[Analysis of the mitochondria-related protein of Schistosoma japonicum and its antigen epitopes]

OBJECTIVE

To sequence the cloned gene Sj338 and to identify the encoded protein and its antigen epitopes.

METHODS

The Sj338 gene fragment obtained from adult S. japonicum cDNA library amplified by PCR method was subcloned into pGEM-T vector for sequencing. The sequence of nucleotides and the characteristics of the encoded protein were analyzed by DNASIS Program and Goldkey DNA and Protein Analytical Program, and then the homology of the amino acid sequence was searched on the BLAST net.

RESULTS

The cloned rSj338 gene was demonstrated to be 487 bp containing one 459 bp ORF, encoding a protein consisted of 153 amino acids with a molecular weight of 17.6 kDa. The amino acid sequence of the recombinant protein rSj338 shared 46% identity with that of the corresponding part of human mitochondrial import receptor and 44% identity with that of the Rattus sp. mitochondrial precursor receptor. The possible antigen epitopes were predicted within the peptide fragments of 26-32 aa, 37-46 aa and 147-151 aa.

CONCLUSION

The protein encoded by rSj338 gene fragment might be the mitochondria-related protein of Schistosoma japonicum.

[Human parasite antigen-specific IFN-gamma response in schistosomitsis japonica endemic area]

OBJECTIVE

To explore the characteristics of human schistosome antigen-specific IFN-gamma response in a population in an area endemic for schistosomiasis japonica.

METHODS

Three neighboring villages were chosen on Nanshan Island of Poyang Lake. 65 egg-negative persons and 64 egg-positive ones were selected randomly from the residents aged 14-41 years according to the egg counts by Kato-Katz thick smear method. IFN-gamma was measured in the whole blood culture supernatant after stimulated by the schistosome soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP). Serum isotype-restricted antibody was detected by ELISA.

RESULTS

IFN-gamma levels induced by both SEA and SWAP were increased significantly after praziquantel treatment. The SEA-specific IFN-gamma level of the uninfected group was much higher than that of the reinfected group. A negative correlation between IFN-gamma level and IgG4 production was found, reflecting that IFN-gamma might be associated with the resistance to schistosome reinfection.

CONCLUSION

The changes in IFN-gamma level might play an important role in association with the resistance to schistosome reinfection.

[Studies on human cytokine responses before and after praziquantel chemotherapy in an endemic area of schistosomiasis japonica]

OBJECTIVE

To observe the cellular immune responses in a population of an endemic area of schistosomiasis japonica and the influence of praziquantel treatment.

METHODS

Blood was taken from 129 residents (64 cases were egg-positive, 65 cases were egg-negitive) of an endemic area of Poyang Lake before and 45 days after praziquantel treatment. Cytokines induced by the schistosome soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP) in the peripheral blood cells including IL-5, IL-10 and IFN-gamma were measured.

RESULTS

Among 129 cases, the cytokine levels were found much higher in egg negative individuals than in egg-positive individuals. The cytokine levels induced by both antigens were increased significantly after praziqantel treatment especially IL-5 and IFN-gamma.

CONCLUSION

The cellular immune responses in the population in schistosomiasis japonica endemic area exhibited a general trend of down-regulation and were elevated significantly after praziquantel treatment.

[Gene cloning and characterization of mitochondria-related protein of Schistosoma japonicum]

OBJECTIVE

To subclone and characterize a cDNA clone coding for Schistosoma japonicum (S.j.) mitochondria-related protein.

METHODS

The open reading frame of the fragment(Sj338/24) obtained from an adult worm cDNA library of S.j. was analysed, at the upstream and downstream of the open reading frame(ORF) the primers A and B were designed, respectively, and the cDNA fragment was used as PCR template. The Sj338 gene fragment obtained was amplified by PCR method and then subcloned into pGEM-T vector for sequencing. The gene sequence was analyzed and the target fragment was restrictedly digested and subcloned into expression vector pGEX-6P-1. The expressed recombinant protein was purified and characterized.

RESULTS

The cloned Sj338 gene was demonstrated to be 487 bp long containing one 459 bp ORF, encoding a protein with a molecular weight of 17 kDa. The nucleotide sequence of the cloned gene Sj338 had higher homology with those genes coding for mitochondrial outer membrane protein of Homo sapiens and Rattus norvegicus. The recombinant construct of pGEX-6P-1/Sj338 could be expressed efficiently and the antigenicity of its product rSj338 has been demonstrated by Western blotting.

