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Biomedical subjects

O Reid

Publications and source records attributed to O Reid.

15 recordsLinked to original sources
PubMed2005

Comparison of the potential acuity meter and the visometer in cataract patients.

PURPOSE: To compare the Guyton-Minkowski Potential Acuity Meter (PAM) and the Haag-Streit Lotmar Visometer (Visometer) in their ability to predict postoperative best corrected visual acuity (BCVA) in cataract surgery. SETTING: University of British Columbia/Vancouver General Hospital Eye Care Center, Vancouver, British Columbia, Canada. METHODS: In total, 292 eyes (223 patients) of subjects with cataracts and no known macular or optic nerve pathology were recruited over 6 months. Preoperative predictions of postoperative BCVA were compared with actual postoperative BCVA. The usefulness of these instruments as a 'diagnostic test' for predicting true surgical success (defined as postoperative BCVA of 20/40 or better) from predicted surgical success (PAM or Visometer predicted acuity 20/40 or better) was analysed. RESULTS: Neither the PAM nor the Visometer predictions were statistically significant predictors of postoperative BCVA. The sensitivities of PAM and Visometer for predicting surgical success were 84.7% and 96.1%, respectively. The specificity of the PAM and Visometer for predicting surgical success was 27.3% and 9.1%, respectively. Overall, 92.7% of patients had 'successful surgery'. Given a predicted success from the PAM or Visometer the post-test probability of success was 93.5% and 93.1%, respectively. Given a predicted failure from the PAM or Visometer there was a post-test probability of surgical success of 87.5% and 84.6%, respectively. CONCLUSION: We found no clinical benefit to support using the PAM or Visometer in the preoperative assessment of cataract patients with no known retinal or optic nerve pathology.

Adult↗
PubMed2000

Degenerated tubules in the guinea pig testis after long-term vasectomy or sham operation.

The testes of eight unilaterally vasectomized and six sham-operated Dunkin Hartley guinea pigs were examined 3 years after operation by wax and resin histology and transmission electron microscopy. Degenerated tubules are reported that were common on the side of vasectomy but also found in the contralateral testes and in the controls. A central accumulation of macrophages, rich in phagocytosed debris including spermatozoal fragments, was surrounded by attenuated Sertoli cells, a markedly thickened basement membrane and myoid cells. At some sites macrophages impinged directly on the basement membrane. They probably represented highly degenerated seminiferous tubules. The study suggests that the response to injury of seminiferous tubules may show species variations. Macrophages did not feature in the degenerated seminiferous tubules we reported following vasectomy in the rat. However, the rat showed striking changes in the morphology of the basal laminae and myoid cells which did not occur in the guinea pig. Pathological changes have been reported in the human testis following vasectomy but their etiology is unclear. Studies in the guinea pig are enhancing understanding of the mechanisms and features of testicular damage.

Animals↗
PubMed2000

Effect of vasectomy on the seminiferous tubule boundary zone in the Albino Swiss rat.

The boundary zone of a seminiferous tubule consists of the basement membrane of the seminiferous epithelium, its myoid cells, and their basal laminae. This study examines the boundary zones of seminiferous tubules in healthy and degenerated testes following long-term, left-sided vasectomy in the rat and compares them to those of sham-operated controls and adult rats exposed in utero to the antiandrogen, flutamide. Degenerated tubular profiles showed similar changes, irrespective of whether the degeneration was ipsilateral or bilateral. In transverse tubular profiles, the basal laminae of the seminiferous epithelium and the myoid cells became more undulating, that of seminiferous epithelium showing complex folding. The collagen layer of the boundary zone, which lies between the basal laminae of the seminiferous epithelium and the myoid cells, thickened and its fibers became irregularly orientated. Rather than being flattened as in controls, the region of the myoid cell near the nucleus and the nucleus itself developed triangular profiles in the transversely sectioned tubules. Similar features were also seen in the degenerated tubules of rats exposed to flutamide. The changes in the boundary zone are not specific for vasectomy and probably reflect reduction in the cross-sectional area of tubular profiles and possibly in their length. We also noted occasional leukocytes infiltrating the boundary zone; they may have increased in number in those tubules that showed degeneration following vasectomy.

