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Biomedical subjects

D Clarke

Publications and source records attributed to D Clarke.

At least 199 records · Page 11Linked to original sources
PubMed1985

Effects of maternal ethanol infusion on fetal cardiovascular and brain activity in lambs.

Ethanol (1 gm/kg of maternal body weight administered over 1 hour) was infused intravenously into 11 chronically prepared pregnant ewes between 128 to 137 days' gestation. Fetal breathing movements were suppressed for 9 hours following ethanol administration, and both high- and low-voltage fetal electrocortical activity were suppressed for 3 hours and replaced by intermediate-voltage electrocortical activity. Fetal blood gases and pH were not altered. These data support the hypothesis that ethanol suppresses fetal breathing movements by a direct central mechanism rather than indirectly by alteration of electrocortical activity.

Animals↗
PubMed1985

192Ir pharyngoepiglottic fold interstitial implants. The key to successful treatment of base tongue carcinoma by radiation therapy.

Twenty-eight patients with squamous carcinomas of the base tongue were seen and evaluated in a conjoint Head and Neck Tumor Board at Stanford between 1976 and 1982. Fourteen patients were treated by combined external beam and interstitial irradiation, 11 of whom had Stage III and IV carcinomas (American Joint Committee). An initial dose of 5000 to 5500 rad was first delivered by external beam irradiation in 5 to 5.5 weeks, followed approximately 3 weeks later by an iridium 192 (192Ir) interstitial implant boost by the trocar and loop technique. The key to successful treatment of these neoplasms was found to be the use of a lateral percutaneous cervical technique, which placed horizontal loops through the oropharyngeal wall above and below the hyoid bone; the superior loop included the pharyngoepiglottic fold and the tonsilloglossal groove. Standard multiple loop implants (submentally inserted) of the base tongue from the vallecula anteriorly to the circumvallate papillae were also used routinely. This approach has been successful, since 10 of the 14 patients (71%) remain without evidence of disease (mean follow-up, 32 months). There have been only two local recurrences, both on the pharyngoepiglottic fold in patients who did not receive the now standard pharyngoepiglottic fold/lateral pharyngeal wall implants. No patients have relapsed after 18 months. The other 14 patients were treated prospectively during the same period by combining initial resection, radical neck dissection, and postoperative irradiation. In this group, there were more locoregional failures compared to the group treated with radiation therapy alone (5 tongue recurrences and 7 neck relapses); in addition, more severe complications were noted in these 14 patients who received surgery and postoperative irradiation. The authors believe that combined external beam and interstitial irradiation is effective treatment for base tongue carcinomas, especially when the high-dose distribution includes the adjacent tonsilloglossal groove, pharyngoepiglottic fold, and oropharyngeal wall to and below the level of the hyoid bone, in addition to treating an adequate base tongue volume.

Brachytherapy↗
PubMed1985

Transplantation of embryonic ventral forebrain neurons to the neocortex of rats with lesions of nucleus basalis magnocellularis--I. Biochemical and anatomical observations.

Unilateral ibotenic acid lesions of the rat nucleus basalis magnocellularis produce approximately 60% depletion of choline acetyltransferase activity in ipsilateral frontal and frontoparietal neocortex. This depletion, which represents the loss of most of the extrinsic neocortical cholinergic input, is stable for at least 6 months. Embryonic ventral forebrain neurons survive transplantation to such cholinergically denervated neocortex. Cholinergic cells abound within these transplants and appear able to reinnervate the cholinergically depleted host cortex, as assessed histochemically and by measurement of choline acetyltransferase activity. Outgrowing fibres may extend beyond 2 mm from the grafts and often appear to be organized in an appropriate laminar pattern within the host cortex. Peptidergic neurons are sparse within the grafts and their fibres frequently appear unable to grow into the host tissue. Control grafts of non-cholinergic embryonic hippocampal cells survive well but have no effect on cortical depletions of acetylcholinesterase or choline acetyltransferase activity. Reconstruction of the extrinsic cholinergic input to the cortex by transplantation provides a useful tool for understanding the functions of this pathway.