CONCLUSION

Sj338 may be the gene coding for S.j. mitochondria-related protein and the recombinant protein may be used as a new vaccine candidate.

Down-regulation of specific antigen-driven cytokine production in a population with endemic Schistosoma japonicum infection

Schistosome antigen-driven cytokine responses and antischistosome antibody levels of residents of a Schistosoma japonicum endemic island in Poyang Lake, Jiangxi Province were studied before and 45 days after treatment with praziquantel. IL-4, IL-5, IL-10 and INF-gamma were all detected in the supernatants of whole-blood cultures after stimulation with schistosome soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP). The percentages of subjects producing detectable amounts of each cytokine assayed were higher in the group who were negative by stool examination at the start of the study than in those who were initially stool positive. After praziquantel treatment the percentages of subjects producing both type I and type II cytokines increased. This suggests that the production of both types of cytokine was down-regulated in the presence of live, egg-laying S. japonicum adult worms but that this was reversible by treatment. In contrast, the antibody studies showed higher levels of SWAP and SEA-specific antibodies (IgE, total IgG, IgG4, IgM) in subjects who were originally stool-positive than in those who were stool-negative. After treatment specific IgE responses were elevated, but total IgG and IgG4 anti-SEA and IgM anti-SWAP antibody levels all fell significantly.

[Histomorphometric analysis in ovariectomized rat with osteoporosis]

OBJECTIVE

To establish the pattern of bone loss of Sprague-Dawley rats after ovariectomy, to investigate and assess the pattern of bone remodeling in ovariectomized rats and the therapeutic action of nilestriol and levenorgestrel.

METHODS

Histomorphometric analysis for bone tissues was performed with the instrument of computerized image analysis.

RESULTS

The trabecular bone volume, mean trabecular thickness, and trabecular bone perimeter were all significantly decreased (P < 0.01) in ovariectomized rats in the 14th week postsurgery compared to the sham operated group. But the osteoblastic index, osteoclastic index, resorptive surface of trabecular, and trabecular surface covered by osteoblast were significantly increased (P < 0.01). There was no significant difference between the treatment group and the sham operated group.

CONCLUSIONS

The pattern of bone loss of rats after ovariectomy has been established successfully. The study provides evidence that the cause of bone loss in the ovariectomized rats is attributable to the increase of bone turnover and negative imbalance in bone remodeling process. The treatment of nilestriol and levenorgestrel may decrease the bone turnover and correct the imbalance to cure the osteoporosis.

Human NKT cells mediate antitumor cytotoxicity directly by recognizing target cell CD1d with bound ligand or indirectly by producing IL-2 to activate NK cells

alpha-Galactosylceramide (alphaGalCer) stimulates NKT cells and has antitumor activity in mice. Murine NKT cells may directly kill tumor cells and induce NK cell cytotoxicity, but the mechanisms are not well defined. Newly developed human CD1d/alphaGalCer tetrameric complexes were used to obtain highly purified human alphaGalCer-reactive NKT cell lines (>99%), and the mechanisms of NKT cell cytotoxicity and activation of NK cells were investigated. Human NKT cells were cytotoxic against CD1d(-) neuroblastoma cells only when they were rendered CD1d(+) by transfection and pulsed with alphaGalCer. Four other CD1d(-) tumor cell lines of diverse origin were resistant to NKT cells, whereas Jurkat and U937 leukemia cell lines, which are constitutively CD1d(+), were killed. Killing of the latter was greatly augmented in the presence of alphaGalCer. Upon human CD1d/alphaGalCer recognition, NKT cells induced potent cytotoxicity of NK cells against CD1d(-) neuroblastoma cell lines that were not killed directly by NKT cells. NK cell activation depended upon NKT cell production of IL-2, and was enhanced by secretion of IFN-gamma. These data demonstrate that cytotoxicity of human NKT cells can be CD1d and ligand dependent, and that TCR-stimulated NKT cells produce IL-2 that is required to induce NK cell cytotoxicity. Thus, NKT cells can mediate potent antitumor activity both directly by targeting CD1d and indirectly by activating NK cells.

