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M J Cooper

Publications and source records attributed to M J Cooper.

At least 37 records · Page 2Linked to original sources

Cytochrome c oxidase deficiency associated with the first stop-codon point mutation in human mtDNA.

We have identified the first stop-codon point mutation in mtDNA to be reported in association with human disease. A 36-year-old woman experienced episodes of encephalopathy accompanied by lactic acidemia and had exercise intolerance and proximal myopathy. Histochemical analysis showed that 90% of muscle fibers exhibited decreased or absent cytochrome c oxidase (COX) activity. Biochemical studies confirmed a severe isolated reduction in COX activity. Muscle immunocytochemistry revealed a pattern suggestive of a primary mtDNA defect in the COX-deficient fibers and was consistent with either reduced stability or impaired assembly of the holoenzyme. Sequence analysis of mtDNA identified a novel heteroplasmic G-->A point mutation at position 9952 in the patient's skeletal muscle, which was not detected in her leukocyte mtDNA or in that of 120 healthy controls or 60 additional patients with mitochondrial disease. This point mutation is located in the 3' end of the gene for subunit III of COX and is predicted to result in the loss of the last 13 amino acids of the highly conserved C-terminal region of this subunit. It was not detected in mtDNA extracted from leukocytes, skeletal muscle, or myoblasts of the patient's mother or her two sons, indicating that this mutation is not maternally transmitted. Single-fiber PCR studies provided direct evidence for an association between this point mutation and COX deficiency and indicated that the proportion of mutant mtDNA required to induce COX deficiency is lower than that reported for tRNA-gene point mutations. The findings reported here represent only the second case of isolated COX deficiency to be defined at the molecular genetic level and reveal a new mutational mechanism in mitochondrial disease.

Adult↗

Lack of benefit of very short basic drive train cycle length or repetition of extrastimulus coupling intervals for induction of ventricular tachycardia.

INTRODUCTION: There are considerable variations of uncertain importance in basic drive train cycle lengths and degree of repetition of extrastimuli used in programmed ventricular stimulation protocols in different laboratories. We compare prospectively three different stimulation protocols to examine the influence of a short basic drive train cycle length and repetition of extrastimuli on induction of ventricular tachycardia. METHODS AND RESULTS: Thirty consecutive patients who had documented ventricular tachycardia or fibrillation based on underlying coronary artery disease underwent programmed ventricular stimulation with each of the three study protocols. Protocol A used a basic drive train cycle length of 400 msec with each extrastimulus coupling interval delivered only once. Protocol B used the same basic drive train cycle length, but with each extrastimulus coupling interval repeated three times before decrementing. Protocol C used 300 msec as the cycle length of basic drive trains without repetition of extrastimuli. Sixty-three percent, 67%, and 63% of the study patients had ventricular tachycardia inducible with protocols A, B, and C, respectively (P = NS). Ventricular fibrillation was induced in 23% of the 30 patients in all three protocols. There were no significant differences in the mean cycle lengths of induced ventricular tachycardia, the number of extrastimuli used, and the coupling interval of the last extrastimulus inducing ventricular tachycardia among the three protocols. CONCLUSION: This study showed no clinical benefit for repetition of extrastimuli that have failed to induce a ventricular tachyarrhythmia during programmed ventricular stimulation. A short basic cycle length of 300 msec was not superior to 400 msec for induction of ventricular tachyarrhythmias. We recommend the use of basic cycle length 400 msec with delivery of each extrastimulus interval only once as the initial protocol for programmed ventricular stimulation.

Aged↗

N-terminal domains of human copper-transporting adenosine triphosphatases (the Wilson's and Menkes disease proteins) bind copper selectively in vivo and in vitro with stoichiometry of one copper per metal-binding repeat.

