Function of the Neurospora crassa mitochondrial tyrosyl-tRNA synthetase in RNA splicing. Role of the idiosyncratic N-terminal extension and different modes of interaction with different group I introns.

The Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (CYT-18 protein) promotes the splicing of group I introns by helping the intron RNA fold into the catalytically active structure. The regions required for splicing include an idiosyncratic N-terminal extension, the nucleotide-binding fold domain, and the C-terminal RNA-binding domain. Here, we show that the idiosyncratic N-terminal region is in fact comprised of two functionally distinct parts: an upstream region consisting predominantly of a predicted amphipathic alpha-helix (H0), which is absent from bacterial tyrosyl-tRNA synthetases (TyrRSs), and a downstream region, which contains predicted alpha-helices H1 and H2, corresponding to features in the X-ray crystal structure of the Bacillus stearothermophilus TyrRS. Bacterial genetic assays with libraries of CYT-18 mutants having random mutations in the N-terminal region identified functionally important amino acid residues and supported the predicted structures of the H0 and H1 alpha-helices. The function of N and C-terminal domains of CYT-18 was investigated by detailed biochemical analysis of deletion mutants. The results confirmed that the N-terminal extension is required only for splicing activity, but surprisingly, at least in the case of the N. crassa mitochondrial (mt) large ribosomal subunit (LSU) intron, it appears to act primarily by stabilizing the structure of another region that interacts directly with the intron RNA. The H1/H2 region is required for splicing activity and TyrRS activity with the N. crassa mt tRNA(Tyr), but not for TyrRS activity with Escherichia coli tRNA(Tyr), implying a somewhat different mode of recognition of the two tyrosyl-tRNAs. Finally, a CYT-18 mutant lacking the N-terminal H0 region is totally defective in binding or splicing the N. crassa ND1 intron, but retains substantial residual activity with the mt LSU intron, and conversely, a CYT-18 mutant lacking the C-terminal RNA-binding domain is totally defective in binding or splicing the mt LSU intron, but retains substantial residual activity with the ND1 intron. These findings lead to the surprising conclusion that CYT-18 promotes splicing via different sets of interactions with different group I introns. We suggest that these different modes of promoting splicing evolved from an initial interaction based on the recognition of conserved tRNA-like structural features of the group I intron catalytic core.

Survival following extended field irradiation in carcinoma of cervix metastatic to para-aortic lymph nodes.

OBJECTIVE: Our goal was to determine survival after extended-field treatment of para-aortic lymph node (PALN) metastasis. METHODS: Thirty-five patients were treated from 1975-1989 for PALN metastasis. The FIGO stages were IB 10, 2A 3, IIB 9, IIIA 1, IIIB 10, 4A 1, and unstaged 1. The diagnosis in 34 patients was by operative staging and in 1 by CT scan and fine-needle aspiration biopsy. Twelve patients had microscopic PALN metastasis (PALN1) and 23 had grossly enlarged lymph nodes (PALN2). Thirty-four patients had extended-field radiotherapy (RT) plus brachytherapy or pelvic boost. Kaplan-Meier estimates were computer calculated for the entire population. Late radiation morbidity was classified by RTOG/EORTC criteria. RESULTS: The 5-year overall survival rate was approximately 29%. Four patients (3 stage IB, 1 stage IIIA) survived without recurrence. All four had extended field RT. The 5-year survival rate was 41.7% for PALN1 cases and 26.1% for PALN2 cases. Three patients (8.6%) had Grade 4 morbidity. CONCLUSIONS: PALN metastasis in stage IB is curable in approximately 30% of cases. The management approach in this series in stage IB was as follows: If PALN metastasis was identified at exploration for radical hysterectomy, the procedure was aborted and extended-field RT administered. In stages IIB through IVA, operative staging or CT scanning with FNA biopsy of suspicious PALN was performed. If PALN metastasis was confirmed, extended-field RT was administered. A 35% 5-year survival rate was observed in the advanced group. The value of chemotherapy for PALN metastasis remains to be defined but results from clinical trials suggest that cisplatin-based chemotherapy may be beneficial.

