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Biomedical subjects

N Platt

Publications and source records attributed to N Platt.

At least 19 recordsLinked to original sources
PubMed1995

Cloning and expression of the beta-N-acetylglucosaminidase gene from Streptococcus pneumoniae. Generation of truncated enzymes with modified aglycon specificity.

The gene encoding a beta-N-acetylglucosaminidase from Streptococcus pneumoniae has been obtained by screening an expression library for beta-N-acetylglucosaminidase activity. Clones of different nucleotide sizes each having arylglycoside activity were obtained, and DNA sequencing revealed a gene of 3933 base pairs possessing typical bacterial transcription initiation and termination sequences and terminating in an ochre stop codon. Computer analysis of the translated protein of 1311 amino acids (144,210 Da) identified a tandem repeat within which lies a sequence homologous with six other hexosaminidase gene products from a wide variety of species ranging from bacteria to humans. Also found were an amino-terminal putative secretion signal peptide and a carboxyl-terminal cell sorting/anchorage motif typically found in over 20 other Gram-positive surface proteins. The expression of an almost complete DNA clone in Escherichia coli produced a functional and authentic beta-N-acetylglucosaminidase with aglycon specificity identical to the wild-type enzyme. However, enzymes produced from truncated DNA clones show more restricted aglycon specificity and are unable to hydrolyze terminal beta 1-2GlcNAc residues from N-glycans containing a bisecting N-acetylglucosamine. The availability of these clones allows structural analyses to be made of catalytic and oligosaccharide recognition protein domains that enhance functional activity.

Acetylglucosaminidase↗
PubMed1991

The L5 epitope: an early marker for neural induction in the chick embryo and its involvement in inductive interactions.

The pattern of expression of the carbohydrate epitope L5 was studied during early development of the chick neuroepithelium. Immunoreactivity first appears during gastrulation, at mid-primitive streak stage, and persists until at least 3.5 days of development. The epitope is expressed on all the components of the developing nervous system, both central and peripheral. In immunoblots, the antibody recognises a major component of about Mr 500,000 and several more minor components of lower molecular mass. If a Hensen's node from a donor embryo is transplanted into the area opaca of a host embryo, L5 immunoreactivity appears in the epiblast surrounding the graft. If hybridoma cells secreting the antibody are grafted together with Hensen's node into a host chick embryo, the induction of a supernumerary nervous system is inhibited. We suggest that the L5 epitope is an early and general marker for neural induction and that it may be involved directly in inductive interactions.

Animals↗
PubMed1987

Aneurysmal bone cyst of the mandible.

The case of a 48-year-old male patient with a slowly growing mass in the right molar region of the mandible is presented. The biopsy specimen showed an aneurysmal bone cyst. After radiation therapy failed to arrest the process, the patient was treated surgically via an external approach. Between the time of the initial presentation and the date of definitive surgery 9 months later, a dramatic change was noted in the roentgenographic pattern of the lesion, demonstrating early and late stages in the development of an aneurysmal bone cyst. There has been no recurrence in a 17-year follow-up period.

Bone Cysts↗
PubMed1983

Primary cutaneous mucoepidermoid carcinoma of the anterior neck.

Cutaneous mucoepidermoid carcinoma is quite rare. We describe a case of extrasalivary cutaneous mucoepidermoid carcinoma in the head and neck region. The theories dealing with the origin of these tumors in the sweat and salivary glands are discussed, and the literature concerning these lesions reviewed. We believe this to be the first description of an extrasalivary mucoepidermoid carcinoma in the head and neck region or other sites that normally contain mucous glands.

Carcinoma↗
PubMed1982

Preoperative chemotherapy for giant cell carcinoma of the thyroid.

Reported is the case of a 24-year-old white man with inoperable giant cell carcinoma of the thyroid who achieved tumor regression following therapy with bleomycin, Adriamycin and cisplatinum. After 2 courses of chemotherapy, the tumor was deemed operable, and the patient underwent total thyroidectomy followed by radiation to the neck and upper mediastinum without maintenance chemotherapy. Two-and-one-half years after the initial diagnosis, he developed pulmonary metastases which again responded to Adriamycin and cisplatinum therapy. The above approach suggests that inoperable thyroid carcinoma can be made operable by preoperative combination chemotherapy. This treatment program deserves further exploration for a greater number of patients.

