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Biomedical subjects

P J Gardner

Publications and source records attributed to P J Gardner.

At least 19 recordsLinked to original sources
PubMed2004

Use of dimensionless residence time to study variations in breakthrough behaviour in expanded beds formed from varied particle size distributions.

This work demonstrates an experimental method for studying breakthrough behaviour in expanded beds. The behaviour of beds made with differently sized particles were studied at varying flowrates. The use of a dimensionless residence time measurement allowed a more valid comparison of breakthrough characteristics in expanded bed operation by compensating for the changes in bed volume that occur during expansion. We demonstrate that bed breakthrough behaviour can be compared directly even when the beds contain different-sized particles and hence have different expanded volumes. By utilising this concept we demonstrate that, in the case of the Alcohol Dehydrogenase (ADH) / STREAMLINE Phenyl system used here, there was little or no variation in ADH breakthrough behaviour between beds of differently sized particles operating at flowrates above 100 cm/h. This suggests that the higher specific surface area and hence binding capacity of smaller particles is negated in this case due to mass transfer limitations and the increase in system void volume even at normal operating flowrates of 200-300 cm/h.

Algorithms↗
PubMed1984

The absence of premalignant changes in the cryptorchid testis before adulthood.

Previous investigators have reported that premalignant changes in the form of abnormal germ cells can be detected in the cryptorchid and infertile adult testis. These cells are characterized by a thin rim of pale-staining cytoplasm, a large hyperchromatic nucleus and prominent nucleoli. We studied 113 biopsies from 102 patients to determine if these abnormal germ cells occur in the nonadult cryptorchid testis. The patients ranged in age from 3 months to 16 years. Evaluation of testicular tissue by light microscopy disclosed histological alterations in the undescended testis, which were those commonly ascribed to the undescended testis. However, none of the changes could be interpreted as premalignant. The abnormal germ cells described by other investigators were not found in any of these specimens.

Adolescent↗
PubMed1983

Immunocytochemical staining of isolated rat Sertoli cells for anti-FSH beta.

Sertoli cells are a primary target for the action of follicle-stimulating hormone (FSH) in the testis. The purpose of this investigation was to verify ultrastructurally that FSH binds to receptors on the plasma membrane of isolated rat Sertoli cells. A relatively pure aliquot of Sertoli cells was obtained by first dissociating testicular tissue from immature rats with collagenase and then centrifuging the suspension in Percoll density gradients. Pre-embedding staining with the peroxidase anti-peroxidase (PAP) complex technique using anti-FSH beta as the primary antiserum localized endogenous receptor-bound FSH on the plasma membrane of isolated Sertoli cells. Staining was considered to be specific since membranes of Sertoli cells derived from hypophysectomized rats were not stained when subjected to the same procedure. Cytoplasmic vesicles in Sertoli cells from experimental, control, and hypophysectomized groups also stained with PAP. Staining of these structures appeared to be specific since it was obliterated by preabsorption of anti-FSH beta with FSH. Preabsorption with luteinizing hormone (LH) did not affect the staining of cytoplasmic vesicles. The results of this investigation provide the first evidence for ultrastructural localization of specific binding sites for anti-FSH beta on the cell membrane of isolated Sertoli cells using an unlabeled antibody technique, and they further support the contention that Sertoli cells are a primary target for the action of FSH.

Animals↗
PubMed1983

Ureteral reaction to suture material.

Dog ureters were anastomosed end to end using either chromic catgut, polyglycolic acid (PGA), polyglactin-910, or polypropylene sutures. Analysis of luminal diameters, fibrosis, scar vascularity, and inflammatory reaction four and seven months later indicated that in ureters of the uninfected dog the best results were obtained with polyglycolic acid. Ureters anastomosed with catgut gave results that were slightly less acceptable.

Animals↗
PubMed1979

The effect of neonatal thymectomy on the induction of autoimmune orchitis in rats.

