Processing of cdk5 activator p35 to its truncated form (p25) by calpain in acutely injured neuronal cells

Recently, it was shown that conversion of cdk5 activator protein p35 to a C-terminal fragment p25 promotes a deregulation of cdk5 activity, which may contribute to neurodegeneration in Alzheimer's disease. In this study, we present evidence that calpain is a protease involved in the conversion of p35 to p25. To activate calpain, rat cerebellar granule neurons were treated with maitotoxin (MTX). A C-terminus-directed anti-p35 antibody detected that p35 conversion to p25 paralleled the formation of calpain-generated alpha-spectrin (alpha-fodrin) breakdown products (SBDP's) in a maitotoxin-dose-dependent manner. Two calpain inhibitors (MDl28170 and SJA6017) reduced p35 processing but were unchanged when exposed to the caspase inhibitor carbobenzoxy-Asp-CH(2)OC(=O)-2, 6-dichlorobenzene or the proteasome inhibitors (lactacystin and Z-Ile-Glu(OtBu)Ala-Leu-CHO). p35 protein was also degraded to p25 when rat brain lysate was subjected to in vitro digestion with purified mu- and m-calpains. Additionally, in a rat temporary middle cerebral artery occlusion model, p35 processing to p25 again paralleled SBDP formation in the ischemic core. Lastly, in malonate-injured rat brains, the ipsilateral side showed a striking correlation of SBDP formation with p35 to p25 conversion and tau phosphorylation (at Ser202 and Thr205) increase. These data suggest that calpain is a major neuronal protease capable of converting p35 to p25 and might play a pathological role of activating cdk5 and its phosphorylation of tau in Alzheimer's disease.

Osteomyocutaneous flap as a preclinical composite tissue allograft: swine model

Composite tissue allotransplantation (CTA) constitutes one of the last frontiers of microsurgery. Prior to its clinical application, the long-term efficacy of modern immunotherapy must be tested in a pre-clinical CTA model. Based on the concept of osteomyocutaneous forearm flap, we developed a CTA flap model in swine. After identifying the vascular territory of the flaps in six pigs (vascular casting), flaps were transplanted from mismatched donor to recipient pigs (n = 6). Rejection was assessed daily by visual inspection and histopathology of biopsy specimens. Recipient pigs were able to ambulate immediately following surgery. There were no flap failures owing to technical or surgical complications. Rejection occurred over a period of 7 days as manifested by edema, cellular infiltration, epidermalysis, and thrombosis. This pre-clinical flap model is excellent for evaluating the effectiveness of modern immunotherapy because it is anatomically and immunologically relevant and because the minimal morbidity caused to the animal permits long-term studies.

[The preparation of electric arc method and spectral analysis on long persistence luminescent chinaware of SrAl2O4:Eu2+]

Luminescent chinaware of long persistence of SrAl2O4:Eu2+ has been prepared with using are method. Fluorescence and excitation spectra were measured in order to study its luminescence and long persistence properties. Results show that both of luminescent chinaware and polycrystalline powdered phosphor are the same in luminescence decay and consist of an initial fast process and a later extremely slow process. Long persistence properties of luminescent chinaware are better more than polycrystalline powdered phosphor, and its function of environment-resistant has been improved prominently.

[Mobilization of autologous peripheral blood stem cells by chemotherapy and recombinant granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF)]

OBJECTIVE

To observe the efficacy of chemotherapy and recombinant granulocyte colony-stimulating factor (G-CSF, Glycosylated) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in autologous peripheral blood stem cells (APBSC) mobilization.

METHODS

The mobilization regimen: CBP 350 mg/m(2) intravenously injected at day 1, Vp16 350 mg/m(2) intravenously injected from day 1 to day 3. G-CSF and GM-CSF 5 microg x kg(-1) x d(-1) each, subcutaneously injected and DXM 5 mg/d intramuscularly injected, from the day of white blood cell (WBC) recovery to (2.4 - 6.4) x 10(9)/L from nadir to the day before the end of APBSC harvesting. APBSC harvesting started when WBC > 20.0 x 10(9)/L and ended when accumulated mononuclear cells (MNC) > 5 x 10(8)/kg. CFU-GM assay and CD(34)(+) cells counting of the APBSC were performed.

RESULTS

Twenty cases underwent APBSC mobilization. APBSC harvest began at day 22.15 +/- 3.66 for two successive days. Accumulated MNC was (5.93 +/- 1.62) x 10(8)/kg, CD(34)(+) cells (23.10 +/- 11.53) x 10(6)/kg and CFU-GM (3.44 +/- 2.85) x 10(5)/kg. No severe toxicity was observed. Hematopoiesis was well reconstituted in 8 patients received single and in 1 patient received double APBSC transplantations.

CONCLUSION

Chemotherapy combined with G-CSF + GM-CSF was a safe and highly effective method for APBSC mobilization.

Distinctions between bovine herpesvirus 1 and herpes simplex virus type 1 VP22 tegument protein subcellular associations

The alphaherpesvirus tegument protein VP22 has been characterized with multiple traits including microtubule reorganization, nuclear localization, and nonclassical intercellular trafficking. However, all these data were derived from studies using herpes simplex virus type 1 (HSV-1) and may not apply to VP22 homologs of other alphaherpesviruses. We compared subcellular attributes of HSV-1 VP22 (HVP22) with bovine herpesvirus 1 (BHV-1) VP22 (BVP22) using green fluorescent protein (GFP)-fused VP22 expression vectors. Fluorescence microscopy of cell lines transfected with these constructs revealed differences as well as similarities between the two VP22 homologs. Compared to that of HVP22, the BVP22 microtubule interaction was much less pronounced. The VP22 nuclear interaction varied, with a marbled or halo appearance for BVP22 and a speckled or nucleolus-bound appearance for HVP22. Both VP22 homologs associated with chromatin at various stages of mitosis and could traffic from expressing cells to the nuclei of nonexpressing cells. However, distinct qualitative differences in microtubule, nuclear, and chromatin association as well as trafficking were observed. The differences in VP22 homolog characteristics revealed in this study will help define VP22 function within HSV-1 and BHV-1 infection.

[Comparative study of three common G6PD gene mutations in Yao and Han People in Guangxi]

OBJECTIVE

To study G6PD gene mutation diversity in Yao and Han people in Guangxi and compare the genotypic frequencies.

METHODS

The three common G6PD gene mutations in Chinese were investigated in 34 G6PD deficient individuals from Yao and 37 from Han people by using an amplification refractory mutation system (ARMS).