The right end of the vir region of an octopine-type Ti plasmid contains four new members of the vir regulon that are not essential for pathogenesis.

We sequenced the virD-virE, virE-virF, and virF-T-DNA intergenic regions of an octopine Ti plasmid. Four newly described genes were induced by the vir gene inducer acetosyringone, two of which are conserved in the nopaline-type Ti plasmid pTiC58. One gene resembles a family of phosphatase genes. Each of these genes is dispensable for tumorigenesis.

Radiotherapy for vaginal carcinoma: a 23-year review.

The purpose of the study was to evaluate prognostic variables and morbidity in patients with vaginal carcinoma. 34 patients, mean age 67 years (+/- 8 SD), were treated between 1976 and 1994. 14 patients had a history of prior hysterectomy. In 13 of the 34 patients the tumour site was the upper vagina, in 9 it was the middle third, in 8 the lower third and in 4 the entire length of the vagina. Disease stage was I in 9 patients, II in 16, III in 7 and IV in 2. There were four treatment groups: external beam therapy + intracavitary brachytherapy (Group WPIC, n = 15); external beam therapy + interstitial brachytherapy (Group WPIS, n = 10); external beam therapy alone (Group WP, n = 7); and brachytherapy alone (Group BA, n = 2). Kaplan-Meier estimates and log-rank tests were used to evaluate survival. Disease-specific 5-year survival was 68% for 28 patients with squamous cell carcinoma and 50% for 6 patients with adenocarcinoma (p-value 0.3). 5-year survival was 78% for stage I disease, 63% for stage II, 33% for stage III and 50% for stage IV (p-value 0.2). Vaginal site of carcinoma, history of hysterectomy and treatment type are not significant prognostic factors. Local failure occurred in 2 patients (13%) in the WPIC group, 2 (20%) in WPIS, 3 (43%) in WP and 1 (50%) in BA. 9 patients (26%) had late small/large intestine and/or bladder morbidity. Vaginal morbidity occurred in 15 patients (44%); 9/15 (60%) in the WPIC group and 3/10 (30%) in the WPIS group having vaginal morbidity. This means that, when combining external beam therapy with brachytherapy, interstitial techniques are preferred over intracavitary techniques.

Assessment of accuracy of daily set-ups in prostate radiotherapy using electronic imaging.

The purpose of the study was to assess the accuracy, using electronic portal imaging, of daily set-ups, in patients undergoing radiotherapy for prostate carcinoma. We used a scanning liquid ion chamber to assess the accuracy of set-ups in 25 consecutive patients undergoing a 6 1/2 week course of radiotherapy to the prostate. Electronic images (EPIs) were collected during 33 treatments to each of four ports. The positions of anatomical structures on the EPIs were compared with the same structures seen on digitally reconstructed radiographs (DRRs) made after CT simulation before beginning radiotherapy. Displacements of the EPIs compared with the DRRs were computer-calculated in millimetres in lateral, longitudinal and rotational directions for each port. 11 patients had ports moved because of discrepancies between the EPIs and the DRRs; eight required moves in the first five treatments to correct systematic (simulator) errors. In the right-left and anterior-posterior directions, nearly 95% of the EPIs were within 5 mm of the simulated port position. In the superior-inferior direction, 98% of the ports were within 5 mm of the simulated port position. Two patients had in-plane rotational errors on the lateral ports (8 degrees and 10 degrees respectively). It was concluded that daily electronic imaging is an effective technique for assessing the accuracy of set-ups in prostate radiotherapy.

Enzymatic synthesis of a quorum-sensing autoinducer through use of defined substrates.

Many bacteria, including several pathogens of plants and humans, use a pheromone called an autoinducer to regulate gene expression in a cell density-dependent manner. Agrobacterium autoinducer [AAI, N-(3-oxo-octanoyl)-L-homoserine lactone] of A. tumefaciens is synthesized by the Tral protein, which is encoded by the tumor-inducing plasmid. Purified hexahistidinyl-Tral (H6-Tral) used S-adenosylmethionine to make the homoserine lactone moiety of AAI, but did not use related compounds. H6-Tral used 3-oxo-octanoyl-acyl carrier protein to make the 3-oxo-octanoyl moiety of AAI, but did not use 3-oxo-octanoyl-coenzyme A. These results demonstrate the enzymatic synthesis of an autoinducer through the use of purified substrates.

