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Biomedical subjects

D N Slater

Publications and source records attributed to D N Slater.

At least 127 records · Page 7Linked to original sources

A microsurgical technique for simultaneous pancreas and renal transplantation in the rat.

A successful technique of simultaneous pancreatico-renal transplantation into the streptozotocin-induced diabetic rat is described employing a sutureless cuff technique for three of four vascular anastomoses. Reversal of the diabetic state was uniformly observed within 24 hours postoperatively and near-normal renal function was evidenced by 50 days postoperatively. The technique is reliable and reproducible and represents the first report of successful combined transplantation into the diabetic rat.

Animals↗

The origin of platelet count and volume.

Platelet count and volume were measured in man (n = 51) and rat (n = 9). Bone marrow megakaryocyte nuclear and megakaryocyte planimetric areas were measured in man (n = 11) and rat (n = 9). Megakaryocyte cytoplasmic volumes were computed from the planimetric areas. Rat had a significantly higher (p less than 0.001) mean megakaryocyte cytoplasmic volume than man and a significantly wider range (p less than 0.01). Rat mean platelet volume was significantly lower (p less than 0.001) than man while the rat platelet count was significantly higher (p less than 0.001) than man. A computer simulation of the random binary sequential division of megakaryocyte cytoplasm was used to explain these observations. Transmission electron microscopy shows that the site of this binary sequential division is probably the pulmonary circulation. The number of circulating megakaryocytes ml-1 of blood which would maintain the observed platelet counts was computed. The ellipses of constant density associated with the bivariate Gaussian distribution of platelet count and mean volume were computed. Platelet volume distributions of 13 men within two standard deviations of the composite mean of platelet count and mean volume were used to construct the platelet volume distribution signature in normal man. A similar platelet volume distribution signature for rat was constructed. The two distributions were significantly different. Neither rat nor man had a log Gaussian platelet volume distribution, however the measured volume distributions tended towards a log Gaussian curve.

Adult↗

The pathogenesis of amiodarone-induced pigmentation and photosensitivity.

A new method has been used to measure tissue levels of amiodarone and its major metabolite desethylamiodarone. Amiodarone-pigmented skin has a drug and metabolite concentration ten times that of non-pigmented skin. Iodine-rich amiodarone and its metabolite have been detected in secondary lysosomes by energy dispersive analysis of X-rays. Amiodarone induces a phototoxic reaction with an action spectrum in both the UV-B and UV-A wavelengths.

Adult↗

Cutaneous lymphomatoid granulomatosis: a rare cause of recurrent skin ulceration.

We report the case of a 34-year-old male who presented with recurrent skin ulceration due to lymphomatoid granulomatosis. Monoclonal antibody studies showed a high T helper (T4):T suppressor (T8) cell ratio in both the lesions and the peripheral blood. Plasma cells in the infiltrate showed IgA lambda staining but as yet no monoclonal immunoglobulin has been identified in the blood or urine. Lymphocytes bearing markers of immature cells (T10) were observed in the tissue and blood.

Adult↗

Renal morphological changes in idiopathic acute fatty liver of pregnancy.

Renal morphological changes are described in four cases of idiopathic acute fatty liver of pregnancy. Light microscopy showed mild glomerular hypercellularity together with thickening and narrowing of capillary loops. In two cases the tubules showed lipid accumulation which included free fatty acids. Electron microscopy showed mesangial cell interposition between the basal lamina and endothelial cells. Glomeruli contained electron dense material in a subendothelial location. Immunoperoxidase stains showed diffuse segmental deposits of fibrin/fibrinogen and IgM in relation to glomerular capillary loops. IgG and C3 were found in three and two cases respectively. Pathogenetic mechanisms including disseminated intravascular coagulation, immune complex deposition and alterations in lipid metabolism are discussed. Coexistent preeclampsia is considered to be an unlikely explanation for the changes. There is a possibility that these renal changes comprise an early feature of idiopathic acute fatty liver of pregnancy.

Acute Disease↗

Generalized histiocytosis X in the elderly: a light and electron microscope and monoclonal antibody study.

Two elderly female patients are described with generalized histiocytosis X (Letterer-Siwe disease). In each case, a definitive diagnosis was not established until ultrastructural and immunoperoxidase investigations had been performed. The histopathological findings in skin biopsies from each patient were similar. Light microscopy demonstrated a bandlike epidermotrophic cellular infiltrate which included large atypical cells (histiocytosis X cells). Electron microscopy showed that these cells contained Birbeck granules. Monoclonal antibody studies demonstrated the presence of T6, T4 and HLA-DR surface antigens. Lysozyme and alpha-I-antitrypsin were absent from the cells. The associated cellular infiltrate included T4 and T8 positive lymphocytes. It is possible that more cases of generalized histiocytosis X in adults will be identified with the increasing use of specialized histopathological techniques and that the disease is more common than currently believed.

Aged↗

Splenic siderosis and parenteral iron dextran in maintenance haemodialysis patients.

The histological features of 40 spleens surgically removed from maintenance haemodialysis patients are reported. Twenty-four of the 40 (60%) showed massive iron loading and a significant direct correlation was found between iron loading and the amount of intravenous iron dextran administered. Since parenteral iron dextran appears to be a major factor in causing iron overload in haemodialysis patients its use as a method of iron replacement in these patients would appear inappropriate.