RESULTS

Among 34 cases of G6PD deficiency of Yao people, the genotypic frequencies of G1376T, G1388A and A95G were 41.2%, 26.5% and 14.7%, respectively. A case of C1311T was detected. As compared with that in Han people, the respective frequencies were 16.2%, 40.6% and 5.4%.

CONCLUSION

The main G6PD mutations in Yao people were the same with Han people in Guangxi, but G1376T mutation was higher than that in Han people. The C1311T mutation in Yao people in Guangxi was reported for the first time.

[Influence of the administrators of family planning on the spread of norplant in countryside of Sichuan]

The purpose of the study was to understand the family planning administrators' knowledge of Norplant and their fluence on the spread of Norplant in countryside of Sichuan. 156 administratoras were surveyed. It was found that most of the administrators worked hard on education, propagation, organization and management of using Norplant, and they recognized the contraceptive efficacy of Norplant. However, the educational level of the administrators was generally low. They were short of the training on Norplant related knowledge(training rate was only 36.5%). The degree of the users' satisfaction and the administrators' knowledge on Norplant varied between areas. The result indicated that the basic quality of the administrators and their knowledge of Norplant were influences on the spread of Norplant in the countryside of Sichuan. Soit is very important to improve the basic quality and knowledge of the administrators of family planning.

Somatic mutations of the PPP2R1B candidate tumor suppressor gene at chromosome 11q23 are infrequent in ovarian carcinomas

Previous studies have demonstrated frequent allelic losses of distal chromosome 11q in ovarian carcinomas. The tumor suppressor gene(s) presumably targeted by these losses have not yet been identified. PPP2R1B is a candidate tumor suppressor gene at 11q23 that has recently been shown to be mutated in a subset of colorectal and lung cancers. We evaluated 5 ovarian carcinoma cell lines and 27 primary ovarian carcinomas for allelic losses of 11q23 and for mutations in the open reading frame of PPP2R1B. We also evaluated the primary tumors for allelic losses at 17p13, another chromosomal region frequently affected by losses of heterozygosity (LOH) in ovarian cancers. 11q23 and 17p13 allelic losses were identified in 25% and 74% of the carcinomas, respectively. No mutations within PPP2R1B coding sequences were found. These findings indicate that mutations of the PPP2R1B gene are infrequent in ovarian cancer and that deletions affecting the distal portion of chromosome 11q in ovarian cancer likely target inactivation of other genes.

[Epstein-Barr virus infection and expression of T-cell intracellular antigen-1 (TIA-1) in intestinal T-cell lymphoma]

OBJECTIVE

To study the status of Epstein-Barr virus (EBV) infection and the expression of TIA-1 antigen in 24 cases of intestinal T-cell lymphomas.

METHODS

In situ hybridization for EBER1/2; immunohistochemical staining by three step ABC technique for TIA-1, LMP-1, CD30, CD45RO, CD3 AND CD20. 19 cases of intestinal B-cell lymphomas were used for comparison.

RESULTS

(1) Of the 24 intestinal T-cell lymphoma cases, 23 were pleomorphic, medium to large cell type, and one cases was small cell type; in 20 of the 24 cases EBER1/2 signals were detected in the tumor cells; in 4 of the 20 EBER1/2 positive cases, tumor cells expressed LMP-1; EBER1/2 was not detected in 19 cases of intestinal B-cell lymphomas. (2) in 23 of the 24 cases, TIA-1 was expressed in most tumor cells, but not in the only case of small cell type; TIA-1 was negative in tumor cells of all 19 cases of intestinal B-cell lymphomas.

CONCLUSIONS

A high level of EBV infection was present in this group of intestinal T-cell lymphomas, the expression of TIA-1 may be related to its cell origin. Intestinal T-cell lymphoma may be an EBV-associated extranodal NK/T cell lymphoma.

Molecular characterization of radiation- and chemically induced mutations associated with neuromuscular tremors, runting, juvenile lethality, and sperm defects in jdf2 mice

The juvenile development and fertility-2 (jdf2) locus, also called runty-jerky-sterile (rjs), was originally identified through complementation studies of radiation-induced p-locus mutations. Studies with a series of ethylnitrosourea (ENU)-induced jdf2 alleles later indicated that the pleiotropic effects of these mutations were probably caused by disruption of a single gene. Recent work has demonstrated that the jdf2 phenotype is associated with deletions and point mutations in Herc2, a gene encoding an exceptionally large guanine nucleotide exchange factor protein thought to play a role in vesicular trafficking. Here we describe the molecular characterization of a collection of radiation- and chemically induced jdf2/Herc2 alleles. Ten of the 13 radiation-induced jdf2 alleles we studied are deletions that remove specific portions of the Herc2 coding sequence; DNA rearrangements were also detected in two additional mutations. Our studies also revealed that Herc2 transcripts are rearranged, not expressed, or are present in significantly altered quantities in animals carrying most of the jdf2 mutations we analyzed, including six independent ENU-induced alleles. These data provide new molecular clues regarding the wide range of jdf2 and p phenotypes that are expressed by this collection of recently generated and classical p-region mutations.

Truncation of the C terminus of the rat brain Na(+)-Ca(2+) exchanger RBE-1 (NCX1.4) impairs surface expression of the protein

The C terminus of the rat brain Na(+)-Ca(2+) exchanger (RBE-1; NCX1. 4) (amino acids 875-903) is modeled to contain the last transmembrane alpha helix (amino acids 875-894) and an intracellular extramembraneous tail of 9 amino acids (895-903). Truncation of the last 9 C-terminal amino acids, Glu-895 to stop, did not significantly impair functional expression in HeLa or HEK 293 cells. Truncation, however, of 10 amino acids (Leu-894 to stop; mutant C10) reduced Na(+) gradient-dependent Ca(2+) uptake to 35-39% relative to the wild type parent exchanger, and further truncation of 13 or more amino acids resulted in expression of trace amounts of transport activity. Western analysis indicated that Na(+)-Ca(2+) exchanger protein was produced whether transfection was carried out with functional or non-functional mutants. Immunofluorescence studies of HEK 293 cells expressing N-Flag epitope-tagged wild type and mutant Na(+)-Ca(2+) exchangers revealed that transport activity in whole cells correlated with surface expression. All cells expressing the wild type exchanger or C9 exhibited surface expression of the protein. Only 39% of the cells expressing C10 exhibited surface expression, and none was detected in cells transfected with non-functional mutants C13 and C29. Since functional and non-functional mutants were glycosylated, the C terminus is not mandatory to translocation into the endoplasmic reticulum (ER). Endoglycosidase H digestion of [(35)S]methionine-labeled protein derived from wild type Na(+)-Ca(2+) exchanger and from C10 indicated that resistance to the digestion was acquired after 1 and 5 h of chase, respectively. C29 did not acquire detectable resistance to endoglycosidase H digestion even after 10 h of chase. Taken together, these results suggest that the "cellular quality control machinery" can tolerate the structural change introduced by truncation of the C terminus up to Ser-893 albeit with reduced rate of ER-->Golgi transfer and reduced surface expression of the truncated protein. Further truncation of C-terminal amino acids leads to retention of the truncated protein in the ER, no transfer to the Golgi, and no surface expression.