[Comprehensive assessment of the ovariectomized rat model of postmenopausal osteoporosis]

Dual-energy X-ray absorptiometry(DEXA), scanning electron microscopy, and bone biomechanical test were used to assess comprehensively bone quantity and quality of ovariectomized rats. In OVX rats, not only bone mineral density (BMD) of lumbar vertebrae in vivo and vitro, but also BMD of femora (except for R3 region) and proximal metaphysis(R1 region) in vitro decreased obviously (P < 0.01), whose bone loss rates of L5 and L6 were the highest and achieved 13%; the trabeculae of OVX rats were few, fine, and discontinued and there were lacunae on the surface; in OVX rats, both compressive strength of vertebral bodies and the mechanical properties of femora decreased; the falling degree of the former was greater; the maximal compressive power of lumbar vertebrae decreased with 33.32%. We conclude that after 4-month post-ovariectomy, the bone quantity and quality of six-month-old rats decreased, especially in the area of abundant cancellous bone such as vertebral bodies, distal femora; the assessment of the efficiency of new drugs to prevent and treat postmenopausal osteoporosis using rat models should include these drugs' effects to the bone mass, the bone structure, and the bone strength.

Surface ozone trends in Hong Kong in 1985-1995

Ozone trends in Hong Kong were assessed from the ozone data recorded at three urban stations and one station in the new development area. Three parameters were selected as the robust trend indicators in the study: monthly mean, monthly averaged daily 1-h maximum, and number of annual hours > 120 microg m(-3). As the ozone data displayed obvious seasonal variation, using deseasonalized monthly average parameters to estimate the ozone trends could smooth out the influence of seasonal fluctuations. The detection of an increase of more than 10% per year in ozone concentration at one station was particularly alarming. Effects of meteorological factors, control programmes of ozone precursors, and long-range transport on the ambient ozone level were examined in the study.

Phase II study with gemcitabine, ifosfamide and cisplatin in advanced non-small cell lung cancer

The aim of the present study was to determine the clinical activity and toxicity of a novel chemotherapy combination regimen of gemcitabine, ifosfamide and cisplatin (GIP), administered every 3 weeks, in patients with inoperable non-small cell lung cancer (NSCLC). From October 1998 to July 1999, 18 previously untreated stages IIIb (4) and IV (14) patients were enrolled into the study. Gemcitabine and ifosfamide (with mesna as uroprotection) was administered on days 1 and 6, at a dose of 1000 and 1500 mg/m2, respectively; and cisplatin was given on day 1 at a dose of 60 mg/m2, every 3 weeks. All 18 patients were evaluable for response and toxicity profiles. One patient achieved a complete response, and II patients achieved a partial response, with an overall response rate of 66.7% (95%, CI, 45-89%). The main toxicity was hematological, a NCI grade 3-4 neutropenia in 16 patients (88.9%) during the treatment course. Febrile neutropenia occurred in three patients (16.6%). Grade 3 anemia occurred in eight patients (44.41%) and grade 3-4 thrombocytopenia occurred in 11 patients (61.1%). Non-hematological toxicity was mild and tolerable. No toxic death occurred. The median survival was 12.7 months and 1 year survival was 58.4%. The GIP combination chemotherapy produced a high response rate in advanced NSCLC; however, there was a relatively high percentage of hematological toxicity that still could be tolerated. A randomized trial comparing GIP to a two-drug combination of gemcitabine and cisplatin is planned.

Lower-dose (13)C-urea breath test to detect Helicobacter pylori infection-comparison between infrared spectrometer and mass spectrometry analysis

BACKGROUND

The expense of the (13)C-urea breath test (UBT) to detect Helicobacter pylori infection is mainly due to the cost of (13)C-urea and the analysis using isotope ratio mass spectrometry (IRMS).

AIM

To test whether a UBT, using a lower dose of urea and lower-priced isotope-selective nondispersive infrared spectrometry (INIS), can preserve diagnostic efficacy in clinical practice.

METHODS

A total of 177 dyspeptic patients received endoscopy for H. pylori culture and histology. All of them received a UBT in which the duplicate baseline, 10 min, and 15 min breath samples after ingestion of 50 mg (13)C-urea were collected to analyse the excess (13)CO(2)/(12)CO(2) ratio (ECR) by IRMS (ABCA, Europa Scientific, UK) and INIS (UBiT-IR200, Photal Otsuka Electronics, Japan), respectively.

RESULTS

Of the 177 patients, 84 were infected and 93 were uninfected with H. pylori. A close correlation of ECR was found between IRMS and INIS (r=0.9829 at 10 min; r=0.9918 at 15 min, P < 0.0001). Analysing the 15-min samples, UBT by both IRMS and INIS achieved the same sensitivity (96. 4%) and specificity (98.9%).