Osteoradionecrosis of the hyoid induced by combined modality therapy for laryngeal carcinoma.

Contemporary management of laryngeal carcinoma often incorporates multiple modalities of therapy. We report a case of osteoradionecrosis of the hyoid bone in a patient treated with surgery, chemotherapy, and radiation therapy for a supraglottic squamous cell carcinoma. A discussion regarding pathophysiology, radiation dosimetry and treatment options is also presented.

Epidermal growth factor enhances intestinal mitotic activity and DNA content after acute abdominal radiation.

BACKGROUND: Mediators of radiation-induced enteritis and colitis remain undefined. Epidermal growth factor (EGF) is an endogenous peptide that is trophic to the gastrointestinal tract. We tested the hypothesis that EGF enhances DNA synthesis and mitotic activity and prevents acute radiation enteritis after total abdominal radiation. METHODS: Four equal groups (n = 6) of Sprague-Dawley rats were studied: I (control), II (radiation), III (EGF), and IV (radiation + EGF). Animals in groups III and IV received EGF (10 micrograms/kg) every 8 hours for 48 hours before radiation exposure and for 72 hours after radiation, and the remaining animals were given an equal volume of vehicle. Animals in groups II and IV were administered a single dose of abdominal radiation (1000 cGy) 48 hours after the start of either vehicle or EGF. Distal ileum and colon were harvested 72 hours after radiation, examined histologically, and assayed for total DNA content. RESULTS: Group II or radiated animals had diarrhea, significant weight loss (p < 0.05), and decreased food consumption consistent with acute clinical radiation enteritis. Mitotic activity and total DNA content were significantly reduced (p < 0.05) when compared with group I (nonradiated controls). Group IV animals treated with EGF and exposed to radiation did not suffer the acute clinical manifestations of radiation enteritis. In addition, total DNA content and mitotic activity of the terminal ileum increased significantly (p < 0.05), and a significant increase in mitotic activity occurred in the distal colon when compared with radiated controls. CONCLUSIONS: The results of this study suggest that (1) a decrease in mitotic activity and total DNA content occurs early and persists for at least 72 hours after acute radiation, (2) EGF treatment significantly increases small and large bowel mitogenicity in acutely radiated animals, and (3) EGF significantly decrease the acute clinical manifestations of radiation enteritis.

Postoperative hip irradiation in prevention of heterotopic ossification: causes of treatment failure.

Over 4 years, 33 patients (mean age, 52 years) underwent hip surgery followed by single-fraction 700-cGy radiation therapy (RT). Records, port films, and plain radiographs were reviewed to assign Brooker classification levels for severity of heterotopic ossification (HO) and assess the amount of new HO developing after surgery. Nineteen patients (58%) developed radiographic evidence of new HO after surgery. All five patients with three or more risk factors and none of 12 with postoperative Brooker level 0 (no radiographic HO) developed new HO. Ten of 16 treated on postoperative day 1, six of 10 on postoperative day 2, none of three on day 3, two of three on day 4, and one of one on day 5 developed new HO. New HO developed outside the irradiated volume in 11 patients. Surgeons should remove all heterotopic bone whenever possible; RT should be administered within 3 days after surgery; portals should cover all potentially involved soft tissue; and future studies should evaluate larger single fractions (900-1,000 cGy) for prevention of HO in patients with three or more risk factors and/or radiographic evidence of residual HO.

Detection and patterns of treatment failure in 300 consecutive cases of "early" endometrial cancer after primary surgery.

