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C Zhou

Publications and source records attributed to C Zhou.

At least 199 records · Page 11Linked to original sources
PubMed1995

Recent advances in biomechanics of brain injury research: a review.

Biomechanics of cerebral trauma attempts to delineate the dynamic response of the cranial vault contents to a direct or indirect impact to the head. Consequently, brain injury mechanisms and associated tolerance to impact can be deduced by establishing a relationship between neurological deficit and mechanical dosage. The resulting information is invaluable to brain injury prevention and diagnosis. This paper presents an overview of our recent research on head injury focusing on establishing brain injury biomechanics by developing a comprehensive and validated mathematical model. To achieve our goal, we developed a comprehensive three-dimensional finite element human head model, finite element porcine head models, and sensors to monitor head kinematics and brain strains by neutral density accelerometers. The information obtained from this research thus far provided a predictive and somewhat validated mathematical model of the head, which clearly shows a correspondence between brain mechanical response and experimentally observed injuries.

Animals↗
PubMed1995

Quantitation of slow drug release from an implantable and degradable gentamicin conjugate by in vivo magnetic resonance imaging.

A biodegradable model hydrogel containing a covalently bound aminoglycoside in which drug release can be monitored by magnetic resonance imaging (MRI) in vivo was developed. The hydrogel consists of the bishydroxysuccinimide ester of polyethylene glycol disuccinate cross-linked albumin, to which gentamicin and Gd-diethylenetriaminepentaacetic acid are covalently attached in stochiometric quantities. MRI allowed us to depict the three-dimensional structure of implanted gels, to accurately calculate their volumes, and thus to calculate the concentration of hydrogel-bound gentamicin. The correlation coefficient for the concentration of released gentamicin and the hydrogel volume was 0.965. Free and hydrogel-released gentamicin conjugates had similar antibiotic efficacies when tested in microbiological agar diffusion assays. In vivo, hydrogel-released gentamicin had a longer half-life in plasma than unaltered gentamicin (5.6 versus 0.7 h), presumably because of residual bound polyethylene glycol residues. Hydrogel implants into rats resulted in a prolonged (7 to 10 days) release of gentamicin and a decreased 24-h mortality in mice infected with a lethal dose of Pseudomonas aeruginosa. The results indicate the feasibility of imaging and quantitating therapeutic drug concentrations in vivo by MRI.

Animals↗
PubMed1995

[Small airway changes in acute interstitial pneumonia and acute exacerbation of chronic interstitial pneumonia].

To study pathologic changes in small airways in acute interstitial pneumonia (AI), changes in the terminal or respiratory bronchioles in one patient with AI and in three patients with acute exacerbations of chronic interstitial pneumonia (grouped together as the AI group) were compared to those in five patients with chronic idiopathic interstitial pneumonia (IIP) without acute exacerbation. Specimens obtained during autopsy were examined by light microscopy. In the AI group, mononuclear cells had infiltrated the lumen in 47 (23.7%) of the 198 bronchioles examined, and granulation tissue was found in 101 (51.0%). In the IIP group, no changes were found in 37 (97.4%) of the 38 bronchioles examined. Therefore, mononuclear cell infiltration and granulation tissue are common in the bronchioles of patients with acute interstitial pneumonia, but not in those of patients with chronic interstitial pneumonia without acute exacerbation.

Acute Disease↗
PubMed1995

[Clinical use of selective reduction in multifetal pregnancies].

Selective reduction under ultrasound guidance was carried out in 12 multifetal pregnancies with over 3 fetuses during 8 to 14 gestational weeks. It was performed transabdominally in 9 women but in other 3, tansvaginal approach was used. Ten women have already delivered 19 viable infants, but the remaining 2 aborted after amniotic rupture during the second trimester. Selective reduction is a safe, feasible method for management of multifetal pregnancies with over 3 fetuses.

Female↗
PubMed1995

[Imaging diagnosis of carcinoma of the ampulla of Vater].