CONCLUSIONS

INIS is as effective as IRMS for UBT, and can use a lower dose of (13)C-urea. This can provide an economic UBT, using the lower-priced INIS and a low dose of (13)C-urea.

Nephrotoxicity of high- and low-osmolar contrast media. The protective role of amlodipine in a rat model

PURPOSE

To evaluate the nephrotoxicity of high- and low-osmolar contrast media (HOCM, LOCM) on kidneys in Sprague-Dawley rats. The protective role of amlodipine was studied.

MATERIAL AND METHODS

Forty rats of both sexes were randomly divided into 5 groups (n=8/group) and glycerine for inducing renal failure was given to all rats except controls.

RESULTS

In diatrizoate-injected rats, blood urea nitrogen (BUN) and serum creatinine (SCr) were increased; levels of phospholipase A2 (PLA2), lipid peroxide (LPO) and calcium were also increased in renal tissues. There was no significant difference between LOCM (iohexol) animals and glycerol controls either in the renal levels of PLA2, LPO and calcium or in the levels of BUN and SCr. The histologic changes were milder in the LOCM animals than in the HOCM animals. In the group pretreated with amlodipine, no increase in the levels of BUN or SCr was discovered and the renal content of PLA2, LPO and calcium were significantly lower than in the HOCM group; the renal injuries induced by diatrizoate were alleviated.

CONCLUSION

The HOCM, diatrizoate, was more toxic to rat kidneys than the LOCM iohexol; PLA2, LPO and calcium load played a role in producing renal function impairment induced by diatrizoate meglumine; amlodipine protected the renal tissue from nephrotoxicity induced by diatrizoate.

Phase II study of tamoxifen, ifosfamide, epirubicin and cisplatin combination chemotherapy in patients with non-small cell lung cancer failing previous chemotherapy

We conducted a phase II study of tamoxifen, ifosfamide, epirubicin, and cisplatin (TIEP) chemotherapy in patients with non-small cell lung cancer (NSCLC) who had failed previous chemotherapy, in order to assess the response and toxicity of TIEP. Between November 1997 and May 1999, 25 patients were treated. Twelve of the 25 patients (48%) had been previously treated with cisplatin-based combination chemotherapy. TIEP doses were tamoxifen 60 mg oral twice daily on days 1-3; ifosfamide 2.4 g/m(2) intravenous infusion (IV) 60 min with mesna on day 2; epirubicin 40 mg/m(2) IV bolus on day 2; and cisplatin 50 mg/m(2) IV 60 min on day 2 every 4 weeks for up to six cycles. Seventy one cycles were given to 25 patients, with a median of three cycles (range one to six cycles). All patients were evaluable for toxicity profile and response rate. As expected, the major toxicity was myelosuppression. Grade 3 or 4 neutropenia occurred in 15 patients (60%) during treatment, as well as in 31% of the total courses. Febrile neutropenia occurred in two patients. No toxic death occurred in this study. Grade 3 thrombocytopenia occurred in five patients with five cycles. Toxicities other than myelosuppression were few and mild in severity. After two cycles of treatment, five of 25 patients (20%) had a partial response (95% confidence interval 4.3-35.7%). Among 12 patients previously treated with cisplatin-based chemotherapy, three patients (25%) achieved a partial response. The median time to disease progression was 4.9 months and median survival was 7.7 months. The response rate and median survival were better than in our previous study of salvage chemotherapy with ifosfamide, 5-FU, and leucovorin; and with ifosfamide, epirubicin, 5-FU, and leucovorin. In conclusion, TIEP appears to be an active combination regimen with an acceptable toxicity profile in Chinese patients with NSCLC who have failed previous chemotherapy.

Combination chemotherapy with tamoxifen, ifosfamide, epirubicin and cisplatin in extensive-disease small-cell lung cancer

BACKGROUND

A study of tamoxifen, ifosfamide, epirubicin and cisplatin (TIEP) chemotherapy was conducted in patients with extensive-disease, small-cell lung cancer (SCLC) to assess response and toxicity.

METHODS

From November, 1997, to February, 1999, 11 patients were treated, including six chemo-naïve patients and five patients previously treated with cisplatin plus etoposide (EP). The treatment regimen included tamoxifen 60 mg twice daily orally on days 1 to 3, ifosfamide 3 g/m2 intravenous (i.v.) infusion for 60 minutes with mesna on day 2, epirubicin 50 mg/m2 i.v. bolus on day 2 and cisplatin 60 mg/m2 i.v. for 60 minutes on day 2, every 4 weeks for up to six cycles.