The objective of these experiments was to determine the effects of neonatal thymectomy on the induction of experimental autoimmune orchitis in inbred rats of the Fischer 344 and Lewis strains. It was found that thymectomy alone in Lewis rats, and thymectomy followed by immunization with testicular extract in both Lewis and Fischer 344 rats, led to the development of autoimmune orchitis, as indicated by decreased testes weights, increased serum spermagglutinating antibody titers and histopathological changes in the testes. These data indicate that rats of the Lewis strain are genetically predisposed to the development of autoimmune orchitis, and thymectomy alone leads to active manifestations of the disease, which are further enhanced by subsequent immunization with testicular extract. In Fischer 344 rats, thymectomy followed by immunization leads to indications of early signs of experimental autoimmune orchitis. This is in contrast to experimentally induced autoimmune diseases in other model systems, where previous investigators have reported that thymectomy lessens or prevents induction of autoimmune disease. It is suggested that these differences may be related to the timing of thymectomy with regard to differences in the time of appearance of sperm antigens (at puberty) as compared to pre-natal and early neonatal appearances of other autoantigens.

Animals↗
PubMed1979

Considerations for establishing the validity of immunocytological studies.

Immunocytology has wide spread applications for localizing tissue antigens, as evidenced by the recent exploitation of this technique in biological studies. Documenting the immunological specificity of the staining reaction is one of the most important technical considerations in validating the accrued data in immunocytological studies. The purpose of this report is to discuss and emphasize the need for conducting physiological studies in addition to the traditional immunological method and specificity controls. The ability of antibodies to bind molecules other than those molecules used as the immunizing material is a well documented fact. Hypothetically, preabsorption of the primary antibody with its specific antigen, could reduce subsequent binding of this antibody to a cross reactive tissue antigen, thus providing false confirmation of staining validity. The results of our experience with a cross reacting system in addition to other previously reported examples are discussed.

Animals↗
PubMed1978

Subcellular localization of gonadotropins and testosterone in the developing fetal rat testis.

Gonadotropins and testosterone were immunocytochemically localized in the fetal rat testes 16-18 days of gestation with the unlabeled antibody-peroxidase anti-peroxidase complex technique. Maximum staining for gonadotropins with antiserum to the beta chain of human chorionic gonadotropin (anti-hCGbeta) occurred at 16 days gestation in the seminferous tubule and 17 days gestation in interstitial (Leydig) cells. Anti hCGbeta sites were on the plasma membranes at the luminal aspects of Sertoli cells at 16 days gestation. In addition, intracellular hCGbeta sites were evident including the nucleus, nucleolus, ribosomes, some vesicles, lysosomes and centrioles. The stain for hCGbeta disappeared rapidly and by 17 days was limited to patches in the cytoplasm and nuclei. In the fetal testes, staining for anti-testosterone binding sites was most intense at 18 days of gestation either in lipid droplets or on nuclei of Leydig and Sertoli cells. Very little testosterone stain was observed before 18 days of gestation. These findings agree with physiologic data that suggest that gonadotropins bind to receptors and stimulate testicular development and the capacity for testosterone production.

Animals↗
PubMed1977

Polyglactin 910 suture in urinary tract.

Cystotomies in guinea pigs and ureteral anastomoses in dogs were sutured with polyglactin 910. Silk and chromic catgut were used as control sutures in the bladders and chromic catgut in the ureters. Three months postoperatively in bladders sutured with polyglactin 910 small epithelial cysts were noted, which increased in size with time. In ureters sutured with polyglactin 910 cystic diverticula were observed eight months postoperatively. Because of the difference of tissue reaction to polyglactin 910 compared with catgut, further long-term studies are urged in different species of animals, prior to the clinical use of polyglactin 910 in the urinary tract.

Animals↗
PubMed1977

Immunocytochemical localization of a folicle stimulating hormone-like molecule in the testis.

A follicle-stimulating hormone (FSH)-like molecule was localized in normal adult rat testes as well as testosterone-treated hypophysectomized rat tests with an unlabeled antibody (anti-FSH), peroxidase-antiperoxidase complex technique. Anti-FSH bound specifically to ultrathin sections of acrosomes of spermatids and intranuclear bodies of early spermatids. Quantitation of staining intensity demonstrated that FSH, used as an absorbing antigen, would significantly reduce this binding. There was less anti-FSH binding to the acrosomes of spermatozoa in the body and tail of the epididymis as compared to the less mature germ cells located in the testis and head of the epididymis. The acrosomal and nuclear staining of spermatids taken from hypophysectomized animals was similar to staining observed in sham injected animals. Taken together, these results suggest that there is a molecule within the acrosome that is immunologically similar to FSH. Most importantly, these results emphasize the importance of conducting physiologic experiments in conjunction with immunocytochemical studies.