From November 1977 to July 1987, 300 consecutive patients with endometrial carcinoma clinically confined to the uterine corpus underwent primary surgery consisting of at least abdominal hysterectomy and adnexectomy. Patients with aggressive disease characteristics received postoperative radiotherapy. Forty-seven patients (16%) demonstrated recurrent disease from 2 to 125 (median of 12.8) months after surgery. Forty-seven percent of the recurrences were detected within the first year following surgery and 70% by 2 years after hysterectomy. Of the 47 recurrences, 29 were at distant sites, 16 were within the pelvis, and 2 consisted of both local and distant recurrences. Patients treated with pelvic radiotherapy after hysterectomy were more likely to experience distant, rather than local recurrences. Only 7 of the 148 patients (5%) treated with postoperative radiotherapy recurred in the pelvis. Approximately half of the recurrences were detected in asymptomatic individuals; physical examination and chest X-ray were the most useful means to detect disease in patients without symptoms. The combination of history, physical examination, pap smear, and chest X ray detected all of the recurrences. Actuarial survivals at 12, 24, and 36 months after recurrence were 42, 24, and 17%, respectively. The site of recurrence, time interval of surgery to recurrence, and use of postoperative pelvic radiotherapy were statistically related to patient prognosis. The identification of patients at risk of recurrence and more effective adjuvant therapy need to be developed in order to decrease the frequency of recurrence. In order to substantially improve the survival of patients with recurrent disease, more sensitive methods of detection, as well as more effective salvage therapy, will be required.

The National Commission on AIDS.

A decade after the first cases were recognized in the United States, AIDS continues to vex policymakers and fascinate the public. It has been said that AIDS acts as a prism, refracting a spectrum of controversial topics. For bioethicists, these topics include: equity in the allocation of resources for treatment and research; forgoing life-sustaining care and proxy decision making; informed consent in the context of HIV testing and screening; the ethical duties of health care workers to provide care for persons with HIV disease; and competing obligations of health care professionals to patients and to third parties who may be put at risk.

HLA antigens influence resistance to lung carcinoma.

The concept of genetic factors playing a role in the pathogenesis of lung cancer has gained increased attention. The present study was undertaken to reexamine the question of HLA antigen association with carcinoma of the lung. In a study of 90 patients, a significant association occurred between HLA-DR7 and resistance to lung cancer, after accounting for smoking status and sex. HLA class I antigens were also implicated. These results suggest that major histocompatibility complex loci affect carcinoma of the lung.

Adjuvant external beam therapy for pathologic stage I and occult stage II endometrial carcinoma.

Eighty-six patients with pathologic Stage I or occult Stage II carcinoma of the endometrium and myometrial invasion and/or Grade 2 or Grade 3 histologic condition received whole-pelvis external radiation therapy (RT) after extrafascial total abdominal hysterectomy and bilateral salpingo-oophorectomy. Twenty-one patients received 4250 cGy in 25 daily fractions for 5 weeks (Group 1), 28 received 4500 cGy in 25 daily fractions for 5 weeks (Group 2), and 37 received 5100 cGy in 30 daily fractions for 6 weeks (Group 3). Seventeen patients had intravaginal brachytherapy after whole-pelvis RT. Local recurrence developed in two patients (2.3%) (one in Group 1 and one in Group 2). Statistical analysis showed that the depth of myometrial invasion significantly influenced survival (P = 0.016). Tumor grade, pathologic stage, whole-pelvis radiation dose, and the use of brachytherapy did not influence survival. Complications occurred in 9.5% of patients in Group 1, 24.7% in Group 2, and 40.5% in Group 3. Three patients who received brachytherapy had rectal injuries. The authors conclude that 4250 cGy in 25 fractions for 5 weeks of whole-pelvis RT appears to induce fewer complications than higher doses, and may be sufficient to prevent local recurrence in most patients who require adjuvant RT. A clinical trial is needed to determine the optimum dose-time-fractionation regimen.

The efficacy of transrectal ultrasound and prostate cancer.

An increased interest in the diagnosis and treatment of prostate cancer, particularly in the last few years, is reflected in the literature. Numerous articles have been published since 1980 on the subject of imaging of the prostate gland. This article is a review of transrectal ultrasound and its efficacy in the diagnosis and treatment of prostate cancer. Included is a review of the normal prostate anatomy, typical and atypical sonographic features, clinical and radiographic staging of prostate cancer, efficacy of the digital rectal examination, role of ultrasound in prostate cancer screening, surgical treatment, and radiotherapy of prostate cancer.