Long-term survival of an extremity composite tissue allograft with FK506-mycophenolate mofetil therapy

BACKGROUND

High-dose tacrolimus (FK506) monotherapy has significantly prolonged rat hindlimb allograft survival. With an eye toward direct clinical application, we used a large-animal extremity composite tissue allograft model to assess the antirejection efficacy and systemic toxicity of combination FK506-mycophenolate mofetil (MMF) treatment.

METHODS

Radial forelimb osteomyocutaneous flap transplants were performed between size-matched outbred pigs assigned to one of two groups: 5 control pigs received no immunosuppression and 9 animals received a once-daily oral FK506-MMF-prednisone regimen. Rejection was assessed by visual inspection of flap skin and was correlated with serial histopathologic examination of skin biopsy specimens.

RESULTS

In all control pigs the flap was completely rejected on day 7. Of the 9 pigs receiving treatment, 3 died from pneumonia on days 29, 30, and 83 without signs of rejection and another died from gastric rupture on day 42 with persistent mild rejection. The remaining 5 animals were free of rejection at the end of the 90-day follow-up period (P < 0.005 vs controls). Overall, 5 pigs had pneumonia, 4 septic arthritis, 3 toe abscesses, and 5 diarrhea and decreased weight gain.

CONCLUSIONS

Combination oral FK506-MMF treatment provided a superior antirejection effect but more produced more toxicity than that previously demonstrated with cyclosporin A-MMF therapy in our model. Our results suggest that reduction of FK506 or MMF doses might decrease both infectious and drug-specific side effects while still providing adequate prophylaxis against rejection.

Scoring of skin rejection in a swine composite tissue allograft model

BACKGROUND

For the first time, we define and correlate visual and histologic grading systems of composite tissue allograft (CTA) skin rejection in a large-animal model and determine the utility of these grading systems for early diagnosis and monitoring of rejection.

MATERIALS AND METHODS

Sixteen pairs of outbred swine underwent transplant of a forelimb osteomyocutaneous free flap. Group I (n = 6) did not receive immunosuppressive therapy. Group II (n = 10) received oral cyclosporin A, mycophenolate mofetil, and prednisone. The flap was visually inspected and protocol skin biopsies were taken at frequent intervals over a 90-day period. Visual Grades 0 (no rejection) to 4 (severe rejection) were assigned based on skin color, bleeding from biopsy site, and blister formation. Histologic Grades 0 to 4 were assigned based on the degree of vasculitis, folliculitis, dermal inflammation, and epidermal degeneration present.

RESULTS

All Group I animals progressively rejected their graft by Day 7. Group II grafts survived from 19 and 90 days; 93% of 115 biopsy specimens were read to be within +/-1 histologic score of their assigned flap visual grade. Visual assessment carried an 8% false positive and 39% false negative rate with regard to biopsy-proven rejection. However, 81% of missed rejection specimens were histologic Grade 1. Biopsy, when visually indicated, would detect all rejection episodes when histologically Grade 1 or 2 and still potentially reversible.

CONCLUSIONS

Visual scoring of CTA skin serves as a useful tool for initially detecting rejection, but repeated histologic evaluation is necessary for monitoring the subsequent course of the graft.

Detection of the most common G6PD gene mutations in Chinese using amplification refractory mutation system

Glucose-6-phosphate dehydrogenase (G6PD) is the most common human enzymopathy. To date more than 122 mutations in the G6PD gene have been discovered, among which 12 point mutations are found in the Chinese. The 2 most common mutations, G1388A and G1376T, account for more than 50% of mutations representing various regions and ethnic groups in China. Setting up a simple and accurate method for detecting these mutations is not only useful for studying the frequency of the G6PD genotypes, but also for finding new mutations. The purpose of this study was to find a simple, inexpensive and accurate method for detecting these common mutations. The amplification refractory mutation system (ARMS) method was used in this study. Samples from 28 G6PD-deficient males were investigated. The natural and mismatched amplification and restriction enzyme digestion method was used as a standard method to evaluate the nature of the point mutations. Sixteen cases were found carrying the G1388A mutation and 12 the G1376T mutation. Fourteen cases of G1388A and 10 cases of G1376T were confirmed by ARMS. Four cases were not in concordance with the results obtained by the mismatched amplification-restriction enzyme digestion. These 4 cases were then judged by direct PCR sequencing at exon 12. The DNA sequencing data supported the results obtained by ARMS. Thus we concluded that the ARMS is a rapid, simple, inexpensive and accurate method for detecting the most common G6PD gene mutations among the Chinese.

Pharmacokinetic advantage of intra-arterial cyclosporin A delivery to vascularly isolated rabbit forelimb. I. Model development

Effective antirejection therapy with minimal systemic morbidity is required if limb transplantation is to become a clinical reality. We investigated whether i.a. infusion of cyclosporin A (CSA) into the vascularly isolated rabbit forelimb will distribute drug homogeneously to the tissues and produce higher local drug levels than same-dose i.v. treatment, thereby improving the therapeutic index. CSA 4.0 mg/kg/day was infused continuously via osmotic minipump into either the right brachial artery (i.a. group) or jugular vein (i.v. group) of New Zealand rabbits. Ligation of all muscles at the right mid-arm level was performed in the i.a. group to eliminate collateral circulation and simulate allografting, while leaving bone and neurovasculature intact. On day 6, CSA concentrations were measured in skin, muscle, bone, and bone marrow samples taken from different compartments of the right and left forearms in the i.a. group and right forearm only in the i.v. group. There were no significant differences between compartmental CSA levels in all tissues examined on the locally treated, right side during i.a. infusion, indicating that drug streaming from the catheter tip is not occurring in our model. During i.a. infusion, mean CSA concentrations were 4- to 7-fold higher in the right limb than in the left limb in all four tissues examined. Tissue CSA levels in the left limb were equivalent to those achieved during i.v. infusion, but CSA concentrations in blood, kidney, and liver were higher during i.a. infusion. These favorable, preliminary, single-dose pharmacokinetic results warrant further investigation in our novel rabbit model.