RESULTS

All patients were evaluated for toxicity and response rate. As expected, the major toxicity was myelosuppression. Grade 3 or 4 leukopenia or neutropenia occurred in all patients during treatment. Two patients (18.2%) experienced fever in association with the neutropenia, one of whom died of sepsis. Grade 3 anemia occurred in two patients (18.2%) during treatment. Toxicities other than neutropenia and anemia were limited. After two cycles of treatment, five of six chemo-naïve patients (83%), and one of five previously treated patients (20%) attained a partial response (overall 54.5%, 95% confidence interval 25%-83.9%). Median survival time was 8.5 and 6 months in chemo-naïve and previously EP-treated patients, respectively. The response rate and median survival time in chemo-naïve patients did not improve compared with a previous study of ifosfamide plus etoposide undertaken 4 years earlier.

CONCLUSIONS

Although TIEP is an active combination regimen with an acceptable toxicity profile in Chinese patients with extensive-disease SCLC, it showed no remarkable benefit compared with other regimens used in chemo-naïve patients. The 20% response rate and median survival of 6 months in EP-treated patients deserve further study.

Integration of computer-assembled digital images and text data as evidence for the oncological record

Digitally created visual images of pertinent patient data have been integrated with text information to formulate a visual evaluation and summary sheet (VESS) using computer processing. The VESS incorporates images of a patient's physical appearance, radiological images, pharmacokinetic graphs, and text information into a 1-page document of the patient's condition. Thus, computer processing of digital images and other information helps to refine patient data presentation, analysis, interpretation, and communication. This form of data management is especially valuable in oncological research, where clinical trials demand rapid, ongoing assessment of results and analysis of large amounts of data. The VESS is an effective mechanism for monitoring both the progress of individual patients and the endpoints of the overall clinical trial.

[Bone mineral density characteristics at the femoral neck and Ward's triangle for Chinese women]

The incidence of hip fracture is not as high in Chinese women compared to women from Western countries, though they usually have low bone mineral density(BMD) and get osteopenia easily. In this study, reference data(white women) supplied by the manufacturer of Hologic was compared with data obtained from healthy women in Changsha, Hunan, P.R.C. One thousand four hundred and eighty-eight Chinese women aged 15 to 95 years were randomly recruited. Measurements of BMD were taken at the hip by the dual energy x-ray absorptiometry(QDR 4,500A, Hologic Inc., USA). The BMD was somewhat lower than reference curves at all ages and all sites. But at the femoral neck and Ward's triangle, Chinese women reached their peak BMD 5 to 10 years later than the reference group, and had a lower BMD rate of decrease for about 35 years after peak BMD was reached. Whether the differences(i.e., longer time to peak BMD and a lower BMD decrease rate at the neck and Ward's triangle after the peak BMD reached) will result in a protection from hip fractures for Chinese women needs to be studied in the future.

Transforming growth factor-beta1 gene and protein expression associated with atherogenesis of cholesterol-fed rabbits

Transforming growth factor-beta1 (TGF-1beta) has been shown to modulate both cell proliferation and the synthesis of extracellular matrix by vascular cells. This study was aimed to establish the temporal correlation between TGF-beta1 expression, the expression of the extracellular matrix protein fibronectin, and plaque development during atherogenesis of hypercholesterolemic rabbits. New Zealand White rabbits were fed with 2% cholesterol-supplemented chow for 1 week, 2 weeks, 3 weeks or 6 weeks. TGF-beta1 mRNA and protein expression was examined in serial sections of aorta by in situ hybridization and immunohistochemistry. Fibronectin expression was examined by immunohistochemistry. In the control and 1-week feeding group, the expression of TGF-beta1 mRNA and protein was not apparent. In 2-week feeding group, intimal thickening was detected in which TGF-beta1 mRNA and protein were not clearly observed, either. The 3-week and 6-week feeding groups exhibited fatty streaks in which TGF-beta1 mRNA and protein expression markedly increased as feeding proceeded. Cell type-specific staining indicated that TGF-beta1 was expressed by macrophages as well as smooth muscle cells of the fatty streaks. Immunostaining of fibronectin detected low expression levels in control, 1-week and 2-week feeding groups with pronounced upregulation in the thickened intima and the proximal media in 3-week and 6-week feeding groups. These results implicate a role for TGF-beta1 in modulating fatty streak formation and the synthesis of extracellular protein fibronectin during plaque development.