Sacral plexus injury after radiotherapy for carcinoma of cervix.

A 42-year-old woman developed lower extremity weakness and sensory loss 1 year after external and intracavitary radiotherapy for Stage IB carcinoma of cervix. She has been followed for 5 years posttreatment, and the neurologic abnormalities have persisted, but no evidence of recurrent carcinoma has been found. We believe this to be a rare case of sacral plexus radiculopathy developing as a late complication after radiotherapy. Suggestions are made for improving the radiotherapy technique to prevent this complication in future cases.

Advanced head and neck cancer: low-dose, split-course radiation therapy and simultaneous infusion of 5-fluorouracil and cisplatin.

Twenty-three patients with advanced untreated head and neck cancer, nine patients with recurrent cancer, and six patients with recurrent cancer who underwent surgery and had postoperative persistence of tumor were treated with three 2-week courses of irradiation (1,500 cGy in 10 fractions each) concurrently with cisplatin and a 5-day infusion of 5-fluorouracil. A fourth 2-week course of irradiation (2,000 cGy in 10 fractions) brought the final tumor dose to 6,500 cGy. Twenty patients in the untreated group and three patients in the recurrent group (33%) had a complete response. There were 10 local recurrences in the untreated group (43%), seven in the recurrent group (78%), and three in the persistent group (50%). At 17 months after the start of treatment, the survival rate for the untreated patients was 51%, for the patients in the recurrent group it was 11%, and for the patients in the persistent group it was 20% (P = .03). Most patients experienced toxicity, including nausea, vomiting, weight loss, and mucositis. Clinical trials are necessary to determine whether simultaneous chemotherapy and radiation therapy is an improved method of treatment for advanced head and neck cancer.

Extended-field radiation therapy for carcinoma of the cervix.

The survival of cervical carcinoma patients with paraaortic/high common iliac nodal metastases was evaluated by retrospective chart review during a 13-year interval. Thirty-three patients with cervical carcinoma and surgically documented nodal metastases received primary, extended-field radiation therapy. Overall 2-year and 5-year actuarial survival rates after diagnosis were 37% and 31%, respectively. Survival was analyzed in terms of the variables patient age, clinical stage, tumor histologic type, the presence of enlarged paraaortic/high common iliac lymph nodes, the extent of nodal involvement (microscopic versus macroscopic), the presence of intraperitoneal disease, and whether intracavitary brachytherapy was administered. The use of intracavitary radiation therapy was associated with improved local control and survival (P = 0.017). None of the other variables were statistically related to patient survival. Twenty-two of the patients died of cervical cancer and five are surviving without evidence of cancer. Four patients died of intercurrent disease. Two patients developed bowel-related radiation complications; both patients received chemotherapy concurrent with the radiation therapy. One of the two patients died of radiation enteritis. The use of extended-field radiation therapy does benefit a small group of patients and may result in extended patient survival.

FAM chemotherapy +/- aminoglutethimide in the treatment of pancreatic carcinoma.

Human pancreas contains receptors for estrogens and androgens as well as aromatase activity. FAM chemotherapy was administered to 14 patients with pancreatic cancer (seven at Stage IV). The median survival of these patients was 24.4 +/- 4.8 weeks. FAM chemotherapy plus aminoglutethimide/hydrocortisone (AG/HC) (250 mg bid AG + 20 mg bid HC) was administered to 14 patients (seven at stage IV). The median survival of this group was 17.3 +/- 2.9 weeks (P = 0.74 vs FAM alone). We conclude that addition of AG/HC does not add to the survival of patients with carcinoma of the pancreas treated with chemotherapy.

Multimodality approach to a massive carcinoma of the vulva.

The presentation, combination therapy and clinical course of a patient with a massive vulvar carcinoma are described. Therapeutic aspects in the treatment of such advanced malignancies are considered. A multimodality approach to locally advanced, unresectable vulvar carcinomas may benefit this group of patients.