Perspectives of pharmacotherapy in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of progressive decline of cognitive function in aged humans, and it is characterized by the presence of numerous senile plaques and neurofibrillary tangles accompanied by neuronal loss. The senile plaques are composed of amyloid beta-peptides (A beta), 40-42 amino acid peptide fragments of the beta-amyloid precursor protein. Genetic, molecular biological and neuropharmacological evidence support the 'amyloid cascade hypothesis' for the pathogenesis of the disease. We review the in vivo effects of various compounds on behavioral and neuropathological changes in the non-transgenic animal models of AD produced by continuous i.c.v. infusion of A beta. These results support therapeutic strategies such as cholinergic therapy, anti-inflammatory agents, antioxidants and estrogen replacement therapy, as well as other cognition enhancers for the treatment of AD. In addition, the amyloid cascade hypothesis offers a number of potential targets for novel therapeutic strategies in AD. We believe that our non-transgenic animal model, as well as transgenic animal models, are useful for developing novel pharmacotherapeutics in AD.

[Genetic linkage of polymorphisms of type I angiotensin II receptor gene to Chinese Han hypertension]

OBJECTIVE

To observe the CA repeat polymorphism of the type I angiotensin II receptor gene on Chinese Han people, and evaluate the genetic linking to hypertension.

METHODS

The CA repeat polymorphism at 3'-flanking region of AT1R gene was studied by amplified fragment length polymorphism (Amp-FLP ) in Chinese Han people from Shandong and Xi'an.

RESULTS

There were 9 alleles ranging from 130bp to 146bp in all subjects. The allele frequencies were 0.01 to 0.38, and allele A4 was more frequent in the control. The heterozygosity of CA repeat locus was 0.789, the polymorphic information content, 0.746. There was no significant difference in distribution of CA repeat polymorphism genotype between different regions in same ethnic (P>0. 05), but the allele frequency of CA repeat polymorphism in hypertensive group was significantly different from that of control (P<0.05). There was no detectable distortion from Hardy-Weinberg equilibrium in both groups.

CONCLUSION

The results suggest that CA repeat polymorphism of AT1R gene be associated with Chinese Han hypertensive people.

[Studies on a G6PD polymorphic site, cDNA C1311T]

OBJECTIVE

To use amplification refractory mutation system(ARMS) method to detect the G6PD cDNA C1311T mutation, estimate its frequency in a normal south Chinese population, and investigate whether IVS-11 C93T mutation is the cause of certain G6PD deficient cases.

METHODS

DNA sequencing was used to confirm the C1311T and the IVS-11 C93T mutations. ARMS was set up to detect the C1311T and to estimate its frequency.

RESULTS

Three cases of C1311T mutation were found in 40 G6PD deficient samples. The optimal condition for ARMS was established. Using this method, 19 cases of C1311T were detected in 103 normal men, and the frequency of this polymorphic mutation was estimated to be 18.4% in southern Chinese population. Four cases with G6PD deficiency were demonstrated to be C at the IVS-11 93 position. At the same time, a case of IVS-11 93 C-->T was found in a normal man.

CONCLUSIONS

ARMS is a simple, time-saving, and reliable method for detecting known G6PD gene point mutation. The frequency of C1311T in a normal south Chinese population is 18.4%. IVS-11 C93T might be another polymorphic site of the G6PD gene, and it is not the cause of enzyme deficiency in certain G6PD deficient cases.

[Detection of three common G6PD gene point mutations in Guangdong province by using ARMS]

OBJECTIVE

To detect three common G6PD gene point mutations, G1388A, G1376T and A95G, in Guangdong province and to estimate the approximate frequencies.

METHODS

Using the amplification refractory mutation system(ARMS) method to detect G1388A and G1376T and the newly developed ARMS to identify A95G mutation.

RESULTS

Ninety cases of G6PD deficient male were examined, and 42 of them were identified to be G1388A(46.7%), 14 G1376T(15.6%), and 12 A95G(13.3%). Totally 68 out of the 90 cases(75.6%) were of the three common mutations. The rest belong to rare or undefined mutations.

CONCLUSION

ARMS method can be used in detecting common mutations of G6PD gene with the benefits of simple, fast, economic, and accurate.

Ventilatory responses to hypercapnia and hypoxia after 6 h passive hyperventilation in humans

1. Acute exposure to hypoxia stimulates ventilation and induces hypocapnia. Long-term exposure to hypoxia generates changes in respiratory control known as ventilatory acclimatization to hypoxia. The object of this study was to investigate the degree to which the hyperventilation and hypocapnia can induce the changes known as ventilatory acclimatization to hypoxia, in the absence of the primary hypoxic stimulus itself. 2. Three 6 h protocols were each performed on twelve healthy volunteers: (1) passive hypocapnic hyperventilation, with end-tidal CO2 pressure (PET,CO2) held 10 Torr below the eupnoeic value; (2) passive eucapnic hyperventilation, with PET,CO2 maintained eucapnic; (3) control. 3. Ventilatory responses to acute hypercapnia and hypoxia were assessed before and half an hour after each protocol. 4. The presence of prior hypocapnia, but not prior hyperventilation, caused a reduction in air-breathing PET,CO2 (P < 0.05, ANOVA), and a leftwards shift of the ventilatory response to hypercapnia (P < 0.05). The presence of prior hyperventilation, but not prior hypocapnia, caused an increase in the ventilatory sensitivity to CO2 (P < 0.05). No significant effects of any protocol were detected on the ventilatory sensitivity to hypoxia. 5. We conclude that following 6 h of passive hyperventilation: (i) the left shift of the VE-PET,CO2 relationship is due to alkalosis and not to hyperventilation; (ii) the increase in slope of the VE-PET,CO2 relationship is due to the hyperventilation and not the alkalosis; and (iii) ventilatory sensitivity to hypoxia is unaltered.

[Study on electrochemical behavior of HL-60 cells during the etoposide-inducing apoptosis]

OBJECTIVE

To study the electrochemical behavior of apoptotic HL-60 cells induced with etoposide.

METHODS

Electrochemical cytosensor was used to monitor HL-60 cells treated with etoposide.