Androgen Antagonists↗
PubMed1999

Effect of long-term vasectomy on seminiferous tubules in the guinea pig.

The little previous work on the influence of vasectomy on the guinea pig testis has given controversial results. One group reports that the guinea pig suffers autoimmune orchitis while others claim damage may be mechanical. To clarify the issue, this study compares the morphology of seminiferous tubules 3 years after left unilateral vasectomy (8 guinea pigs) and control sham operation (6 animals). Grossly, left and right testes following left-sided vasectomy were similar to controls and not significantly different in weight. On histology, left and right experimental testes and the control material showed various degrees of seminiferous tubular degeneration, including intraepithelial vesicle formation, loss of germ cells and intraluminal macrophages. Although vesicle formation was striking in most testes, quantitative analysis indicated that it was more frequent in the ipsilateral testis following unilateral vasectomy. It seems that vasectomy had exacerbated an age-related phenomenon. Lymphocytic infiltration was seen in five of the left testes following vasectomy, in two of the corresponding right testes, but in none of the controls. Two vasectomized left testes, however, showed atrophic changes but no lymphocytic invasion. The results suggest that autoimmune orchitis follows vasectomy but that it may not be the primary cause of degeneration. Attempts to gain positive evidence for mechanical damage, however, were inconclusive.

Analysis of Variance↗
PubMed1999

Freeze-fracture and cytochemical evidence for structural and functional alteration in the axolemma and myelin sheath of adult guinea pig optic nerve fibers after stretch injury.

Recent work in animal models of human diffuse axonal injury has generated the hypothesis that, rather than there being physical disruption of the axolemma at the time of injury, a pertubation of the membrane occurs, which leads, over time, to a dysfunction of the physiology of the axolemmal. This dysfunction is posited to lead to a disruption of ionic homeostasis within the injured axon, leading to secondary axotomy some hours after the initial insult. We decided to test the hypothesis that membrane pump/ion channel activity or function is compromised and this would be reflected in structural changes within the axolemma and myelin sheath. We used freeze fracture and cytochemical techniques to provide evidence for change in membrane structure and the activity of membrane pumps after nondisruptive axonal injury in the adult guinea pig optic nerve. Within 10 min of injury, structural changes occurred in the distribution and number of intramembranous particles (IMPs) in the internodal axolemma. By 4 h, there was novel labeling for Ca-ATPase membrane pump activity at the same site. There was loss of IMPs from the nodal axolemma extending over several hours after injury. There was loss of both membrane pump Ca-ATPase and p-nitro-phenylphosphatase (p-NPPase) activity of the node. There was loss of ecto-Ca-ATPase activity but increased labeling for p-NPPase activity at sites of dissociation of compacted myelin. Quantitative freeze-fracture demonstrated statistically significant changes in membrane structure. We provide support for the hypothesis that structural and functional changes occur in the axolemma and myelin sheath at nondisruptive axonal injury.

4-Nitrophenylphosphatase↗
PubMed1998

Behavior of radial forearm skin flaps transplanted into the oral cavity.

Radial forearm skin flaps transplanted into the oral cavity in patients undergoing treatment for intra-oral tumors frequently acquire a gross appearance resembling that of buccal mucosa. This article reports studies of biopsies of the flaps in 53 patients, of which 21 showed changes at some stage in the follow-up period. The project aims to determine whether 1) the change in the epithelium to a mucosal form is genuine or reactive, 2) a creeping replacement of epidermis results from the surrounding buccal epithelium, 3) alterations in the epidermis could be associated with changes in the dermis, 4) the change is caused by radiotherapy. Examination of the biopsies by resin histology and transmission electron microscopy shows that the changes may be reversible: it suggests that they are reactive in nature, and related to the degree of dermal inflammation, rather than to the effect of radiotherapy. The dermis persists as such and is not replaced by buccal lamina propria.

Adult↗
PubMed1997

Cell death in the developing chick knee joint: I. Spatial and temporal patterns.

