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Biomedical subjects

R Tiwari

Publications and source records attributed to R Tiwari.

At least 19 recordsLinked to original sources

Cowden's disease. A case report with analyses at the molecular level.

Cowden's disease (multiple hamartoma syndrome) is characterized by multiple hamartomas of ectodermal, endodermal, and mesodermal origin, a high incidence of malignant tumors of the breast and/or thyroid gland, and an autosomal dominant pattern of inheritance. Similar to sporadic breast cancer, chromosomal studies have not elucidated the cause of this syndrome. The authors report the case of a patient with this syndrome and analyze the pattern of amplification or rearrangement of three genes: the HER-2/neu oncogene, the ras oncogene, and the estrogen-inducible gene, pS-2. All three of these genes were present in single copies without translocations. It was noteworthy that three of the most important genes currently studied in relation to breast cancer existed in a unamplified unrearranged state in this patient. Those with clinical manifestations of Cowden's disease may be candidates for prophylactic bilateral total mastectomy, and the authors recommend that these patients undergo this procedure by their third decade of life. An alternative to this approach would entail monthly self examinations, breast examinations by the patient's physician every 3 months, bilateral mammograms every 6 to 12 months, and biopsy of any suspicious lesions. It is crucial, however, that these patients be identified by their mucocutaneous lesions and family history before an underlying malignant lesion develops.

Adult

Management of cervical lymph nodes in patients with head and neck cancer.

The status of the cervical lymph nodes is the single most important prognostic factor in head and neck cancer. Unfortunately, clinical assessment of the neck is not very accurate, although newer imaging techniques such as CT, MRI and ultrasound-guided fine needle aspiration cytology can be used to improve upon the results of clinical palpation alone. While diagnostic techniques remain less than 100% accurate, the risk of occult disease in the neck will remain. If this occurrence is judged to be greater than 15-20%, elective treatment to the neck may then be justified. When the neck is treated surgically, histological information can be gained which has both prognostic and therapeutic implications. Indications for the use of surgery and radiotherapy for the elective and therapeutic management of the neck and the results of such treatment are discussed.

Combined Modality Therapy

Temporal bone resections for carcinoma of the middle ear and the external ear canal.

Petrosectomy has been used in the management of carcinoma of the external ear canal and the middle ear for the last 45 years. In recent years, there have been conflicting reports; some authors advocate a conservative approach, whereas others support an ultraradical approach. Most retrospective studies report patients who have been treated with radiotherapy or surgery as having undergone the primary modality depending on where the patient first presented. No selection criteria seem to have been employed. Although radiotherapy was used postoperatively, the problems of wound healing were not addressed. This study presents our experience with temporal bone resection as described by Lewis and shows that, in combination with patient selection and proper choice of incision, reconstruction and timely postoperative radiotherapy can achieve better results, and the patient's quality of life can be preserved.

Combined Modality Therapy

Squamous cell carcinoma of the nasal vestibule.

We reviewed 30 patients with squamous cell carcinoma of the nasal vestibule to present our experience of their management and to evaluate the prognostic factors that may influence their outcome. For T1 lesions radiotherapy remains the treatment of choice, because of the superior cosmetic result. Fifteen (68 per cent) out of 22 patients with T2 lesions were treated with primary radiotherapy. Surgery however, was eventually required in 16 (72 per cent) out of 22 patients, either as a primary treatment (seven patients) or as salvage surgery (nine patients). For the larger T3 lesions the treatment of choice is surgery followed by post-operative radiotherapy where appropriate. Regional nodal metastases at the time of presentation were a significant indicator of local and regional recurrence and of prognosis. The cause specific five-year survival for patients with an uninvolved neck (22 patients) was 100 per cent compared with 38 per cent for patients with nodal metastases at presentation (eight patients). Elective treatment for uninvolved regional nodes is not considered necessary.

Adult

Discontinuous vs in-continuity neck dissection in carcinoma of the oral cavity.

We compared the results of transoral excision of the primary tumor with discontinuous neck dissection with the results of in-continuity dissection of primary tumor and neck nodes in anteriorly localized squamous cell carcinoma of the oral cavity. We analyzed 27 patients who underwent 28 discontinuous dissections and 34 patients who underwent 40 in-continuity dissections for T2 anterior tongue or floor-of-mouth carcinoma. The overall ipsilateral neck recurrence rate was 11%. The discontinuous dissection group did significantly worse than the in-continuity dissection group, with a neck recurrence rate of 19%. Consequently, the actuarial 5-year survival of patients who underwent a discontinuous dissection was substantially decreased (63%) compared with patients who were treated by an in-continuity dissection (80%). Discontinuous neck dissection, thus, is not to be recommended in oral cancer.

Adult

Experiences with the sternocleidomastoid muscle and myocutaneous flaps.

