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Biomedical subjects

S C Luk

Publications and source records attributed to S C Luk.

At least 37 records · Page 2Linked to original sources
PubMed1981

Effects of methylprednisolone and azathioprine on bronchial healing following lung autotransplantation.

The effect of low-dose immunosuppressive therapy upon the healing of the bronchial anastomosis and skin wound following lung autotransplantation was evaluated. Autotransplantation was performed in two groups of dogs: Group 1 (15 dogs) received no immunosuppression and Group 2 (13 dogs) received postoperative immunosuppression with methylprednisolone (2 mg/kg) and azathioprine (1.5 mg/kg). Two to four skin incisions 7 cm in length were made in the dorsal region of each dog. Dogs were put to death at 4, 9, 16, and 23 days postoperatively and the bronchial anastomoses and skin wounds were evaluated by breaking strength measurements. Bronchus and skin breaking strength increased with time in both groups. Bronchus breaking strength was similar in the two groups at day 4 and day 9. However, by day 23 bronchus breaking strength was significantly higher in Group 1 (p less than 0.001). Skin breaking strength was significantly higher in Group 1 on days 9 and 16 (p less than 0.005) and on day 23 (p less than 0.001). Our results suggest that low-dose methylprednisolone and azathioprine significantly affect the breaking strength of both bronchial anastomoses and healing skin incisions following canine lung autotransplantation.

Animals↗
PubMed1980

Brown bowel syndrome in Crohn's disease.

We describe a patient with bowel lipofuscinosis developing subsequent to Crohn's disease of five-years' duration. Lipofuscin pigment was demonstrated in the perinuclear region of smooth muscle cells with the longitudinal and circular coats of the ileal muscularis propria but not in the muscularis mucosa. Electron microscopy showed lipofuscin pigment forming within degenerating mitochondria, confirming the "brown bowel" syndrome as a smooth muscle mitochondrial myopathy.

Aged↗
PubMed1980

Campylobacter jejuni enterocolitis. A clinicopathologic study.

Sixteen patients with diarrhea due to Campylobacter jejuni seen within a one-year period at a general hospital were studied to review the clinical and pathological features of this illness. Campylobacter jejuni causes an acute diarrheal illness often associated with fever, delayed-onset hematochezia, and severe abdominal pain. Roentgenographically, one may see colonic and ileal ulceration. Sigmoidoscopically, the rectal appearance is similar to that from acute idiopathic ulcerative colitis, while rectal biopsy specimens show preservation of glandular architecture and a range of focal inflammatory changes. These changes are most severe in patients with a history of frank blood in stool, provided the specimens are taken within the first week of illness. No correlation between stool frequency, abdominal pain, or fever and the severity of proctitis in rectal biopsy specimens can be drawn, which suggests that the pathogenic determinants for thesse clinical manifestations may not be in the rectum, but higher in the colon or in the small intestine.

Campylobacter↗
PubMed1979

Adenocarcinoma of the trachea: palliative response to cobalt-60 irradiation.

The prognosis of mucus-secreting adenocarcinoma of the trachea is grim. Its large size and infiltrative nature prohibit surgical resection and the response to radiation therapy has been poor. The authors report a case in which notable initial palliation was achieved through cobalt-60 therapy resulting in regression of the patient's tumour and a longer survival than that previously reported in patients with this disease.

Adenocarcinoma↗
PubMed1978

The ultrastructure of urate crystals in gout.

Using correlative scanning and transmission electron microscopic techniques, we studied the ultrastructure of natural and synthetic monosodium urate crystals. The internal architecture of both natural and synthetic urates consists of an interconnecting electron lucent network. This network is different in crystals from tophi, suggesting crystal formation about an electron lucent nidal matrix. Urate crystals from articular cartilage surfaces have smooth faces supporting the hypothesis that acute goat is a two phase process involving first the precipitation of urate crystals in the synovial fluid and second the adherence to the crystals of proteins and cells with the consequent inflammatory response.

Crystallization↗
PubMed1977

Articular cartilage transplantation.