RESULTS

The peak current and electron transfer rate decreased as etoposide dosage increased. The decrease appeared at 2 micrograms/ml etoposide treatment and was remarkable at 20 micrograms/ml, which occurred before the typical changes of cell morphology and DNA contents for apoptosis. FCM-DNA analysis showed that the apoptotic cells were of 10.5%-20% while the peak current decreased from 1.8 microA to 0.4 microA after 2.3 and 4 hours treatment with 200 micrograms/ml etoposide, and the peak current after 4 hours treatment was 5 times lower than that before induction.

CONCLUSION

The changes of electrochemical behavior during the early stage of apoptosis occurred earlier and could be accumulated.

Long-term composite tissue allograft survival in a porcine model with cyclosporine/mycophenolate mofetil therapy

BACKGROUND

Low-dose cyclosporine (CsA)/mycophenolate mofetil (MMF) therapy has significantly reduced the frequency of rejection and drug-induced side effects in rat hindlimb allograft recipients. With an eye toward direct clinical application, we developed a large-animal extremity composite tissue allograft model to assess the antirejection efficacy and systemic toxicity of combination CsA/MMF treatment.

METHODS

Radial forelimb osteomyocutaneous flap transplants were performed between size-matched, outbred pigs assigned to one of two groups: 5 control pigs received no immunosuppression, and 10 pigs received a once-daily oral CsA/MMF/prednisone regimen. Rejection was assessed by visual inspection of flap skin and correlated with serial histopathologic examination of skin biopsies.

RESULTS

In all control pigs, the flap was completely rejected on day 7. Of the 10 pigs receiving treatment, one died from pneumonia and an another from an anesthetic complication on days 19 and 30, respectively, without signs of rejection. Two flaps were lost on days 25 and 29 from severe rejection. Three pigs were free of rejection at the end of the 90-day follow-up period, and three had stable mild-to-moderate rejection at 90 days (P= 0.0007 vs. controls). White blood cell and platelet counts, serum creatinine values, and liver function tests remained normal in all animals receiving immunosuppressive therapy.

CONCLUSIONS

Our results, to our knowledge, demonstrate for the first time that rejection can be significantly delayed in a large-animal composite tissue allograft model including skin using only orally administered agents dosed according to clinically relevant strategies without significant drug-specific systemic side effects.

Muscular urinary sphincter: electrically stimulated myoplasty for functional sphincter reconstruction

PURPOSE

To reconstruct an electrically stimulated muscular urinary sphincter (MUS) using a tailored gracilis muscle free flap with intact nerve.

MATERIALS AND METHODS

Unilateral surgically tailored gracilis muscle free flaps were transferred into the pelvis in eight dogs, leaving the obturator nerve intact. The muscle's pedicle vessels were anastomosed to the inferior epigastric artery and vein in the pelvis and the muscle was wrapped around the bladder neck. Electrodes were inserted into the MUS and connected to a programmable pulse generator. After 8 weeks of training the MUS, the pulse generator was programmed to be "on" for 4 hours and "off' for 15 minutes in a continuous cycle. Urodynamic studies were performed periodically, and at the end of the experiment the MUS and proximal urethra were harvested for histology. Three control dogs had sham operations.

RESULTS

All MUS's functioned well following the procedure. Histology of the MUS/urethra complex showed no evidence of stricture. Except for one dog, all urethras were easily catheterized.

CONCLUSIONS

This electrically stimulated innervated free-flap MUS technique effectively increases bladder outlet resistance without producing urethral obstruction.

[Study on nuclear matrix protein in leukemia cells]

OBJECTIVE

To compare the composition of nuclear matrix proteins (NMP) between leukemia cells and normal bone marrow cells.

METHODS

NMP was isolated by high-salt extration and identified by SDS-PAGE and western blotting.

RESULTS

Increase in NMP was demonstrated in acute and chronic myelogenous leukemic cells as well as in the blast phase of chronic leukemia. On SDS-PAGE, NMPs with molecular weight different from what were seen in normal bone marrow cells were present in both acute and chronic myelogenous leukemias.

CONCLUSION

Marked changes of NMP, not only in contents but also in compositions, exist in leukemic cells compared with normal bone marrow cells. NMP may serve as a target of chemotherapeutic drugs against leukemia.

[Isolation and identification of active constituent of Toddalia asiatica in cardiovascular system]

The ethereal extract from the crude ethanolic extract of Toddalia asiatica was chromatographed on silica gel and tested on biological activity. A crystalline was obtained and confirmed as an active constituent in cardiovascular system. The active constituent was identified as isopimpinellin on the basis of chemical method and spectral analysis.

Glycophorin variants and contents of sialic acid and total sulfhydryl groups on erythrocyte membranes of residents in a malaria hyperendemic area

OBJECTIVE

To conduct a screening survey of glycophorin (GP) variants and observe the content changes of sialic acid (SA) and total sulfhydryl (SH) groups on the erythrocyte membranes among residents in a tertian malaria hyperendemic area of Guizhou Province.

METHODS

GP variants were detected in the erythrocyte hemolysates of 173 local residents at two villages of Libo County by SDS-PAGE on 10% to 15% gradients gel and Western immunoblotting. Their SA and total SH group contents were estimated in erythrocyte membranes by spectrophotometric methods. 114 healthy subjects in Changsha and 49 individuals at a neighbouring village of the above area showing low morbidity of malaria served as normal and endemic controls respectively.

RESULTS

Three distinct types of GP variants were found among 19 propositi in this hyperendemic area. The incidence of GP variants was 7.9% (8/101) at Yaolu Village whose population was mainly composed of Yao ethnic group; while that of Buyi ethnic group at Maolan Village was higher (15.3%; 11/72). The erythrocyte membrane contents of SA in residents at both villages exhibited a very significant tendency of decline (P < 0.01), whereas those of total SH groups increased prominently in residents of Yaolu Village only (P < 0.05).

CONCLUSIONS

The frequency of GP variants in this hyperendemic area does not depend upon the severity of malarial prevalence. The evident reduction of SA contents in the residents may be related to the breaking down of the SA residues on membrane GPs by the invasion of Plasmodium vivax.