The use of the sternocleidomastoid muscle and musculocutaneous flaps in the reconstruction of defects arising after surgery for cancer of the head and neck has been a subject of some discussion. Experience with these flaps over a ten year period from 1980 until 1989 is presented. Attention is drawn to the various types of flaps in vogue, their indications to date, benefits and drawbacks. A new reliable compound musculocutaneous flap developed by the author for use in defects of the skull base after total temporal bone excision is presented.

Adult

The efficacy of comprehensive neck dissection with or without postoperative radiotherapy in nodal metastases of squamous cell carcinoma of the upper respiratory and digestive tracts.

Neck recurrence-free curves corrected for local recurrence were compared for 494 patients who underwent 565 comprehensive neck dissections. In 42 dissections, no radicality could be obtained. Of the 523 histologically radical dissections, examination revealed tumor in 352 cases. Patients in whom three or more positive nodes or extranodal spread in one or more nodes were found received postoperative radiotherapy. In the histologically N0 group, the incidence of neck recurrence after 5 years was 3%; in the N+ group as a whole, it was 10%. Analysis of the influence of extranodal spread and the number of positive nodes showed that the group with one or two positive nodes without extranodal spread (that did not receive postoperative radiotherapy) did not statistically differ from the other groups. This suggests that the results of the group with one or two positive nodes without extranodal spread can be improved by postoperative radiotherapy.

Adult

Suprachoroidal injection of sodium hyaluronate as an 'internal' buckling procedure.

Various fractions of sodium hyaluronate were injected into the suprachoroidal space of rabbit eyes via the pars plana as 'internal' buckles. The areas of elevated choroid were diffuse, usually extending over approximately one quadrant. The buckling effect was short-lived, in the range of 12-72 h, but sodium hyaluronate actually survived in the suprachoroidal space up to 10-14 days or more. No significant differences between buckles created by sodium hyaluronate 1 and 2%, or by cross-linked sodium hyaluronate were observed. Internal buckling of the choroid may prove to be a viable adjunct or alternative to conventional buckling procedures in the future.

Animals

Incidence of squamous cell carcinoma of the head and neck: report of 1,000 cases.

The purpose of this paper is to define the incidence of squamous cell carcinoma (SCC) of the head and neck as seen at the Free University Hospital, Amsterdam, the Netherlands, in the last six years, according to the latest revised classification system of the International Union against Cancer (UICC, 1982). In addition, male to female ratios, relative frequencies at the various sites, age distribution, incidence of second or third primary and the relationship of distant metastases to the nodal metastases and the T-stage of the primary lesion are reported. These incidences are compared with those in other countries and the major differences are discussed.

Adult

Lysis of nitrofurantoin-resistant strain of Vibrio el tor.

Both nitrofurantoin-sensitive and nitrofurantoin-resistant strains of Vibrio el tor were found to lyze in the presence of Tris-EDTA at alkaline pH. The rate of lysis was appreciably enhanced by lysozyme. The amounts of intracellular components, viz. proteins and carbohydrates, released from the nitrofurantoin-sensitive strain by Tris-EDTA treatment, were significantly lower than those from the nitrofurantoin-resistant strain. Differences in periplasmic proteins released from Tris-EDTA treated cells of nitrofurantoin-resistant and -sensitive strains were revealed by gel electrophoresis.

Bacterial Proteins

Studies on membrane ATPase activity and lipid level in vibrio el tor under normal and nitrofurantoin resistant conditions.

Nitrofurantoin resistance brought about decreased level of membrane bound ATPase activity in Vibrio el tor as compared to the normal strain while phospholipid as well as total lipid levels in the membrane fraction was increased. Mg++ was found to be the mose effective co-factor for ATPase. At higher concentrations of sodium and potassium ions, ATPase of normal and nitrofurantoin resistant Vibrio el tor responded quite differently. A soluble ATPase extract having low phospholipid content was found to be activated by the phospholipid extracts of Vibrio el tor, phosphatidyl ethanolamine, and also by phosphatidyl choline which is not a constituent of the membrane preparation of Vibrio el tor strains.

Adenosine Triphosphatases

Staffieri's procedure revisited.

Our long-term experience with Staffieri's procedure in 42 patients is presented. Our results were evaluated regarding voice production, aspiration problems, and pharyngocutaneous fistula formation. Approximately 50% of the patients were successfully rehabilitated. Twenty-five percent of the patients did not use the neoglottis for speech production, mostly because of stenosis of the neoglottis. The remaining 25% had serious aspiration problems that needed treatment. It was striking that half of these patients initially benefitted from the Staffieri procedure and had no aspiration problems. These 42 patients were compared with a group of 43 patients who underwent conventional total laryngectomy in the same period. After total laryngectomy and Staffieri's procedure, greater than 35% of the patients had a pharyngocutaneous fistula, while after conventional total laryngectomy the fistula rate was less than 20%. The average postoperative stay in the hospital was longer in the Staffieri group. In the long run, the results of this surgical technique do not justify its further use, especially after previous radiotherapy.

Adult