Ten patients with carcinoma of the ampulla of Vater were reviewed with both ultrasonography (US), CT scans (n = 10), and hypotonic double contrast duodenum examination (n = 5). Tumor was shown by US as abrupt obstruction of distal common bile duct (n = 6), a small mass well-delineated within the dilated distal common bile duct (CBD) (n = 4). The second part of duodenum was depicted clearly in CT scan without enhancement, and a small filling defect could be revealed at the inner surface in 5 cases, as well as an abrupt obstruction of distal CBD, local mass was shown in 4 cases. Enhancement of tumor manifested as local mass and/or ductal wall thickening after iv contrast administration was shown in 3 cases. One case with local lymph node enlargement (25 mm) was revealed by US as well as CT. Non-resectability is implicated by the ill-defined contour of tumor mass and/or portal vein, superior mesenteric artery and vein, but resectability cannot be excluded by displacement and distortion of these vessels with clear delineation. Detectability of lymph node smaller than 10 mm and evaluation of T, N staging are limited by imaging examination. Local filling defect and irregularity of mucous membrane of duodenum were revealed in 4 cases by hypotonic double contrast examination.

Adult↗
PubMed1995

Abrupt reduction of c-myc expression by antisense RNA inducing terminal differentiation and apoptosis of a human esophageal cancer cell line.

A human esophageal cancer cell line (EC8712) expressing high-level Myc protein was infected with recombinant retroviral particles (pA-BD9) at a multiplicity of infection (MOI) 1:1. This viral particle contains a neomycin-resistant gene and a 1.53-kb antisense RNA spanning the 2nd exon and its flanking sequences of the human c-myc oncogene. The G418-resistant EC8712 clones showed an 86% inhibition of growth rate and morphological changes characteristic of terminal differentiation and apoptosis. A decrease of about 80% of Myc protein was also observed in these infected cells by ABC-ELISA assay. 12-24 h after the infection of EC8712 cells with pA-BD9 at a high viral particle concentration (MOI = 1:10), the integration of the extrinsic 1.53-kb antisense c-myc fragment into the cancer cell genome was evidenced by the Southern blot analysis. Northern blot analyses showed the expression of this antisense fragment and a decrease of the intrinsic c-myc expression by 74% in comparison with that of the parental EC8712 cells. Heterotransplants of the infected EC8712 cells into the nude mice revealed a substantial decrease in tumorigenicity and morphological changes characteristic of terminal differentiation and apoptosis. Primary monolayer cell cultures of normal epithelia derived from the fetal and adult esophagus mucosa were set as controls. No noticeable increase in c-myc expression was found in these cultures. Infection of these cells with the same recombinant viral particles neither affected the growth rate of the cells nor their normal morphology. Our experiments indicate that the drastic decrease of the over-expressed Myc protein in cancer cells may also be an entrance to one of many pathways leading to the terminal differentiation and programmed cell death.

Animals↗
PubMed1995

A two-year experience with laparoscopic cholecystectomy--a report of 1475 cases from Kunming, China.

Over a 2-year period, from 12 September 1991 to 11 September 1993, laparoscopic cholecystectomy was performed on 1475 patients with benign gallbladder disease in Kunming General Hospital, Yunnan, China. Of these, 28 cases (1.9%) were converted to open surgery. Various complications were documented in 27 instances including extrahepatic bile duct injury in 4 cases (0.3%), postoperative haemorrhage requiring laparotomy in 3 cases (0.2%) and bile leak from cystic duct stump in 1 case (0.07%). There was 1 (0.07%) death in the series. The junction between the gallbladder infundibulum and the cystic duct is an important landmark which laparoscopic surgeons must identify in the course of the procedure. Because the junction remains a comparatively constant landmark, in difficult laparoscopic cholecystectomy, excessive dissection of the bile duct would be unnecessary. During dissection of the hepatic hilus, blund dissection is recommended and the blind use of cautery and haemostasis should be avoided.

Bile Ducts, Extrahepatic↗
PubMed1995

[Small airway obstruction in patients with idiopathic interstitial pneumonia (IIP)--comparison between acute and chronic types].