Male sterility and meiotic drive associated with sex chromosome rearrangements in Drosophila. Role of X-Y pairing

In Drosophila melanogaster, deletions of the pericentromeric X heterochromatin cause X-Y nondisjunction, reduced male fertility and distorted sperm recovery ratios (meiotic drive) in combination with a normal Y chromosome and interact with Y-autosome translocations (T(Y;A)) to cause complete male sterility. The pericentromeric heterochromatin has been shown to contain the male-specific X-Y meiotic pairing sites, which consist mostly of a 240-bp repeated sequence in the intergenic spacers (IGS) of the rDNA repeats. The experiments in this paper address the relationship between X-Y pairing failure and the meiotic drive and sterility effects of Xh deletions. X-linked insertions either of complete rDNA repeats or of rDNA fragments that contain the IGS were found to suppress X-Y nondisjunction and meiotic drive in Xh-/Y males, and to restore fertility to Xh-/T(Y;A) males for eight of nine tested Y-autosome translocations. rDNA fragments devoid of IGS repeats proved incapable of suppressing either meiotic drive or chromosomal sterility. These results indicate that the various spermatogenic disruptions associated with X heterochromatic deletions are all consequences of X-Y pairing failure. We interpret these findings in terms of a novel model in which misalignment of chromosomes triggers a checkpoint that acts by disabling the spermatids that derive from affected spermatocytes.

[A study on apoptotic cell death during chemotherapy of patients with acute leukemia]

OBJECTIVE

To investigate whether apoptosis occurs in vivo in patients with acute leukemia during induction chemotherapy and its significance.

METHODS

Apoptotic effect on peripheral blood of 20 patients with different types of acute leukemia prior to and during routine chemotherapy was studied by cell morphology, DNA electrophoresis and FCM-DNA analysis.

RESULTS

After chemotherapy, with falls in WBC and blast count, no apoptotic cell appeared on smears of peripheral blood, nor did ladder pattern of DNA on electrophoresis and subdiploid peak on FCM.

CONCLUSION

Although anticancer drugs have been shown to induce apoptosis in vitro, circulating apoptotic cells are hardly detected probably due to their rapid clearance from the circulation. It is more difficult to study apoptosis in vivo than in vitro.

Identification of specific mRNAs affected by treatments producing long-term facilitation in Aplysia

Neural correlates of long-term sensitization of defensive withdrawal reflexes in Aplysia occur in sensory neurons in the pleural ganglia and can be mimicked by exposure of these neurons to serotonin (5-HT). Studies using inhibitors indicate that transcription is necessary for production of long-term facilitation by 5-HT. Several mRNAs that change in response to 5-HT have been identified, but the molecular events responsible for long-term facilitation have not yet been fully described. To detect additional changes in mRNAs, we investigated the effects of 5-HT (1.5 hr) on levels of mRNA in pleural-pedal ganglia using in vitro translation. Four mRNAs were affected by 5-HT, three of which were identified as calmodulin (CaM), phosphoglycerate kinase (PGK), and a novel gene product (protein 3). Using RNase protection assays, we found that 5-HT increased all three mRNAs in the pleural sensory neurons. CaM and protein 3 mRNAs were also increased in the sensory neurons by sensitization training. Furthermore, stimulation of peripheral nerves of pleural-pedal ganglia, an in vitro analog of sensitization training, increased the incorporation of labeled amino acids into CaM, PGK, and protein 3. These results indicate that increases in CaM, PGK, and protein 3 are part of the early response of sensory neurons to stimuli that produce long-term facilitation, and that CaM and protein 3 could have a role in the generation of long-term sensitization.

[Effects of exposure to noise in oil-drilling well sites on cochlea in guinea pigs]

OBJECTIVE

To prevent from hearing damage caused by noise in the sites with drilling wells.

METHODS

Intensity and spectrum of the noise produced in the sites with drilling wells were measured and analyzed. Measures, such as sound insulation, vibration damping and changing layouts of the drilling platform, were adopted, and electrocochleography (ECochG) and scanning electron microscopy were used to observe the effects of noise in the sites where drilling wells located on the hearing organs in guinea pigs after exposure.

RESULTS

There was no significant difference in APN1 latency of ECochG before and after exposure to noise. There were significant difference in hearing threshold values between the groups in a room with sound isolation, in moving status and beside the diesel engine, and no significant difference in those between the groups placed one meter horizontally and vertically away from the diesel engine on the drilling platform. Damage to hairy cell under scanning electron microscope was more severe in the guinea pigs placed beside the diesel engine and at the drilling well platform, with inclination and exfoliation of static pili of outer hairy cells, especially in the second and third lines, and part exfoliation of inner hairy cell. Hairy cells of the guinea pigs in a room with sound insulation and in moving status were basically normal. Inclination of hairy cells only could be seen in the third line.

CONCLUSION

Animal experiments indicated that the measures mentioned above are effective and should be applied widely for preventing from hearing damage.

[The analysis of donkey-hide glue, antler glue and tortoise shell glue by means of circular dichroism]

Donkey-hide glue, antler glue, tortoise shell glue and their forgeries were identified by the analysis method of circular dichroism(CD) in this paper. The standard spectra and data were set up. The method is simple, fast and accurate.

[The effect of GM-CSF on endothelin-1 and endothelin converting enzyme gene expression in human airway smooth muscle cells with or without theophylline incubation]

OBJECTIVE

To explore the role of airway smooth muscle cells (ASMC) stimulated by inflammatory factors in the development of asthma and bronchial hyperresponsiveness (BHR) and the possible mechanism of low dose theophylline in the treatment of airway inflammation, the effects of GM-CSF on endothelin-1 and endothelin converting enzyme (ECE) gene expression in human ASMC and theophylline on their expressions were investigated.

METHOD

The cultured human ASMCs were treated with GM-CSF (1,000 micrograms/ml), GM-CSF plus theophylline (125 ng/ml) respectively for 8 hours. Endothelin-1 and ECE gene expresion were measured by RT-PCR.

RESULT

There was no ET-1 gene expression in control group, but strong expression in GM-CSF treated group; theophylline entirely inhibited GM-CSF induced ET-1 gene expression in the ASMC; no significant difference of ECE gene expression was found in three groups.

CONCLUSION

GM-CSF causes a strong ET-1 gene expression but not ECE gene expression in cultured human airway smooth muscle cells; theophyllin inhibites this abnormal expression which may be one of the anti-inflammatory mechanisms of low dose theophylline in the management of chronic airway inflammation.

[Photoluminescence and UV-Vis absorption spectra characteristics of metal complexes of 8-hydroxyquinoline]

8-hydroxyquinoline complexes of Na(I), Ca(II), Mg(II), Zn(II), Cu(II), Mn(II), Al(III), In(III) and La(III) were synthesized. Photoluminescence (PL) and UV-Vis absorption spectra characteristics of these complexes and 8-hydroxyquinoline are reported. Except complexes of Cu and Mn, most of these complexes reveal photoluminescence. With the polarization force of metal cations increasing, the PL peak shows red-shift and two broad absorption peak in UV-Vis (300-400nm) absorption spectra distinctly appears apart.