Adult↗
PubMed1981

Splenic pseudocyst associated with hypersplenism.

A patient with hypersplenism, who was found to have a splenic pseudocyst containing an organized hematoma, is described. There are only two patients with splenic pseudocyst and hypersplenism and an additional two patients with splenic cysts and hypersplenism reported in the world literature. The hypersplenism associated with splenic cysts and pseudocysts is explained on the basis of an expansion of the plasma volume and the total blood volume, an increased destruction of red blood cells and a pooling of blood in the enlarged spleen. The combined use of ultrasonography and computerized tomography has increased the accuracy of noninvasive diagnosis and made more invasive examinations unnecessary. When the ultrasound is technically unsuccessful or when it shows a mixed echo pattern, one should resort to computerized tomography with which it is possible, almost invariably, to differentiate between cysts and neoplasms.

Adult↗
PubMed1978

Gangrene of the stomach: a case of acute necrotizing gastritis.

Of the several causes of gastric necrosis, the rarest is acute necrotizing gastritis which appears to be a variant of phlegmonous gastritis. In acute necrotizing gastritis all four major gastric vessels are patent, but gastric gangrene occurs secondary to an over-whelming necrobiotic infection. The case presented herein is of unusual interest because it appears to be only the third reported case of acute necrotizing gastritis with overt gangrene of the stomach. Review of the literature on suppurative gastritis emphasizes the rarity and high morbidity of acute necrotizing gastritis; the patient reported on in this study, however, survived after subtotal gastrectomy and antibiotic therapy. It is our opinion that debridement by gastrectomy must be performed in those patients with transmural, diffusely infected, nonviable gastric tissue.

Female↗
PubMed1977

Cancer in chronic ulcerative colitis. Diagnostic role of segmental colonic lavage.

Saline colonic lavage in 74 patients with chronic ulcerative colitis was performed utilizing a commercially available dental irrigating unit through a polyethylene catheter in the biopsy channel of a colonoscope or through a sigmoidoscope via a lavage-aspirating double-lumen probe. Six patients were found with colonic carcinoma. Two diagnoses of malignancy were established by cytologic smears and cell block alone. Two patients had positive mucosal biopsies and cell block. One patient with a hepatic flexure carcinoma and a second patient with a malignancy proximal to the left colon stricture were missed by these techniques. Considering the established proclivity for carcinoma in these patients, it is felt that segmental lavage in areas of stricutre, grossly dostorted mucosa, or endoscopically inaccessible areas represents a valuable adjunct in the diagnosis of carcinoma in chronic ulcerative colitis.

Adenocarcinoma↗
PubMed1977

Ileorectal anastomosis for inflammatory disease of the colon.

We have reported long-term results in the cases of 42 patients following total colectomy and ileorectal anastomosis for inflammatory bowel disease. In this group, 35 patients had Crohn's disease and seven had ulcerative colitis. Five of those seven patients with ulcerative colitis had carcinoma of the colon at the time of colectomy. A diverting loop ileostomy was constructed in 14 of the 35 patients who had Crohn's colitis at the time of operation, and none of these patients had any anastomotic leakage either before or after the ileostomy was closed. However, there patients with Crohn's colitis in whom anastomotic leaks developed postoperatively; all three patients died. In the group with ulcerative colitis, one patient had an anastomotic leak but there was no operative nortality. Of the 29 patients with Crohn's disease followed for one to 18 years, 12 (41 per cent) developed recurrences in the ileum and/or rectum, and seven of these patients had to have their anastomoses taken down.

Adolescent↗
PubMed1977

Ileorectal anastomosis in patients with Crohn's disease of the colon.

