The yiaE gene, located at 80.1 minutes on the Escherichia coli chromosome, encodes a 2-ketoaldonate reductase

An open reading frame located in the bisC-cspA intergenic region, or at 80.1 min on the Escherichia coli chromosome, encodes a hypothetical 2-hydroxyacid dehydrogenase, which was identified as a result of the E. coli Genome Sequencing Project. We report here that the product of the gene (yiaE) is a 2-ketoaldonate reductase (2KR). The gene was cloned and expressed with a C-terminal His tag in E. coli, and the protein was purified by metal-chelate affinity chromatography. The determination of the NH2-terminal amino acid sequence of the protein defined the translational start site of this gene. The enzyme was found to be a 2KR catalyzing the reduction of 2, 5-diketo-D-gluconate to 5-keto-D-gluconate, 2-keto-D-gluconate (2KDG) to D-gluconate, 2-keto-L-gulonate to L-idonate. The reductase was optimally active at pH 7.5, with NADPH as a preferred electron donor. The deduced amino acid sequence showed 69.4% identity with that of 2KR from Erwinia herbicola. Disruption of this gene on the chromosome resulted in the loss of 2KR activity in E. coli. E. coli W3110 was found to grow on 2KDG, whereas the mutant deficient in 2KR activity was unable to grow on 2KDG as the carbon source, suggesting that 2KR is responsible for the catabolism of 2KDG in E. coli and the diminishment of produced 2KDG from D-gluconate in the cultivation of E. coli harboring a cloned gluconate dehydrogenase gene.     

Detection of trisomy 3 in primary gastric B-cell lymphoma by using chromosome in situ hybridization on paraffin sections

Recently, new backscatter factors for low-energy x rays derived from Monte Carlo calculations have been recommended in the UK code of practice for kilovoltage dosimetry published by (IPEMB). As these data, presented as a function of half-value layer, do not take account of the variation of the x-ray spectra for a given HVL, we have undertaken an experimental study in order to determine BSG for the beam qualities provided by a Darpac 2000 therapy unit. A RTL detector such as Li2B4O7:Cu and parallel-plate ion chambers specially designed for low-energy x-ray dosimetry have been used. The results obtained show very good agreement between the TLD and the Monte Carlo calculations, confirming values obtained by other authors with lithium borate TLD. On the contrary, the results obtained with plane-parallel ion chambers show discrepancies up to 9% that are discussed.     

Collateral hemodynamics after middle cerebral artery occlusion in Wistar and Fischer-344 rats

We investigated whether the difference in infarction volume after occlusion of a long proximal segment of the middle cerebral artery between Wistar and Fischer-344 rats, is caused by differences in collateral blood flow rate through leptomeningeal anastomoses. In view of the retrograde direction of collateral blood flow into the middle cerebral artery territory, we developed parasagittal laser-Doppler flowmetry. Using this method two laser-Doppler probes are placed on the cerebral cortex: probe 1 is placed near the anastomoses between the middle- and anterior cerebral artery, probe 2 is placed 2 mm further away from these anastomoses than probe 1. We found in both rat strains a comparable relation between the areas under the curve of the signal measured by both laser-Doppler probes for 2 h after middle cerebral artery occlusion. This relation is considered to be a measurement of the collateral blood flow rate into the middle cerebral artery territory through leptomeningeal anastomoses after middle cerebral artery occlusion. We conclude that collateral blood flow for the two strains were essentially similar for the initial 2 h after MCA occlusion. Although these collateral blood flows could have been different at a later time, it is unlikely that the interstrain difference in cerebral infarction volume between Wistar and Fischer-344 rats after proximal middle cerebral artery occlusion is caused by an apparent interstrain difference in the magnitude of collateral blood flow rate through leptomeningeal anastomoses. The parasagittal laser-Doppler flowmetry technique we developed for these experiments is currently successfully used in our laboratory to evaluate the efficacy of hemodynamically active pharmacotherapeutical agents in raising the collateral blood flow rate into the middle cerebral artery territory after middle cerebral artery occlusion.     