Small airway obstruction in patients with acute and chronic interstitial pneumonia was studied. Patients with acute interstitial pneumonia (IP, n = 3), and with acute exacerbation of chronic IP (n = 4) were studied as a group, and were compared to patients with chronic idiopathic interstitial pneumonia (IIP, n = 41). Small airway obstruction was defined on a logarithmic %VC-V25/VC plane, because the V25/VC (an index of both small airway obstruction and decreased lung compliance) depended on %VC. Six of seven patients (86%) with acute IP and 8 of 42 patients (19.5%) with chronic IIP had small airway obstruction (p < 0.01). Small airway obstruction was often seen in acute IP, but was not often seen in chronic IIP.

Acute Disease↗
PubMed1995

[Apoptosis of mouse MS-2 fibrosarcoma cells induced by photodynamic therapy with LDL-administered zinc-phthalocyanine].

Photodynamic destruction of MS-2 fibrosarcoma cells in mice induced by LDL-administered Zinc-phthalocyanine and red light irradiation was studied by electron microscopy. The pronounced structural changes such as chromatin condensation, disappearance of nuclear pores, karyopyknosis, karyorrhexis, leakage of chromatin aggregates, autophagocytosis, bleb formation on the cell surface, cytoplasmic vacuolization and cell fragmentation suggest that the tumor cell death was induced by apoptosis. However, its exact mechanism and regulating pathways remain to be further investigated.

Animals↗
PubMed1995

[Long-term study of patients with sequelae of pulmonary tuberculosis after pneumonectomy--obstructive impairment and its causes].

Changes in pulmonary function, chest X-ray films, and CT were retrospectively studied in patients with sequeae of pulmonary tuberculosis 30 years after pneumonectomy (PNX). Over more than 10 years, VC and FEV1% changed at a rate of 23.2 +/- 8.8 ml and 0.683 +/- 0.688% per year, respectively. In the patients studied 30 years after PNX (N = 30), VC was 900 +/- 210 ml, %VC 31.6 +/- 8.1%, and FEV1% was 67.2 +/- 6.8%. About half of these patients had mild airway obstruction. FEV1% was negatively related to the distance from the hilum to the diaphragm on the mid-clavicular line (on the chest films) divided by body height (r = -0.607). Therefore, we think that the airway obstruction may be due to overextension of the bronchi of middle and lower lobes. Emphysema was not found in 18 patients who had no sign of hyperinflation or herniation of the remaining lung to the PNX side on their CT, but it was found in one patient with these signs.

Adult↗
PubMed1995

[Effect of obstetric factors on neonatal hypoxic-ischemic brain injuries].

OBJECTIVE: To determine the effect of high risk obstetric factors on neonatal hypoxic-ischemic brain injuries. The obstetric factors were investigated, including maternal complications during pregnancy and labor, the mode of delivery. METHODS: Intensive B-ultrasound brain monitoring in 211 newborns within the first 48 hours of life was carried out. The abnormalities were followed up by B-ultrasound. We assessed the extent of hypoxic-ischemic brain injuries with two kind of types, mild and severe. The mild type included 1-2 degree intracranial hemorrhage and the local hypoxic-ischemic encephalopathy. The severe type included 3-4 degree intracranial hemorrhage and extensive cerebral edema. RESULTS: Thirty-nine cases (18.5%) were diagnosed intracranial hemorrhage and 22 cases (10.4%) were diagnosed hypoxic-ischemic encephalopathy (HIE) or cerebral edema. The total positive rate was 28.9%. Of the positive cases, 67.2% were mild brain injuries without clinical symptoms. Those cases need no medical treatment and recovered in a natural course. The rates of brain injuries in groups of pregnancy induced hypertension, fetal distress, neonatal asphyxia and premature newborns, were 46.1%, 48.9%, 66.7% and 71.4% respectively. It suggested that high risk obstetric factors were closely related to neonatal brain injuries. 15.9% of positive cases were from normal mothers without any obstetric complications. The brain injuries in those cases were mild. CONCLUSIONS: The study showed that as a non-invasive procedure, B ultrasound brain examination is necessary for newborns with perinatal high risk factors of brain injuries. The study also suggested that perinatal care and systematic fetal monitoring were key-points for reduction of neonatal brain injuries.