The biomechanical effect and clinical application of a Ni-Ti shape memory expansion clamp

STUDY DESIGN

The study involves three phases: a clinical study of 30 patients, a biomechanical study to assess the expansion force of a recovering-shape memory expansion clamp, and a biomechanical study using cadaveric specimens to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp.

OBJECTIVE

To evaluate the biomechanical effect and clinical application of the shape memory expansion clamp.

SUMMARY OF BACKGROUND DATA

The major complication of anterior cervical decompression and fusion was graft dislodgement and pseudarthrosis. Improvement of the shape of bone graft and fusion technique could not eliminate the problem completely. The authors designed the shape memory expansion clamp by using the characteristic of Ni-Ti shape memory alloy and first applied it in an anterior cervical operation.

METHODS

The expansion force of recovering of the shape memory expansion clamp was measured in a biomechanical study. Eight fresh human cadaver cervical spine specimens were used to assess the pullout strength of the shape memory expansion clamp as a function of the shape of the clamp. The shape memory expansion clamp had been used to fix rotated circular grafts in 30 cases with cervical spine injuries or cervical spondylosis after anterior decompression.

RESULTS

The expansion force of the shape memory expansion clamp in recovery was 4.65-27.96 N, and the pullout strength was 8.82-20.58 N. Bone fusion was achieved in all 30 cases. Dislocation of bone graft, loosening of clamp, or kyphotic deformity had not occurred.

CONCLUSION

The expansion force and the pullout strength of the partially recovered shape memory expansion clamp were determined biomechanically. The clinical study demonstrated that the shape memory expansion clamp is safe and effective.

Roles of rDNA spacer and transcription unit-sequences in X-Y meiotic chromosome pairing in Drosophila melanogaster males

Meiotic pairing of the X and Y chromosomes in Drosophila melanogaster males is mediated by the rDNA repeats, which are present in two tandem clusters, one in the centric X heterochromatin and the other near the base of the short arm of the Y chromosome. Deletion of the X chromosomal rDNA cluster disrupts X-Y pairing and causes high frequences of X-Y nondisjunction. Pairing can be partly restored by insertions of cloned complete rRNA genes or by rDNA fragments that include the intergenic spacer (IGS) region. A 240 bp repeated sequence in the IGS was shown to be effective in promoting pairing when present at copy numbers above five. This study further defines the rDNA sequences involved in mediating pairing. Germline insertions of a P element construct containing most of the rDNA transcription unit but no promoter or IGS region were obtained. Two single-copy insertions and four two-copy insertions proved unable to stimulate X-Y disjunction when located on an rDNA-deficient X chromosome. In addition, three insertions of a P element construct consisting of the IGS and promoter regions of the rDNA were characterized molecularly. These three insertions had previously been shown to range in pairing ability from very weak to quite strong. Molecular analysis revealed that the three insertions also vary in copy number of the 240 bp IGS repeat and that these structural differences correlate with the differences in pairing ability. These data indicate that 240 bp repeats are considerably more effective than other regions of the rDNA in stimulating chromosome pairing.

[The mutiplication of Sindbis virus and host BHK-21 cell apoptosis]

The process of apoptosis of BHK-21 cells induced by Sindbis virus (SbV) infection is reported here in details. The nuclear DNA cleavage can be first detected at 6 h after SbV infection, followed by the chromatin margination and condensation at 12 h and the DNA ladder can be detected at 24 h after infection. The details of apoptosis body's formation can be revealed by electron microscopy: First, the outer nuclear membrane protrudes where the condensed chromatin accumulates, then the chromatin get into the budding area with the inner nuclear membrane and separate from the nuclear. Progressively, we cloned the gene of SbV nonstructure protein 2 (nsP2) into the eukaryotic expression vector pMAMneo, and it can be expressed transiently. The DNA cleavages, the basic characteristics of apoptosis also can be detected in some cells. Together with the sequence analysis of nsP2 and the other former results, we conclude that the nsP2 may have direct relation with the SbV-induced apoptosis.

[FT-IR study of Ce3+-doped calcium phthalate phosphor]

FT-IR of the CaC8H4O4 : Ce phosphor prepared by the solution reaction method were determined. Bands of their spectra were assigned. Some structure information about these compounds were given.

[Identification of G6PD gene mutations in several nationalities from Yunnan province]

OBJECTIVE

To analyze the G6PD gene mutations in several nationalities from Yunnan province.

METHODS

G6PD gene mutation of 29 samples from G6PD deficient patients were analyzed by using common and mis-matched primering PCR followed by restriction enzyme digestion. The samples were collected from Yunnan province among several nationalities.

RESULTS

In these 29 cases, 20 were of two known mutations, including 19 of 1388 (G-->A) and 1 of 1376 (G-->T) mutation. The 7 cases of national minorities, including 3 of Yi ([symbol: see text]), 2 of Bai ([symbol: see text]), 1 of Dai ([symbol: see text]), and 1 of Naxi ([symbol: see text]), were all 1388 mutations. No report of the G6PD gene 1388 mutation in these ethnic groups was published excepting for Dai.

CONCLUSION

The mutation probably had been prevalent before the emergence of these national minorities. The approximate rate of G6PD gene mutations provided in Yunnan province may, in some respects, help to interpret the molecular evolution.

[Study on the orientation of PET three-dimensional crimp hollow fiber by IR-ATR]

The variations of structure and orientation of poly (ethylene terephthalate) (PET) three-dimensional crimp hollow fiber were investigated by infrared attenuated total reflection (IR-ATR) method. It was found that the carbonyl group of this PET hollow fiber orientates vertically to the fiber surface.

Mutations in the Cacnl1a4 calcium channel gene are associated with seizures, cerebellar degeneration, and ataxia in tottering and leaner mutant mice

Tottering and leaner, two mutations of the mouse tottering locus, have been studied extensively as models for human epilepsy. Here we describe the isolation, mapping, and expression analysis of Cacnl1a4, a gene encoding the alpha subunit of a proposed P-type calcium channel, and also report the physical mapping and expression patterns of the orthologous human gene. DNA sequencing and gene expression data demonstrate that Cacnl1a4 mutations are the primary cause of seizures and ataxia in tottering and leaner mutant mice, and suggest that tottering locus mutations and human diseases, episodic ataxia 2 and familial hemiplegic migraine, represent mutations in mouse and human versions of the same channel-encoding gene.