Animals↗
PubMed1977

An autoradiographic study of smooth muscle hyperplasia in the swine ureter.

Autoradiographs of healing ureteral defects demonstrated significant uptake of tritiated thymidine in pigs sacrificed during the first 2 weeks after ureterotomy. The earliest and most heavily labeled tissue was epithelium followed by proliferation of subepithelial connective tissues and smooth muscle of the muscularis. The labeling of significant numbers of myocytes within the muscularis was indicative of smooth muscle replacement by hyperplastic means. The fact that most mitotically active smooth muscle cells were seen in the muscle remnant adjacent to wound margins suggests this as the primary source for new muscle.

Animals↗
PubMed1976

Enthalphy changes associated with the denaturation of collagens of different imino acid content.

The enthalpy changes associated with the denaturation of acid-soluble and insoluble collagens prepared from sheep, cod, halibut and pike skin were determined by differential scanning calorimetry. The enthalpy change associated with the soluble collagens decreased with decreasing imino acid content (from 1420 cal/mol for sheep to 736 cal/mol for cod) while the value for insoluble collagens was approximately constant at 1360 cal/mol. A possible explanation for these values in terms of the nautre of the bonds present in collagen is discussed.

Collagen↗
PubMed1976

Changes in testis of guinea pig after vasectomy.

Thirty adult guinea pigs were bilaterally vasectomized and subsequently sacrificed at one, three, and six months after operation. Cell counts were performed on five seminiferous tubules from each animal to identify and quantitate changes in spermatogenesis. Forty-three per cent of the animals had alterations in spermatogenesis that were characterized by generalized hypospermatogenesis and presence of multinucleated spermatids. There was a high incidence (93 per cent) of sperm-agglutinating antibodies in the vasectomized group. Sperm antibodies were not detected in the normal and sham-operated animals. Mean testicular weights and seminiferous tubule diameters were significantly reduced in the hypospermatogenic animals. The intersitial tissue of the vasectomized and sham-operated animals was morphologically indistinguishable from that of unoperated animals.

Animals↗
PubMed1976

Long term tissue responses to catgut and collagen sutures.

Reaction of catgut and collagen sutures in both wounded and nonwounded bladder, kidney, muscle, and liver tissue was studied in guinea pigs up to 130 days after implantation. A minimal amount of degradation of ths so-called absorbable sutures was observed. There was little difference in absorption rates in the tissues studied although there seemed to be slightly greater absorption in the kidney than in other tissues. Tissue responses were characterized by the formation of a bilaminar connective tissue capsule. The inner zone contained primarily fibroblasts and histiocytes, while lymphocytes, neutrophils, and eosinophils were scattered throughout both layers. Multinucleated giant cells were often observed in the inner layer, and aggregates of lymphocytes and mast cells were occasionally found in the pericapsular areas. Calculi formed on those suture loops that were loosely tied and thus projected into the bladder lumen.

Absorption↗
PubMed1976

Smooth muscle regeneration in swine ureters: a light and electron microscopic study.

Intubated ureterotomies were performed on 16 juvenile pigs. The animals were killed at intervals of from 2 to 91 days after operation and tissue sections examined with light and electron microscopes. Ureteral wall replacement occurred within the 3 months after operation and included all tissue layers. Epithelialization of the wound surfaces occurred in the 1st week and was accompanied by a connective proliferation. Smooth muscle bridged the defect within 5 weeks and the margins of the muscularis were thickened and cellular in early stages; cells were elongated and extended towards the defect from the muscular remnant. Primitive smooth muscle cells were present at defect margins. This evidence indicates that smooth muscle was replaced by hyperplasia.

Animals↗
PubMed1975

Ultrastructural study of the neural fat-body system in the cockroach Periplaneta americana.

The neural fat-body system of the ventral nerve cord in the cockroach Periplaneta americana was studied with the light and electron microscopes. This adipose tissue surrounds the connectives and extends over the ganglia. The adipose cells typically contain numerous extremely large lipid inclusions, pleomorphic lysosomes, and tightly packed glycogen granules. The neural lamella consists of a thick inner layer rich in collagen fibers and a thin outer layer of granular material. At points where the fat body is attenuated, this granular layer is split and the outer lamina is reflected superficially to ensheath and apparently to anchor the fat body.

Adipose Tissue↗