Mouse peroxiredoxin V is a thioredoxin peroxidase that inhibits p53-induced apoptosis

We have identified human and mouse peroxiredoxin V (Prx-V) by virtue of the sequence homologies to yeast peroxisomal antioxidant enzyme PMP20. Prx-V represents the fifth of the six currently known subfamilies of mammalian peroxiredoxins. It is a novel organellar enzyme that has orthologs in bacteria. Biochemically, Prx-V is a thioredoxin peroxidase. One important aspect of p53 function in mammalian cells involves induction of apoptosis likely mediated by redox. We show that overexpression of Prx-V prevented the p53-dependent generation of reactive oxygen species. Likewise, Prx-V inhibited p53-induced apoptosis. Thus, Prx-V is critically involved in intracellular redox signaling.

A phase II trial of tamoxifen, ifosfamide, epirubicin, and cisplatin combination chemotherapy for inoperable non-small-cell lung cancer

A phase II trial of tamoxifen, ifosfamide, epirubicin, and cisplatin (TIEP) chemotherapy was conducted in patients with chemonaive inoperable non-small-cell lung cancer (NSCLC) to assess response and toxicity. From October 1997 to August 1998, 19 patients were treated. The treatment schema included tamoxifen 60 mg twice daily by mouth on days 1 to 3, ifosfamide 3 g/m2 intravenous infusion (IV) 60 minutes with mesna on day 2, epirubicin 50 mg/m2 IV bolus on day 2, and cisplatin 60 mg/m2 IV 60 minutes on day 2 every 4 weeks for up to six cycles. All patients were evaluable for response and toxicity. The major toxicity was myelosuppression; grade 3 or 4 leukopenia or neutropenia occurred in 14 of 19 (73.7%) patients during treatment, and 6 patients (31.6%) experienced fever in association with the neutropenia; no toxic deaths occurred. Grade 3 anemia occurred in six patients (31.6%) during the treatment. Grade 3 or 4 nausea/vomiting occurred in only one patient. Toxicities other than neutropenia and anemia were minimal. After two cycles of treatment, 9 of 19 patients attained a partial response (47.4%, 95% confidence interval 24.9%-69.9%) in this study. The median time to disease progression was 6 months and median survival time was 12 months. We conclude that TIEP is an active combination regimen with an acceptable toxicity profile in Chinese patients with inoperable NSCLC.

Assessment of renal function in the early stages of nephrotoxicity induced by iodinated contrast media

To determine whether there are early renal function parameters (RFP) which can be monitored to rapidly detect nephrotoxicity induced by contrast media (CM), we observed RFP in 16 patients with normal renal function before and after administration of CM. Forty-eight hours after diatrizoate meglumine administration, blood urea nitrogen (BUN) and serum creatinine (SCr) increased (p < 0.05). In all patients, acute tubular damage was revealed by early urinary RFP. Increases in levels of serum angiotensin-I-converting enzyme (ACE), beta(2)-microglobulin (beta(2)M) and urinary albumin (Alb) were associated with alterations in glomerular function. The changes in early RFP occurred earlier than those of BUN and SCr. The present study demonstrates that serum ACE, beta(2)M, urinary Alb, gamma-glutamyl-transpeptidase and N-acetyl-beta-D-glucosidase are sensitive parameters for the early assessment of subclinical nephrotoxicity induced by CM.

Optimum length of muscle contraction

OBJECTIVE

The purpose of this study was to develop a mathematical method to determine optimum muscle length and muscle stress based on the measurable physiological and biomechanical data.

DESIGN

The values of optimum muscle length and muscle stress are investigated.

BACKGROUND

Understanding the characteristics of muscle function in vivo is important for assisting the design of the tendon transfer and other rehabilitation procedures. In vivo determination of the physiological and anatomical parameters of muscle contraction is difficult but not impossible. Optimum muscle length and muscle stresses are important parameters for understanding muscle function.

METHODS

A Cybex dynamometer was used to measure isometric elbow flexion torque in eight different joint positions in seven subjects. Then the optimization method was used to determine optimum muscle length and muscle stress of three major elbow flexors, the biceps brachii, the brachialis, and the brachioradialis based on the model and joint torque data.

