (control) in physiological saline for 3 hours at 23 degrees C. The experimental and control corneas were then processed histochemically to show the localization of the lysosomal marker enzymes beta-glucuronidase and acid phosphatase. Compared to the controls the steroid treated corneas showed reduced enzyme activity suggesting that autolysis during storage had been retarded.

Acid Phosphatase↗
PubMed1977

Systemic sensitization of corneal allograft recipients before the clinical onset of graft reaction.

We wished to know if full-thickness corneal allografts placed centrally in clear host corneas would cause systemic sensitization. Keratoplasty was done in 13 rabbits and a leucocyte migration inhibition test was done on their systemic blood five to seven days operation using donor specific corneal antigen. All but two animals had positive results (mean inhibition 27% "/- 2.2) showing that, following keratoplasty, systemic sensitization does occur. Absence of blood vessels and lymphatics thus does not constitute an absolute barrier to sensitization of the recipient.

Animals↗
PubMed1977

Factors in the survival of stored corneas.

In studying the survival of stored corneas we wished to know if excising the cornea was the most critical step or if one storage medium was superior to another. Rabbit corneas were excised and stored in various media at 4 degrees C or 23 degrees C for four days. The storage media included M-K medium, balanced salt solution (BSS) and 10(-8)M concentration of hydrocortisone in M-K medium and BSS. Comparisons were made by measuring acid phosphatase as an index of autolysis. Results showed a reduced amount of autolysis at 4 degrees C as compared to 23 degrees C. No statistical difference between M-K medium and BSS was seen but steroid decreased autolysis. M-K medium plus hydrocortisone seemed to be the best of the solutions studied, but removal of the cornea seemed to be the most important factor in its survival.

Acid Phosphatase↗
PubMed1977

The presence of cell-mediated immunity in uveitis.

We have attempted to demonstrate cell mediated immunity in cases of uveitis. We tested blood samples of patients for leucocyte migration inhibition (LMI) and lymphocyte transformation (LT). The gel diffusion test was used to detect humoral antibody. Allogeneic uveal, retinal and corneal antigens were prepared for the tests from eye bank eyes. The LMI and LT tests gave positive results in 9 out of 16 cases. In these 9 cases 8 were positive to retinal antigen, three with corneal antigen and only one was positive against uveal antigen. Humoral antibodies were not detected. We suggest that cell mediated autoimmunity is present but the relationship of this to the uveitis itself is obscure.

Adolescent↗
PubMed1977

Tensile strength of fascia lata sutures following gamma radiation.

Gamma radiation (Co-60) is used to sterilize biological sutures. We wished to compare the effect of gamma-radiation in doses of 2.7 and 4.0 Mrads on the tensile strength of human fascia lata sutures obtained from the same cadaver. Five variables of tensile strength viz. Breaking Elongation, Breaking Load, Yield Point Load, Work of Rupture and Elastic Stiffness were determined for each suture. For Breaking Elongation the mean strength for the 4.0 Mrad dose was 3% less than for 2.7 Mrad dose (P less than 0.05); for Breaking Load 11% less (P less than 0.01); for Yield Point Load 9% less (P less than 0.02); for Work of Rupture 14% less (P less than 0.01); and for Elastic Stiffness 8% less (P less than 0.02). Irradiation with 4.0 Mrads, does not greatly change the tensile strength characteristics of fascia lata sutures.

Adult↗
PubMed1977

Ultimate tensile strength of gamma irradiated human scleral sutures.

Scleral sutures were prepared by hand from the equatorial region of 53 paired donor eyes. The weakening produced by two doses of gamma Co-60 radiation (2.7 and 4.0 Mrads) was compared using measurements of tensile strength; the strength of unirradiated scleral sutures was also measured, for comparison. The three variables of tensile strength, viz. Breaking Elongation, Breaking Load, and Work of Rupture was determined for each suture. As compared to unirradiated sutures, Breaking Elongation decreased on irradiation (P less than 0.01), but the two doses of irradiation were not statistically significant (P greater than 0.05); Breaking Load increased on irradiation (P less than 0.01), but the two doses of irradiation were again not significant (P greater than 0.05). Only 4.0 Mrads irradiated scleral sutures, as compared to unirradiated ones, showed a statistically significant reduction (P less than 0.01) for Work of Rupture. No definite relationships were found by regression analysis among the tensile strength variables and the independent variables of sex and various storage times for the 4.0 Mrad data. Work of Rupture showed a negative relationship to the age of donors, though the change with age was small.

Dose-Response Relationship, Radiation↗
PubMed1976

The detection of immunologically competent cells in corneas showing an immune reaction - a simplified technique -.