Thirty-seven patients were studied who had an ileorectal anastomosis performed for Crohn's disease of the colon. Twenty-nine were done as a primary procedure and in eight the anastomosis was made after previous total or segmental colectomy. Three patients developed anastomotic leaks and all three patients died. No patient who had a diverting loop ileostomy performed at the time of ileorectal anastomosis developed anastomotic leaks before or after the ileostomy was closed. Of the 37 patients, three died postoperatively and another five have had less than a one year follow-up. Of the remaining 29 patients, 12 (41%) had recurrences in either the rectum or ileum. Half of the recurrences took place five or more years after surgery. Seven of the 12 patients with recurrences have had their anastomoses taken down. When this recurrence rate of 41% is compared with the recurrence of ileitis in patients after total colectomy and ileostomy for Crohn's disease of the colon, the incidence of recurrence is, as shown in many reports, not markedly dissimilar. Of the patients who develop a recurrence after ileorectal anastomosis, only about half will have to have their anastomoses taken down. In our study, 59% of the patients had no recurrence and another 20-5% had a recurrence but did not require 'take down' of the anastomosis. Thus, almost 80% of our patients at the time of this report have been able to lead a life unencumbered by an ileostomy, making ileorectal anastomosis for this disease a desirable procedure to consider in selected patients.

Adolescent↗
PubMed1976

Reticulum cell sarcoma of the cecum and macroglobulinemia: a case report.

A case report is presented of an 81-yr old male who developed a reticulum cell sarcoma of the cecum while on immunosuppressive therapy for 13 yr for a primary diagnosis of macroglobulinemia. The considerable overlap between immunoproliferative disorders and the increased incidence of malignancies in patients receiving immunosuppressive therapy are discussed.

Aged↗
PubMed1976

The surgical management of toxic dilatation of the colon: a report of 28 cases and review of the literature.

Experience with 28 patients with toxic dilatation of the colon is reviewed. The operative mortality in this series was 32% (9/28). Eight of the 9 patients who died were found to have colonic perforations at operation; in contrast, the group of patients with no perforations had a mortality rate of only 6%. Colonic perforation and sepsis were the most significant factors contributing to mortality and morbidity in this series. A review of the literature showed an overall operative mortality rate of 19.5% for patients with toxic megacolon; the mortality rate was 41% for patients with perforations and 8.8% for patients without perforations. It appears that the keystone to successful management is the avoidance of colonic perforation and sepsis; protracted medical management of toxic megacolon seems to have been at least partly responsible for these complications. Sixteen of the 18 survivors following subtotal colectomy required removal of the rectum within 9 months because of continued symptoms and disease in the rectal stump.

Adolescent↗
PubMed1975

The need for modification of the polyvinyl sponge model of connective tissue growth. Histoligic and biochemical studies in the rabbit.

Quantitative histopathologic and biochemical comparisons were made between polyvinyl sponge capsular and sponge tissue in the rabbit on different days after subcutaneous implantation. Up to 9 days the predominant cell type in the capsular tissue is the fibroblast and in the sponge it is the neutrophil. During this time period the sponge tissue shows lower rates of (14C) proline and (14C) cytidine incorporation and lower rates of total (14C) collagen synthesis than the surrounding capsule. Different gel electrophoretic patterns of isolated radioactive proteins are found in sponge and capsule at 6 days. These biochemical differences appear to be related to the small number of fibroblasts, relative to granulocytes present in sponges during the first 9 days after implantation. It is suggested that future biochemical investigations of the early phase of connective tissue reactions (first 9 days) in this model utilize sponge capsular tissue within 1 cm of the sponge edge instead of the sponge and its contents.

Animals↗
PubMed1974

Granulomatous peritonitis due to cellulose fibers from disposable surgical fabrics: laboratory investigation and clinical implications.

Two patients with postoperative granulomatous peritonitis were found to have lesions with a distinctive type of foreign body. Laboratory investigation revealed this foreign body to be cellulose, morphologically identical with fibers derived from disposable surgical gowns and drapes, and cotton. The same type of foreign body granulomas was produced experimentally by introducing lint prepared from these gowns and drapes into the peritoneal cavities of rats. Since disposable gowns and drapes are being used with increasing frequency, cellulose lint derived from these sources should be added to the list of hazardous foreign materials which are potential wound contaminants.

Adolescent↗