Techniques to improve physicians' use of diagnostic tests: a new conceptual framework

OBJECTIVES: To review the published literature on interventions aimed at improving physicians' testing practices and propose methodologic standards for these studies and to review selected studies using the PRECEDE framework, a behavioral model that helps categorize interventions based on which behavioral factors are being affected. DATA SOURCES: MEDLINE, EMBASE, and HEALTHStar databases were searched for the years 1966 to January 1, 1998, for English-language articles pertaining to diagnostic testing behavior; bibliographies were scanned to identify articles of potential interest; and researchers in health services, health behavior, and behavior modification were contacted for proprietary and other unpublished articles. STUDY SELECTION: A total of 102 articles were identified that described the results of interventions aimed at changing physicians' testing practices. We included the 49 studies that compared diagnostic testing practices in intervention and control groups. DATA EXTRACTION: Two investigators independently reviewed each article in a blinded fashion using a standard data collection form to obtain a methodologic score and to abstract the key elements of each intervention. DATA SYNTHESIS: On a 38-point methodologic criteria scale, the mean +/- SD score was 13+/-4.4. The desired behavior change was reported in the intervention group in 37 (76%) of 49 studies. Twenty-four (86%) of 28 interventions targeted at many behavioral factors were successful, while 13 (62%) of 21 studies aimed at a single behavioral factor were successful (P=.12). CONCLUSIONS: A majority of interventions to improve physicians' testing practices reported in the literature claimed success, with interventions based on multiple behavioral factors trending toward being more successful. While methodologic flaws hamper drawing strong conclusions from this literature, application of a behavioral framework appears to be useful in explaining interventions that are successful and can facilitate interpretation of intervention results.     

Distinctive morphological features of a subset of cortical neurons grown in the presence of basal forebrain neurons in vitro

Basal forebrain cholinergic neurons (BFCNs) provide the major subcortical source of cholinergic input to cerebral cortex and play an important role in regulating cortical activity. The present study examined the ability of BFCNs to influence neocortical neuronal growth by examining effects of the presence of BFCNs on certain cortical neurons grown under the controlled conditions of dissociated cell culture. Initial experiments demonstrated distinctive morphological features of a population of neurons (labeled with SMI-32, a monoclonal antibody to nonphosphorylated neurofilament proteins that labels pyramidal neurons in vivo) in cocultures containing basal forebrain (BF) and cortical cells. These neurons (large neurons immunoreactive for SMI-32 [SMI-32(+) neurons]) were characterized as having extensive axons, greater soma size, and more dendritic growth than did most SMI-32(+) neurons in the cultures. Staining for SMI-32 in cocultures in which the cortical neurons were labeled with a fluorescent marker before adding the BF cells indicated that virtually all large SMI-32(+) neurons were of cortical origin. Eliminating BFCNs with the selective cholinergic immunotoxin 192 IgG-saporin resulted in a >80% decrease in the number of large SMI-32(+) neurons, although causing little damage to other cells in the treated cultures; this suggests that survival or maintenance of large SMI-32(+) neurons may depend on ongoing trophic support from BFCNs. Thus, present findings suggest that BFCNs may provide powerful growth- and/or survival-enhancing signals to a subset of cortical neurons.     

P450c17 mutations R347H and R358Q selectively disrupt 17,20-lyase activity by disrupting interactions with P450 oxidoreductase and cytochrome b5

The lacZ-hobH fusion clone, containing an Escherichia coli DNA segment located at 92 min on the chromosomal map, was screened as a producer of E. coli oriC hemi-methylated binding activity. We have purified the protein encoded by this locus to near homogeneity. The protein corresponds to the monomeric form of a non-specific acid phosphatase (NAP) whose gene has been designated aphA. oriC DNA footprinting experiments showed protection of hemi-methylated probe by partially purified NAP, but not by purified preparations. Yet, gel retardation experiments with an oriC oligonucleotide demonstrated DNA binding activity of purified NAP in the presence of Mg2+. This experiment also showed an increased affinity of the protein for the hemi-methylated probe compared with the fully or unmethylated form. Indirect immunofluorescene microscopy revealed the existence of discrete NAP foci at mid-cell in cells with two nucleoids, but at cell poles in those with one nucleoid.     

Twice-daily compared with once-daily thoracic radiotherapy in limited small-cell lung cancer treated concurrently with cisplatin and etoposide