Animals↗
PubMed1984

Combined interstitial hyperthermia and brachytherapy: Institute Gustave Roussy technique and preliminary results.

In 1981, a protocol was developed at the Institute Gustave-Roussy, utilizing combined interstitial hyperthermia and brachytherapy, to treat recurrent tumors in previously irradiated areas. This protocol consisted of interstitial hyperthermia, 44 degrees C for 45 minutes, followed immediately by iridium 192 curietherapy, delivering 30 Gy in 2 or 3 days to the tumor volume. Fourteen implantations have been performed in 11 patients. Complete eradication of tumor has been achieved thus far in 10 cases. Two patients were not evaluable because of rapid death resulting from diffuse metastases, and two patients demonstrated a partial response (greater than 50% tumor reduction). Treatment has been generally well tolerated despite prior high dose irradiation. There has been only one serious complication-a large area of painful necrosis following retreatment of a recurrent floor of mouth carcinoma. Special "metallic-plastic" tubes were developed to improve tissue tolerance. We were able to document that a high and homogeneous temperature could be delivered throughout the tumor volume. The technical innovations, and the techniques of implantation and temperature documentation are described below.

Adenocarcinoma↗
PubMed1984

Long-term injury in B-lymphocyte precursor cells in repeatedly-irradiated mice.

Mice irradiated with 4 doses of 4.5 Gy X-rays at 3-week intervals, demonstrated long-term proliferative defects in B lymphocytes. There was a reduced mitogenic response to bacterial polysaccharide (30%), a lower concentration (35%) of B-lymphocyte colony-forming cells (BL-CFC) in agar with an increased proportion of clusters (X 2), and a reduced concentration (30%) of plaque-forming cells. Grafts of thymocytes were able to restore the levels of BL-CFC in the short term, but in the long term large grafts of femoral marrow cells were much better in restoring the numbers of BL-CFC. The reduced mitogenesis (25%) of splenocytes by concanavalin A and the diminished number of plaque-forming cells, may suggest persistent injury in T-B cell cooperation.

Animals↗
PubMed1984

Operation for discrete subvalvular aortic stenosis.

Over the past 20 years, 37 patients (31 children and six adults) have undergone operations for discrete subvalvular aortic stenosis. Prior to 1975, resection of the subvalvular membrane alone was the procedure of choice. However, the recurrence rate was high (36%). Since 1975, resection of the membrane plus left ventricular myectomy has been routine. The recurrence rate in this group has been lower (20%) but is still high. Overall, 11 patients (30%) have had significant recurrence (average gradient 63 mm Hg). Eight of these 11 have undergone a second operation with re-resection of a membrane and left ventricular myectomy. One patient died and in three others (42%) significant symptoms and gradients remained. One of these three has undergone a successful aortoventriculoplasty, and two patients are awaiting a similar operation. Lessons learned from this experience include the following: (1) Regardless of the type of initial operation, a significant rate of recurrence can be anticipated. (2) Progressive aortic insufficiency and fibromuscular tunnel stenosis occur commonly unless adequate relief of the obstruction is achieved by the first operation. (3) Because repeat resection with left ventricular myectomy is unlikely to be effective when aortic insufficiency and/or tunnel stenosis are present, aortoventriculoplasty should be employed as the definitive reoperative procedure.

Adolescent↗
PubMed1983

Fat necrosis of the breast simulating recurrent carcinoma after primary radiotherapy in the management of early stage breast carcinoma.

Between March 1973 and December 1980, 76 patients with Stage I or II breast carcinoma were treated by biopsy and definitive radiation therapy at Stanford University Medical Center. There were 78 treated breasts since two patients had bilateral carcinomas at presentation. During a median follow-up period of 29 months, eight patients developed discrete masses in the treated breast. In four of these patients biopsied tissue revealed recurrent carcinoma yielding a local control rate of 95%. Four additional patients had lesions which were clinically indistinguishable from recurrent cancer. Biopsy specimens, however, revealed fat necrosis of the breast. The clinical and pathologic features of this entity are described. It is imperative that clinicians be aware of this treatment sequelae so that conservative diagnostic procedures may be used and breast deformity minimized. If postirradiation fat necrosis is considered, mastectomy for suspected persistent or recurrent disease may be avoided.