RESULTS

The calculated muscle stress for each subject was on average 109 N/cm(2), while the optimum muscle length for the biceps brachii, the brachialis, and the brachioradialis was on average 14.05, 6.53, 17.24 cm, respectively. The joint angles corresponding to these optimum muscle lengths are 110 degrees, 100 degrees and 50 degrees of elbow flexion, respectively.

CONCLUSIONS

Optimum muscle length and muscle stress can be properly predicted using an analytical mathematical model along with an experimentally measured joint torque.

RELEVANCE

The estimate of optimum muscle length is important for muscle modeling and tendon transfer surgery by taking advantage of length-tension relationship of individual muscles.

The status of the do-not-resuscitate order in Chinese clinical trial patients in a cancer centre

OBJECTIVE

To report and analyse the pattern of end-of-life decision making for terminal Chinese cancer patients.

DESIGN

Retrospective descriptive study.

SETTING

A cancer clinical trials unit in a large teaching hospital.

PATIENTS

From April 1992 to August 1997, 177 consecutive deaths of cancer clinical trial patients were studied.

MAIN MEASUREMENT

Basic demographic data, patient status at the time of signing a DNR consent, or at the moment of returning home to die are documented, and circumstances surrounding these events evaluated.

RESULTS

DNR orders were written for 64.4% of patients. Patients in pain (odds ratio 0.45, 95% CI 0.22-0.89), especially if requiring opioid analgesia (odds ratio 0.40, 95% CI 0.21-0.77), were factors associated with a higher probability of such an order. Thirty-five patients were taken home to die, a more likely occurrence if the patient was over 75 years (odds ratio 0.12, 95% CI 0.04-0.34), had children (odds ratio 0.14, 95% CI 0.02-0.79), had Taiwanese as a first language (odds ratio 6.74, 95% CI 3.04-14.93), or was unable to intake orally (odds ratio 2.73, 95% CI 1.26-5.92). CPR was performed in 30 patients, none survived to discharge.

CONCLUSIONS

DNR orders are instituted in a large proportion of dying Chinese cancer patients in a cancer centre, however, the order is seldom signed by the patient personally. This study also illustrates that as many as 20% of dying patients are taken home to die, in accordance with local custom.

Mechanical properties of L929 cells measured by atomic force microscopy: effects of anticytoskeletal drugs and membrane crosslinking

To shed light on the architecture of the cytoskeleton, we used the atomic force microscope (AFM) to measure the elasticity, viscoelasticity, and plasticity of L929 cells. The initial elastic response (Young's modulus approximately 4,000 Pa) of the cells to an applied force was followed by a slow compression of the cytoskeleton (tau 1/2 approximately equal to 10 s). When force application was terminated, the cytoskeleton underwent a sudden partial decompression and a subsequent slow, incomplete recovery. The role of the cytoskeletal elements in cell mechanics was accessed in AFM measurements carried out on cells treated with cytochalasin D, nocodazole, or colcemid. Cytochalasin D treatment reduced both elasticity (approximately 45%) and cytoplasmic viscosity (approximately 65%), whereas cells treated with nocodazole or colcemid exhibited a marked increase in elasticity (approximately 100%) and a slight increase in viscosity (approximately 15%). The AFM force measurements also provided evidence that the cell membrane and the cytoskeleton are mechanically coupled. Tightly adherent cells were stiffer than cells that were loosely attached. Moreover, cells crosslinked with either glutaraldehyde, 3, 3'-dithiobis [sulfosuccinimidylpropionate] (DTSSP), or Concanavalin A were more rigid than untreated cells. It is of interest that cells crosslinked with Concanavalin A, but not DTSSP, displayed plastic behaviors that may reflect the induction of cytoskeletal reorganization by Concanavalin A.

An instrumented wheel for kinetic analysis of wheelchair propulsion

An instrumented wheel system for three-dimensional kinetic analysis of upper extremity during wheelchair propulsion has been designed and validated. This system allows the direct measurements of three-dimensional dynamic forces and moments on the handrim during wheelchair propulsion in a laboratory setting as well as in the field. Static loading tests showed a high linearity and little drift (coefficient of determination, r2 > 0.999). Under dynamic loading, the instrumented wheel provided the well-matched measurement forces and moments with the predicted values from the inverse dynamic method using video-based kinematic data (correlation coefficient, p > 0.97). The three-dimensional handrim forces and moments during wheelchair propulsion by a non-disabled subject were demonstrated.