BACKGROUND: For small-cell lung cancer confined to one hemithorax (limited small-cell lung cancer), thoracic radiotherapy improves survival, but the best ways of integrating chemotherapy and thoracic radiotherapy remain unsettled. Twice-daily accelerated thoracic radiotherapy has potential advantages over once-daily radiotherapy. METHODS: We studied 417 patients with limited small-cell lung cancer. All the patients received four 21-day cycles of cisplatin plus etoposide. We randomly assigned these patients to receive a total of 45 Gy of concurrent thoracic radiotherapy, given either twice daily over a three-week period or once daily over a period of five weeks. RESULTS: Twice-daily treatment beginning with the first cycle of chemotherapy significantly improved survival as compared with concurrent once-daily radiotherapy (P=0.04 by the log-rank test). After a median follow-up of almost 8 years, the median survival was 19 months for the once-daily group and 23 months for the twice-daily group. The survival rates for patients receiving once-daily radiotherapy were 41 percent at two years and 16 percent at five years. For patients receiving twice-daily radiotherapy, the survival rates were 47 percent at two years and 26 percent at five years. Grade 3 esophagitis was significantly more frequent with twice-daily thoracic radiotherapy, occurring in 27 percent of patients, as compared with 11 percent in the once-daily group (P<0.001). CONCLUSIONS: Four cycles of cisplatin plus etoposide and a course of radiotherapy (45 Gy, given either once or twice daily) beginning with cycle 1 of the chemotherapy resulted in overall two- and five-year survival rates of 44 percent and 23 percent, a considerable improvement in survival rates over previous results in patients with limited small-cell lung cancer.     

Reconstruction of total maxillectomy defects with preservation of the orbital contents

Reconstruction after total maxillectomy with preservation of the orbital contents is technically more challenging than when the maxillectomy is combined with orbital exenteration. Reconstruction of such defects should (1) provide support to the orbital contents, (2) obliterate any communication between the orbit and nasopharynx, (3) reconstruct the palatal surface, and (4) achieve facial symmetry and a good aesthetic result. We report our experience in performing reconstructive surgery on 14 patients who had a total maxillectomy and preservation of the orbital contents using nonvascularized bone grafts for reconstruction of the orbital floor and maxilla, in conjunction with a soft-tissue free flap or pedicled muscle flap. The orbital floor was reconstructed using split ribs in six cases (42.9 percent), split calvaria in six cases (42.9 percent), and iliac crest graft in two cases (14.3 percent). A myocutaneous rectus abdominis free flap was used for soft-tissue reconstruction and resurfacing of the palatal mucosa in twelve patients (85.7 percent), and a temporalis muscle transposition was used in two elderly patients (14.3 percent). One patient died 2 days after surgery. Mean follow-up and aesthetic and functional results were assessed in the remaining 13 patients a minimum of 6 months postoperatively. In 9 of these 13 patients (69.2 percent), postoperative radiotherapy was administered. No reexplorations or free flap failures were observed. One rectus flap developed partial necrosis of the skin island intraorally without affecting the final result. All patients had adequate functional vision. One patient had a mild vertical dystopia; there were no cases of enophthalmos. Ectropion was the most common undesirable result and was present in 10 of 13 cases (76.9 percent). It was graded as mild in four cases (40.0 percent), moderate in four cases (40.0 percent), and severe in the remaining two cases (20.0 percent). Speech was considered normal in six cases (46.2 percent), near normal in six cases (46.2 percent), and intelligible in one case (7.7 percent). Chewing function was considered good (soft to unrestricted diet) in all cases except for one patient who was only able to eat a pureed diet. Aesthetic results after immediate reconstruction were considered good in nine cases (69.2 percent) and fair in four cases (30.8 percent). Primary reconstruction of total maxillectomy defects with orbital content preservation remains a complex problem without a perfect solution. The combination of nonvascularized bone grafts for orbital/maxillary reconstruction with a soft-tissue free flap is a safe, reliable, and effective method of maximizing postoperative functional and aesthetic results.     

Help seeking for mental health care among poor Puerto Ricans: problem recognition, service use, and type of provider

OBJECTIVES: This study examines the effects of health, predisposing, and enabling factors on recognition of a mental health problem, use of formal mental health care, and contact with a specialized mental health provider. METHODS: Interviews were conducted with a probability sample of 3,435 adults. The variables examined include measures of mental health; social and demographic factors; and enabling factors relevant to the help-seeking process. RESULTS: Subjective and objective measures of mental health were associated with the recognition of a mental health problem. The objective assessment of definite need for services was relevant for the use of formal services. However, the subjects' perception of poor mental health was strongly related to receiving care from a mental health specialist. Although interaction with social networks is associated with use of formal services, low economic strain is related to receiving care from the specialty sector. CONCLUSIONS: The results support the importance of using multiple measures of mental health problems. The finding that individuals' perceived economic strain increases the likelihood of receiving specialized care suggests that studies of economic barriers to the use of mental health services might benefit from the adoption of measures that assess perceived economic circumstances.