This report describes the biopsy findings in four of 30 patients treated with cadaver osteochondral shell allografts for osteoarthritis in the knee. This study demonstrates that graft cartilage cells can survive in excess of 25 months, and that host bone can completely replace graft bone by creeping substitution. An inflammatory reaction in synovium and bone marrow was found in only one of four cases. Graft failure was related to prolonged down time of donor cartilage in one case and mechanical factors related to osteoarthritis in the apposing femoral surface in other cases. The clinical success of these grafts is attributed to the prolonged viability of cartilage cells, the capacity of host bone to join graft cartilage without histologic reaction, and the host's immunologic tolerance, which obviates the need for immunosuppressive therapy.

Aged↗
PubMed1976

Virus-induced osteosarcoma in rats.

An experimental model for osteosarcoma was developed in which, after Moloney murine sarcoma virus was injected into the tibial marrow space of three strains of inbred neonatal rats, a highly malignant neoplasm arose within ten days. This tumor was readily maintained in tissue culture and was transplantable to adult rats. It arose in the metaphyseal marrow of several bones, was locally invasive, metastasized to the lungs, and histologically resembled osteosarcoma.

Animals↗
PubMed1976

Pseudotumor of temporomandibular joint: destructive calcium pyrophosphate dihydrate arthropathy.

The clinical and pathological features of a tumor of the temporamandibular joint occurring in a 55 year old man, and subsequently identified as a calcium pyrophosphate dihydrate (CPPD) arthropathy, are reported. Crystalline deposits were identified by compensated light microscopy and confirmed with X-ray diffraction, transmission, and scanning electron microscopy. The relationship of this unique case to other clinical presentations of CPPD deposition disease and the implications of the histological features to the pathogenesis of pseudogout are discussed. This case demonstrates that CPPD arthropathy should be included in the differential diagnosis of an arthrosis or of a tumor involving the temporomandibular joint.

Arthritis↗
PubMed1975

Xenogeneic red blood cell degradation in a regional lymph node and dissemination of antigens by circulating lymphocytes.

The degradation of intramuscularly injected autogenic and xenogenic red blood cells are studied with electron microscopy and immunoferritin technique. Autogenic red blood cells are phagocytosed and completely degradated by macrophages within the draining lymph node in a relatively short time. Phagocytosis and initial degradation of xenogeneic red blood cells by macrophages in the draining lymph node are similar; however, portions of the degradation products persist in macrophages as characteristic myelinic-like figures. After 4 days, identical figures appear in large numbers in the adjacent lymphocytes within membrane-bound vacuoles. With the conjugated ferritin antibody technique, these myelinic-like figures are shown to contain antigens of the xenogeneic red blood cells. Subsequently, lymphocytes containing the inclusions are found in the peripheral blood, the marginal zone of the spleen, other lymph nodes, and the bone marrow. As in the draining lymph node the number of plasma cells increases in these organs in areas adjacent to lymphocytes with the inclusions. In a parallel study, uncoated polystyrene spheres injected intramuscularly accumulate and remain localized in macrophages of the draining lymph node. When coated with xenogeneic hemoglobin and membranes, these spheres appear in lymphocytes of the draining lymph node and subsequently in lymphocytes of the blood and spleen.

Animals↗
PubMed1974

Phagocytosis of colloidal carbon and heterologous red blood cells in the bone marrow of rats and rabbits.

Phagocytosis in the bone marrow of rats and rabbits was studied following intravenous injections of colloidal carbon and chicken red blood cells. In both animal species the marrow response to these different foreign particles was quite similar. There was an initial aggregation and degranulation of platelets around the injected particulate matter within the marrow sinuses. Then pseudopods of marrow macrophages appeared in the sinus lumen, forming a web-like structure which trapped and phagocytosed the injected foreign material as well as the platelets. Within the phagosomes of these macrophages, the injected material and platelets were withdrawn into the parenchyma, where degradation or storage occurred. This sequence of events suggests that platelets may play an important role in marrow phagocytosis. The most active cells in marrow phagocytosis are the macrophages. The endothelial cells participated in the phagocytosis of colloidal carbon. The amount of carbon within these cells, however, was small in comparison with that trapped by macrophages. Further, the endothelial cells did not phagocytose chicken red blood cells. These results, being similar to those obtained in lymph, spleen and liver, challenge the concept of the reticuloendothelial system. The term of macrophage system is proposed as a replacement.

Animals↗