Asphyxia Neonatorum↗
PubMed1995

[Long-term study of patients with pulmonary tuberculosis sequelae after bilateral thoracoplasty-airway obstruction and its causes].

Chest roentgenograms and results of pulmonary-function tests in patients with pulmonary tuberculosis sequelae 30 years after bilateral thoracoplasty were studied retrospectively to detect airway obstruction in these patients and to determine its causes. For periods of more than 10 years, vital capacity (VC) changed at a rate of 15.5 +/- 5.0 ml/year, and forced expiratory volume in one second as a percent of VC (FEV1%) changed at a rate of 0.546% +/- 0.380% per year (n = 13). Thirty years after thoracoplasty, the VC was 920 +/- 180 ml (%VC = 28.4% +/- 5.3%), and the FEV1% was 66.2% +/- 13.7% (n = 21). Thus, mild airway obstruction was found in about half of the cases. For each patient, the distance from the hilum to the diaphragm was measured along the mid-clavicular line on the side with fewer ribs resected, and this distance was divided by the patient's height. The results of that computation was found to be significantly and negatively related to FEV1% (r = -0.681, which suggests that longer bronchi in the lower and middle lobes on that side were associated with lower values of FEV1%. These findings are similar to those in patients with pulmonary tuberculous sequelae after total pneumonectomy. Over an average of 26 years, scoliosis, the vertebra showing the most bending, the intrapulmonary lesion, and the position of the diaphragm did not change, but the cardio-thoracic ratio increased.

Adult↗
PubMed1995

[Measurement of Ca2+ concentration and endocochlear potential in experimental endolymphatic hydrops in vivo].

This study was based on observations on 14 normal guinea pigs and 17 guinea pigs in which the left endolymphatic duct and sac had been surgically obliterated to induce endolymphatic hydrops. Three groups of hydropic animals were tested 1, 2 and 3 months after surgery. The Ca2+ concentration and endocochlear potential (EP) were recorded by means of double-barrelled ion selective micro-electrode in the third turn of the cochlea. The results indicated that a decrease in EP and an increase in Ca2+ in hydropic cochlea, a negative correlation was present. In the control ear, the values of Ca2+ and EP were 26.4 +/- 0.33 microns/L (n = 14) and 72.78 mV (n = 14), respectively; in the hydropic ear, the value of Ca/+ was 404.47 +/- 79.74 microns/L (n = 17), while the EP was 55.82 +/- 3.28 mV (n=17). According to Nerstian formula, the slope of electrochemical gradient in the control was 31 mV/decade (n = 14), but in the hydropic ear it increased to 72.5 mV/decade change in Ca2+ (n = 17). The statistical analysis showed significant difference between the control and hydropic ears. The changes were progressive and became more pronounced as the duration of hydrops prolonged. The cause of hearing loss in the Ménière's disease and the relation between the EP and CA2+ concentration had been discussed.

Animals↗
PubMed1994

Inhibition of HIV-1 in human T-lymphocytes by retrovirally transduced anti-tat and rev hammerhead ribozymes.

Gene therapy for AIDS requires the identification of genes which effectively inhibit HIV-1 replication coupled to an efficient vector system for gene delivery and expression. Hammerhead ribozymes are RNA molecules capable of catalytic cleavage of complementary RNA molecules. Ribozymes targeted against two portions of the HIV-1 genome were designed to cleave HIV RNA in the tat gene (TAT) or in a common exon for tat and rev (TR). The ribozymes were cloned into the LN (LTR-neomycin) retroviral vector plasmids and expressed as part of viral LTR-driven transcripts. The vectors were packaged as amphitropic virions and used to transduce human T-lymphocytes. Expression of the vector transcripts containing the ribozyme sequences was readily detected by Northern blot analysis of the transduced T cells. The T-lymphocytes expressing the anti-HIV-1 ribozymes showed resistance to HIV-1 replication. In contrast, cells expressing mutant ribozymes, containing substitutions of a key nucleotide in the catalytic domain which cripples the cleavage activity of the ribozymes, supported replication of HIV-1, demonstrating that the functional ribozymes were cleaving the target RNAs. These studies demonstrate that retrovirally transduced ribozymes included in long, multifunctional transcripts, can inhibit HIV replication in human T-lymphocytes. The ribozyme and expression strategies described here should be useful for the gene therapy of AIDS by conferring resistance to HIV-1 replication on cells derived from transduced hematopoietic stem cells.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Agricultural injuries among a population-based sample of farm operators in Alabama.