Biopsy↗
PubMed1983

Analysis of cosmetic results and complications in patients with stage I and II breast cancer treated by biopsy and irradiation.

Between May, 1973 and December, 1980, 78 Stage I and II breast carcinomas in 76 patients were treated by biopsy and radiotherapy with curative intent. With a maximum follow-up of 10 years, a minimum of 2 1/2 years and a median follow-up of 3 1/2 years, a loco-regional control rate of 97% was obtained. Cosmetic results and treatment complications were studied. Patient characteristics, tumor size, excisional biopsy technique, axillary staging procedure and radiotherapy techniques were analyzed and all found to be important factors affecting cosmesis and complications. The most common complications included transient breast edema observed in 51% of patients, breast fibrosis (usually mild) seen in 23% of the population, axillary hematoma or seroma formation in 15%, mild arm edema in 14% and basilic vein thrombosis in 10% of patients. The causes of these and other less frequent complications are discussed. The overall cosmetic result was excellent in 78%, satisfactory in 18% and unsatisfactory in 4% of patients. Recommendations for improving cosmetic results minimizing complications are made. In our prospective trial, the high loco-regional control and good cosmesis supports the use of excisional biopsy and radiation therapy in patients with Stages I and II breast carcinoma.

Adenocarcinoma↗
PubMed1983

Surgical therapy for a complication of Kawasaki's disease.

Mucocutaneous lymph node syndrome (MLNS), or Kawasaki's disease, affects thousands of infants and children each year and is associated with a high incidence of coronary artery aneurysm, which may lead to subsequent myocardial infarction. Successful use of the right subclavian-axillary artery to bypass a thrombosed aneurysm of the left anterior descending coronary artery is documented angiographically and forms the basis of this report. A management plan for MLNS patients is proposed.

Aneurysm↗
PubMed1983

Irradiation as an alternative to mastectomy for early breast cancer.

Between May 1973 and December 1980 there were 76 patients (78 breasts) with clinical stage I or II breast carcinoma treated by biopsy and definitive radiotherapy at Stanford University Medical Center. Local-regional control has been achieved thus far in 76 of 78 cases (97 percent) with a median follow-up time of 26 months. Transient lymphedema of the breast, arm edema and breast fibrosis were the most commonly noted complications. The cosmetic result was analyzed and scored as excellent in 78 percent, satisfactory in 18 percent and unsatisfactory in 4 percent. The three unsatisfactory results occurred in patients in whom severe fibrosis developed as a result of suboptimal radiation techniques. Interdisciplinary cooperation among surgical, medical and radiation oncologists is important. The 97 percent local-regional control and the 96 percent excellent-to-satisfactory results support the use of primary radiotherapy in early stage breast carcinoma.

Breast Neoplasms↗
PubMed1982

Breast edema following staging axillary node dissection in patients with breast carcinoma treated by radical radiotherapy.

Seventy-four patients with carcinoma of the breast were treated by irradiation without a mastectomy at Stanford between May 1973 and March 1980. Seventy-six breasts were treated because two patients had bilateral simultaneous cancers. Breast edema was noted in 41% of these cases. Analysis of potential predisposing factors revealed that this complication occurred primarily in patients who received a staging axillary lymph node dissection. Lymphedema occurred in 26 of 33 breasts (79%) in patients who had staging axillary dissections; this complication developed in only three of 12 (25%) with axillary samplings and two of 31 (6%) with no axillary surgery. Two groups of patients were identified: (1) 28 patients whose breast edema occurred early (prior to or during radiation therapy), and (2) three patients with late onset edema that developed several months postirradiation. The early edema, which is clearly related to axillary lymph node dissection, gradually improved during the follow-up period with complete or near complete resolution expected by three years. Late onset edema was rare, appears to be related to an axillary radiation dose greater than 5500 rad, and may be irreversible. There was no correlation of breast edema with tumor stage, radiation time/dose factors, the use of bolus, patient weight, or breast size.

Adult↗