We wished to devise a simple in vitro test for identifying the presence of antigen sensitive lymphocytes in corneal tissue having an immunological inflammatory reaction. A number of rabbits were immunized by subcutaneous injections of human serum albumin (HSA). A final injection of the same antigen was given in the centre of the cornea to produce an immunological corneal inflammation. Other rabbits were immunized by an antigen unrelated to HSA. A non-immunological corneal inflammation was produced in another group of animals by applying sodium hydroxide. Five days after the immunogenic and non-immunogenic corneal insults, when the limbus showed vascularization, the eyes of the different groups of animals were enucleated. From each eye, small corneal discs containing a portion of the limbus were cut with a trephine. The discs (explants) were then incubated for 20-24 hours at 37 degrees C in the presence or absence of HSA or in the presence of an antigen unrelated to HSA. At the end of incubation, the extent of leucocyte migration from each explant was measured. Only in the presence of the specific antigen did leucocytes from explants of the immunized animals show marked inhibition of migration.

Antigen-Antibody Reactions↗
PubMed1976

Chemotactic migration of leucocytes through corneal layers: an in vitro study.

The ability of polymorphonuclear leucocytes (PMNs) to migrate into the different corneal layers in the presence or absence of a chemotactic stimulus was investigated in rabbits. The epithelial and/or endothelial surfaces were damaged in some corneas and in others they were intact. One side of the cornea was kept in contact with a viable population of rabbit PMNs and the other side with a chemotactic agent (zymosan activated human serum). The migration of PMNs into the cornea was traced histologically. The PMNs could not penetrate intact epithelium and Descemet's membrane even under the influence of a chemotactic stimulus. The stroma allowed PMN migration only when the chemotactic agent was present. The endothelium offered no resistance to PMN invasion whether the chemotactic stimulus was present or not.

Animals↗
PubMed1975

Histochemical localization of hydrolytic enzymes during corneal graft reaction.

We studied hydrolytic enzymes in the graft bed during the corneal graft reaction. Two enzymes, beta-glucuronidase and acid phosphatase, were used as the markers of lysosomal hydrolytic enzymes. These were traced histochemically at various times before and after the onset of the graft reaction in a corneal xenograft model. Results showed a relationship between the degree of graft opacity, cellular infiltration and enzyme localization. It appeared that during the early stages of graft reaction, the granulocytes, and during the late stages, the agranulocytes were the main source of the enzymes.

Acid Phosphatase↗
PubMed1975

Role of lysosomal constituents of neutrophils in corneal graft reaction.

Band 2 protein exists in a firmly bound state in lysosomes, and is released when the cells concerned are specifically stimulated. The necessary stimulus can originate from different kinds of immunogenic interactions. The objective of this study was to determine whether during corneal graft reaction Band 2 protein could be detected in the host's cornea and aqueous humour. Band 2 protein was detected in the reacting host corneas (8 out of 23 eyes) and the aqueous humours (2 out of 23 eyes), mainly during the second and third postoperative weeks when parallel histological studies showed an accumulation of neutrophils in the graft bed. The severity of graft reaction appeared to run parallel to the amount of free Band 2 protein in the host cornea. After this period, in spite of the presence of a large number of neutrophils in the reacting host cornea, Band 2 protein was hardly detectable. This study indicates that the necessary stimulus for the secretion of Band 2 protein from rabbit neutrophils is present in the early stages of corneal xenograft reaction. The presence of the protein in the host cornea may be a factor in the development of the vascular response associated with the corneal graft reaction.

Animals↗
PubMed1975

The prevention of autolysis of stored cornea using steroid as a lysosome membrane stabilizer.

Many eyes donated for use in corneal grafting are rejected because of signs of autolysis in the donor material. The purpose of this experimental study was to determine whether hydrocortisone acting as a lysosome membrane stabilizer could prevent or retard autolysis of the corneas under storage, and if so, what was the most efficacious concentration. Different groups of rabbit corneas were placed in saline as controls or in varying concentrations of hydrocortisone (10(-10) M to 10(-4) M at pH 7.4) at 37 degrees C and 4 degrees C. Acid phosphatase released after six hours was measured biochemically. This enzyme was used as a marker enzyme reflecting lysosomal labilization. Results showed a significant stabilization of the lysosomal membrane at 4 degrees C as compared to 37 degrees C. A trend towards stabilization of the lysosomal membrane was seen when 10(-8) M concentration of hydrocortisone at 37 degrees C was used, there being no demonstrable stabilization at 4 degrees C.

Acid Phosphatase↗