A population-based study of the occurrence of agricultural injuries during the previous year was conducted in a simple random sample of 1,000 farm operators in Alabama in 1991. The participation rate was 86.2%. The cumulative 1-year incidence was 9.9% (95% CI = 7.7-12.1), based on the number of injuries, and 7.8% (95% CI = 5.8-9.8), based on the number of farmers injured. Limbs were the body parts most frequently injured: fingers (10.7%), hands or wrists (10.7%), and legs (8.9%). The leading external causes were machinery (28.6%), falls (23.2%), and animals (12.5%). There was a higher injury frequency at the end of the week, with a Saturday peak. Seasonal pattern of injury displayed a bimodal curve, one peak in spring, and a higher peak in early fall in September. The most risky farm types were forestry and dairy. The factors predictive of increased injury risk in multiple logistic regression included younger age, farm ownership, greater percent of working time spent on farming, more alcohol consumed, and prior residual injury. The results provide some indications for formulating agricultural injury control programs and for future research.

Accidents, Occupational↗
PubMed1994

Osmoregulatory alterations in myo-inositol uptake by bovine lens epithelial cells. III. Effects of cycloheximide and colchicine on Na(+)-myo-inositol cotransporter activity under hypertonic conditions, inhibition of a plasma membrane osmotic stress protein.

Cultured bovine lens epithelial cells adapt to hypertonic sodium stress via an increase in Na(+)-myo-inositol cotransporter activity and accumulate myo-inositol. At least 12 hr of hypertonic exposure was necessary to enhance myo-inositol accumulation; and thereafter, uptake activity continued to increase throughout the duration of a 72-hr exposure period. Switching from hypertonic to isotonic medium for 24 hr reversed the otherwise elevated accumulation activity. The protein synthesis inhibitor, cycloheximide, did not affect myo-inositol uptake in isotonic medium but markedly decreased myo-inositol uptake in hypertonic medium. Cells exposed to hypertonic conditions and the microtubule disrupter, colchicine, similarly showed marked impairment of the otherwise enhanced myo-inositol uptake. These studies indicated that hypertonicity-induced elevation of Na(+)-myo-inositol cotransporter activity in cultured bovine lens epithelial cells is not solely attributed to the increased sodium gradient alone, but rather involves increased de novo synthesis of the Na(+)-myo-inositol cotransporter protein(s).

Animals↗
PubMed1994

Clinical observation of treatment of hypertension with calcium.

The effect of oral calcium supplementation (1000 mg/day) on hypertension was studied in 57 borderline and mild-to-moderate hypertensive patients in a randomized, double-blind, placebo-controlled study for 14 weeks. Twenty-five patients from the above groups (11 from the calcium-treated group and 14 from the placebo group) were studied in a crossover fashion for 14 more weeks. The high calcium intake lowered systolic blood pressure by 17 mm Hg (P < .01), and diastolic blood pressure by 11 mm Hg (P < .01). Fifty percent of the calcium-treated patients showed a significant antihypertensive effect and were termed calcium responders. In the crossover study, serum sodium was lower after taking calcium than after placebo intake (P < .05). Pretreatment plasma free calcium content of the calcium-responsive patients was significantly lower (P < .05) than in the calcium nonresponsive patients, and was highly significantly increased (P < .01) after administering calcium. The result showed that oral calcium supplementation can lower blood pressure in a significant fraction of essential hypertensive subjects, and that the free calcium level in plasma may help identify calcium-responsive individuals. While the mechanism by which increased calcium intake lowers blood pressure in hypertension is still undetermined, these data support an underlying relationship between hypertension and calcium and possibly sodium metabolism.

Administration, Oral↗