The occurrence, distribution and nature of cell death has been studied in the interzone of the developing knee joint of the chick by optical, transmission and scanning electron microscopy. Cell death precedes and accompanies the process of formation of the joint cavity (apart from the femoropatellar component), and is also associated with the surfaces of intra-articular structures as they differentiate within the interzone. Cell death in the knee joint shows many of the morphological characteristics of apoptosis. It is proposed that cell death is one factor in the process of cavity formation in the joint.

Animals↗
PubMed1997

The effects of pre- and postnatal exposure to the nonsteroidal antiandrogen flutamide on testis descent and morphology in the Albino Swiss rat.

Exposure of male Albino Swiss rats to the nonsteroidal antiandrogen flutamide during the period from gestational day (d) 10 to birth resulted in feminisation of the external genitalia and the suppression of growth of the male reproductive tract. In adulthood, testes were found to be located in diverse positions. True cryptorchidism occurred in 10% of cases, whereas 50% of testes descended to the scrotum and 40% were located in a suprainguinal ectopic region. Varying degrees of tubule abnormality were seen in the testes of flutamide-treated animals, ranging from completely normal tubules with full spermatogenesis (and the expected frequency of the stages of spermatogenesis) to severely abnormal tubules lined with Sertoli cells only. For each individual testis, the overall severity of tubule damage was strongly correlated with its adult location, with intra-abdominal testes worst affected and scrotally-located testes least; only the latter contained normal tubules. Similarly, intra-abdominal testes were the smallest in weight and contained the least testosterone. By contrast, postnatal treatment of male rats with flutamide from birth to postnatal d 14 did not impair development of the external genitalia, the process of testicular descent or adult spermatogenesis. These findings confirm that androgen blockade during embryonic development interferes with testicular descent but also demonstrate that (1) prenatal flutamide treatment per se has a detrimental effect on adult testis morphology but (2) the degree of abnormality of the testes is strongly influenced by location.

Androgen Antagonists↗
PubMed1982

Studies on hemolymph nodes. I. Histology of the renal hemolymph node of the rat.

The structure of the left renal hemolymph node of young adult male Swiss albino rats has been studied by optical microscopy of semithin plastic embedded sections. Afferent lymphatics were found, opening into the subcapsular sinus through valved ostia, in a large majority of nodes. Free erythrocytes were found in the afferent lymphatics and in the subcapsular sinus. In the intermediary and medullary sinuses, erythrocytes were mostly attached to sinus macrophages. The efferent lymphatics contained few erythrocytes. All the sinuses macrophages. The efferent lymphatics contained few erythrocytes. All the sinuses contained a stained precipitate of lymph protein. The node is hypoactive in its general form but does not differ essentially from typical lymph nodes, except that it receives, through its afferent lymphatics, lymph containing numerous erythrocytes.

Animals↗
PubMed1982

Studies on hemolymph nodes. III. Renal lymph as a major source of erythrocytes in the renal hemolymph node of rats.

The content of erythrocytes in the intrinsic lymphatics of the kidneys of young adult male Swiss-Albino rats was studied by optical and transmission electron microscopy, in material fixed by vascular perfusion. Erythrocytes were consistently found in lymphatics associated with interlobular, arcuate, interlobar and hilar arteries. They are presumed to have entered lymphatics by diapedesis through peritubular capillaries and veins with which they are frequently in intimate contact. The findings confirm the view that, in the rat, the kidney is an important source of the erythrocytes found in the renal hemolymph node.

Animals↗
PubMedDate not supplied

Differentiation of A-, B- and D-cells of guinea-pig pancreas using semi-thin epoxy-resin sections.

Four-mm2 specimens of guinea-pig pancreas were removed and fixed in buffered 5% glutaraldehyde, dehydrated through alcohols, treated with propylene oxide and impregnated with epoxy-resin and finally polymerised at 70 degrees C. One-mu sections were cut on an ultramicrotome, stretched and adhered to glass slides. They were then deresinized in saturated sodium ethoxide, hydrated and washed thoroughly in running water. Sections were then stained by hematoxylin and eosin. masson, Mallory, Epple, McGadey and the hematoxylin/acid fuchsin/orange G/soluble blue routines using the modified Weigert hematoxylin for the nuclear staining. They were then dehydrated, cleared and mounted in D.P.X. The stainings of the islet cells were compared and only by the latter routine did the D-cells stain adequately.

Animals↗