Blood Transfusion↗

A cutaneous manifestation of acute lymphoblastic leukaemia mimicking urticaria pigmentosa.

A 37-year-old female developed what appeared to be the typical cutaneous manifestations of urticaria pigmentosa. These preceded the peripheral blood changes of acute null cell lymphoblastic leukaemia and skin biopsy revealed that the cutaneous changes were due to leukaemic infiltration. Chemotherapy resulted in clearance of the rash. The importance of skin biopsy in patients presenting with suspected urticaria pigmentosa is emphasized.

Adult↗

Monocytic sarcoma of the sclera.

A patient with acute monocytic leukaemia and gross ocular involvement successfully treated with local irradiation is described. Leukaemic infiltration of the sclera developed at a time when the patient appeared to be in haematological remission. Despite the frequency of extramedullary disease in monocytic leukaemia the diagnosis of monocytic sarcoma may be very difficult.

Aged↗

Gastrointestinal complications of mycosis fungoides.

Mycosis fungoides (MF) is an uncommon T-cell lymphoma which characteristically involves the skin. Two patients with MF are described who developed fatal complications secondary to involvement of the gastrointestinal tract. One developed malabsorption due to small intestinal involvement; the other had a massive haemorrhage from an ulcerated nodule of tumour in the stomach. The potential for extracutaneous spread is discussed, and it is emphasized that bowel infiltration should be considered in any patient with MF who develops gastrointestinal symptoms or complications.

Humans↗

Platelet production: a computer based biological interpretation.

The platelet volume distribution was measured in rat and rabbit in normal steady state platelet production. The animals were then sacrificed and the planimetric megakaryocyte and nuclear areas in each animal were measured using histological techniques. These areas were used to obtain an estimate of the megakaryocyte, megakaryocyte cytoplasm and nuclear volume distributions. The production, by physical fragmentation, of the platelet population from the measured megakaryocyte cytoplasm volume distribution was simulated on a computer. The platelet volume distribution predicted by physical fragmentation was then compared with the measured circulating platelet volume distribution from each animal. The physical fragmentation theory gave an accurate quantitative prediction of the observed platelet volume distribution over the whole volume range. Furthermore fragmentation theory predicted the mean platelet volume, the mode, the maximum frequency of the platelet volume distribution and the range of this distribution. Autopsy studies of megakaryocytes volume distributions in healthy man were fragmented to obtain predicted normal platelet volume distributions from the computer simulation. These distributions were compared with measured circulating platelet volume distributions from apparently healthy men who had a similar mean platelet volume. The platelet volume distribution predicted by physical fragmentation was again in quantitative agreement with the measured distribution over the whole volume range. This study provides further evidence that platelet production from megakaryocyte cytoplasm is by physical fragmentation. Furthermore the computer simulation suggests that the mode of production has a specific form. It also explains why different mammals have different mean platelet volumes.

Animals↗

The megakaryocyte in thrombocytopenia: a microscopic study which supports the theory that platelets are produced in the pulmonary circulation.

Thrombocytopenia can increase platelet production and thereby facilitate investigations into the mechanism. Megakaryocytes in the bone marrow, lung, spleen and liver have been studied by light and transmission electron microscopy after 6 days of experimentally induced thrombocytopenia in the rabbit. The findings support the theory that platelets are produced in the pulmonary circulation by the physical fragmentation of megakaryocyte cytoplasm.

Animals↗

The needle necropsy.

The technique of limited necropsy by histological examination of needle tissue cores obtained percutaneously is indicated when a full necropsy is not justified owing to the risk of infection or when tissue for special investigations is needed soon after death without recourse to full necropsy facilities. The method is ideal for detecting conditions producing diffuse changes in an organ. Because the cadaver is preserved essentially intact relatives who refuse permission for a standard necropsy might consent to a needle necropsy if this option is offered to them.

Adult↗

Abnormal intrapulmonary platelet production: a possible cause of vascular and lung disease.

It is postulated that platelets are not produced by megakaryocyte budding within the bone marrow but by physical fragmentation in the pulmonary circulation. Alterations in the nature of the production site (the pulmonary vessels and their concomitant biochemical environment) or changes in the antecedent megakaryocyte cytoplasmic volumes with a concomitant alteration in protein structure can produce platelets with a mean volume larger than normal. If such platelets are more reactive then they may be involved in atherogenesis and arterial thrombosis. Furthermore several pulmonary pathological states may arise from dysfunction during pulmonary platelet production.

Blood Platelets↗

Rat pancreas allotransplantation: a short term comparison of rejection patterns with different methods of exocrine drainage.

Pancreas transplantation has been performed in the rat to study the effect on rejection of duct ligation, duct obliteration and duct open intraperitoneal drainage. On day six, an acceleration of graft damage was seen in the duct ligated and obliterated allografts compared to the duct open group. However, by day 11, rejection was complete in all three groups. In comparison with pancreatic isografts, the histological diagnosis of rejection can be difficult to define, particularly in the duct ligated and obliterated groups. The most useful criterion was the localisation of the cellular infiltrate to the walls of small veins and within the islet of Langerhans.

Animals↗