Role of intracardiac angiotensin II in cardiac dysfunction of rat during septic shock

OBJECTIVE

To observe changes in the content of myocardial angiotensin II and its role in cardiac dysfunction of rat during septic shock.

METHODS

Septic shock model was produced by cecal ligation and puncture (CLP) operation on rats. Experimental rats were given captopril 15 mg.kg-1/d per os for 3 days before CLP operation. Mean blood pressure and left ventricular pressure were recorded. Myocardial angiotensin converting enzyme (ACE) activities were determined by a fluorometric assay and myocardial angiotensin II content was measured by radioimmunoassay. Highly purified membrane of sarcoplasmic reticulum (SR) was prepared from rat hearts. Assays were made of ATP-dependent Ca2+ uptake by cardiac SR and (3H) ryanodine binding to SR.

RESULTS

Myocardial angiotensin II content increased by 51.5% (P < 0.01) at the 18th hour post CLP, meanwhile there was a decrease in left ventricular +/- dp/dtmax value and the impairment in Ca2+ uptake and (3H) ryanodine binding to cardiac SR. Preliminary administration of captopril reduced myocardial ACE activity and angiotensin II content, but increased left ventricular +/- dp/dtmax value. In comparison to shock group, the initial rate and the capacity of SR Ca2+ uptake were increased by 120% (P < 0.01) and 33.9% (P < 0.05), the Bmax value of (3H) ryanodine binding to SR was also elevated, while the Kd value remained unchanged.

CONCLUSIONS

The elevated intracardiac angiotensin II, resulting from the activation of myocardial ACE during sepsis, probably serves as one of the important mediators participating in the pathogenesis of heart failure: the effects of angiotensin II may be associated with the disturbance of Ca2+ transport function of cardiac SR.

Chronic lead exposure alters transthyretin concentration in rat cerebrospinal fluid: the role of the choroid plexus

The choroid plexus, which is responsible for the maintenance of the biochemical milieu of the cerebrospinal fluid (CSF), avidly sequesters Pb. In order to test the hypothesis that chronic Pb exposure may impair choroid plexus function, male weanling Sprague-Dawley rats were exposed to Pb in drinking water at doses of 0, 50, or 250 micrograms Pb/ml (as Pb acetate) for 30, 60, or 90 days. The function of the choroid plexus was assessed as reflected by CSF concentrations of transthyretin (TTR, a major CSF protein manufactured by brain choroid plexus) and CSF essential metal ions (Ca2+, Mg2+, K+, and Na+). TTR concentrations were determined by radioimmunoassay using a monospecific rabbit anti-rat TTR polyclonal antibody, and CSF metal ions analyzed by flame atomic absorption spectrophotometry. Two-way ANOVA of CSF TTR concentrations revealed highly significant dose (p < 0.0001), time (p < 0.0223), and dose-by-time effects (p < 0.0379). Moreover, the percentage of reduction of CSF TTR was directly correlated with Pb concentrations in the choroid plexus (r = 0.703, p < 0.05). Pb exposure significantly increased CSF concentrations of Mg2+, but did not markedly altered CSF concentrations of Ca2+, K+, and Na+. Histopathologic examination under the light microscope did not show distinct alterations of plexus structure in Pb-treated rats. Since TTR is responsible for transport of thyroid hormones to the developing brain, we postulate that the depression of choroid plexus TTR production (and/or secretion) by Pb may impair brain development in young animals by depriving the CNS of thyroid hormones.

[A study of the relevant factors of removal of common bile duct stones with endoscopic mechanical lithotripsy]

Endoscopic mechanical lithotripsy (EML) was attempted in 41 patients with common bile duct stones unable to be removed by endoscopic sphincterotomy. These patients had altogether 89 stones with stone size ranged from 5 to 30 mm (mean transverse diameter 16.6 +/- 6.0 mm and mean longitudinal diameter 20.0 +/- 7.1 mm). 31 patients had 34 stones greater than or equal to 20 mm in transverse diameter. The overall stone removal rate was 97.6%. The rate of complete removal of the stone fragments with EML at one time was 78.6% (11/14) for large, 58.8% (10/17) for middle and 0 (0/5) for small incision of the sphincter. In patients with diameter of the distal common bile duct greater than or equal to 14 mm and less than 9 mm the rate was 83.3% and 30.8% respectively and the difference was of significance (P < 0.05). The rate of complete removal for using basket and balloon catheter was 6/10 and 4/9 separately and that for combined used of these two methods 83.3% (10/12). The rate of spontaneous passage of the stone (within one week) was 1/5. It is concluded that complete removal of the stone fragments was related mainly to the length of the incision, diameter of distal common bile duct and methods of removing stone fragments after the crush with lithotripsy basket; when the stone is large and there is the no space around the stone for lithotripsy basket manipulation, a large amount of diluted contrast material is injected into the bile duct so as to increase the space and facilitate the ensonaring of the stone with lithotripsy basket. Hard stones can not be crushed easily, so they constitute one of the reasons of failure.

A recA-like gene in Drosophila melanogaster that is expressed at high levels in female but not male meiotic tissues

The RecA protein is the central enzyme in prokaryotic recombination. It catalyzes pairing and strand exchange between homologous DNA molecules, and functions in both DNA repair and genetic recombination. The RecA-like proteins Rad51 and Dmc1 of yeast are both required for meiotic recombination and the former is also necessary for repair of double-strand breaks in vegetative cells. Genes encoding Rad51 homologs have been isolated recently from several higher eukaryotes. This paper describes the isolation and molecular characterization of a genomic DNA fragment from Drosophila melanogaster containing the coding sequence for a RecA-like protein. This protein exhibits strong sequence homology with the Rad51 proteins of budding yeast, fission yeast, chickens, mouse and humans, and slightly less (but still strong) homology with yeast Dmc1. Both in situ hybridization and Southern analysis indicate that the Rad51 gene is present only once per genome in Drosophila (at 99D on chromosome arm 3R). However, there are at least three other fragments that cross-hybridize strongly at low stringency. RNA blotting analysis detects a single transcript of about 1.35 kb that is present throughout development at low levels. Transcript levels are induced at least tenfold in ovaries, as measured by RNase protection analysis, suggestive of a role in female meiosis. Transcript levels are significantly lower in testes than in bulk RNA of adult males, however, indicating that Rad51 may be repressed in meiosis of Drosophila males.