N-terminal domains of the Wilson's and Menkes disease proteins (N-WND and N-MNK) were overexpressed in a soluble form in Escherichia coli as fusions with maltose-binding protein, purified, and their metal-binding properties were characterized. Both N-MNK and N-WND bind copper specifically as indicated by the results of metal-chelate chromatography, direct copper-binding measurements, and chemical modification of Cys residues in the presence of different heavy metals. When E. coli cells are grown in the presence of copper, N-MNK and N-WND bind copper in vivo with stoichiometry of 5-6 nmol of copper/nmol of protein. Copper released from the copper-N-MNK and copper-N-WND complexes reacts with the Cu(I)-selective chelator bicinchoninic acid in the absence of reducing agents. This suggests that in proteins, it is bound in reduced Cu(I) form, in agreement with the spectroscopic properties of the copper-bound domains. Copper bound to the domains in vivo or in vitro specifically protects the N-MNK and N-WND against labeling with the cysteine-directed probe; this indicates that Cys residues in the repetitive motifs GMTCXXCXXXIE are involved in coordination of copper. Direct involvement of the N-terminal domains in the binding of copper suggests their important role in copper-dependent functions of human copper-transporting adenosine triphosphatases (Wilson's and Menkes disease proteins).

Adenosine Triphosphatases↗

Safety-modified episomal vectors for human gene therapy.

The effectiveness of ongoing gene therapy trials may be limited by the expression characteristics of viral and plasmid-based vectors. To enhance levels of heterologous gene expression, we have developed a safety-modified episomal expression vector that replicates extrachromosomally in human cells. This vector system employs a simian virus 40 (SV40) large T antigen mutant (107/402-T) that is deficient in binding to human tumor suppressor gene products, including p53, retinoblastoma, and p107, yet retains replication competence. These SV40-based episomes replicate to thousands of copies by 2-4 days after gene transfer in multiple types of human cell lines, with lower activity in hamster cells, and no detectable activity in dog, rat, and murine cell lines. Importantly, 107/402-T has enhanced replication activity compared with wild-type T antigen; this finding may be due, in part, to the inability of p53 and retinoblastoma to inactivate 107/402-T function. We demonstrate that the level and duration of 107/402-T expression regulates the observed episomal copy number per cell. Compared with standard plasmid constructs, episomes encoding 107/402-T yield approximately 10- to 100-fold enhanced levels of gene expression in unselected populations of transient transfectants. To determine if 107/402-T-based episomes replicate extrachromosomally in vivo, tumor explants in nude mice were directly injected with liposome/DNA complexes. Using a PCR-based assay, we demonstrate that SV40-based episomes replicate in human cells after direct in vivo gene transfer. These data suggest that safety-modified SV40-based episomes will be effective for cancer gene therapy because high level expression of therapeutic genes in transient transfectants should yield enhanced tumor elimination.

Animals↗

Determination of vitamin E in human plasma by high-performance liquid chromatography.

The use of selective protein precipitation to enhance the recovery of vitamin E from plasma, by minimising binding with very-low-density lipoproteins, is reported. The procedure employed treatment of plasma with magnesium chloride and tungstate, followed by methanol protein precipitation. Separation of vitamin E was performed using reversed-phase high-performance liquid chromatography of the methanol extracts with subsequent UV detection of the compound. Using this technique the procedure was observed to be specific for vitamin E and linear over the range 1.0 to 40.0 micrograms/ml. The within-run imprecision (C.V.) at three different supplemented plasma vitamin E concentrations of 5.0, 10.0 and 20.0 micrograms/ml was 4.51, 3.33 and 2.58%, respectively, and the between-run imprecision (C.V.) estimated to be 5.19, 3.69 and 3.67%, respectively. With the same supplemented plasma vitamin E concentrations, the overall accuracy (bias) of the procedure, using an albumin matrix for calibration, was estimated to be 6.0, -5.0 and -3.5%, respectively, and the recovery of vitamin E from six different spiked plasma samples estimated to be 98.2 +/- 2.6%.

Chromatography, High Pressure Liquid↗

High-energy magnetic compton scattering from iron.

The magnetic Compton profile of Fe [111] was measured using circularly polarized synchrotron radiation at incident energies of 84.4, 167.2 and 256.0 keV on the high-energy beamline at the European Synchrotron Radiation Facility. It was found that the momentum resolution of these experiments, which use semiconductor detectors, improves by almost a factor of two over what was previously possible by this technique at photon energies of approximately (1/10)mc(2). It was also observed that all three spectra reduced to the magnetic Compton profile, describing the spin-dependent ground-state momentum density, and that within the experimental error the integrated intensity of the magnetic effect scaled as predicted by the cross section derived in the limit of energies much less than the rest energy of the electron. The magnetic Compton profile of Fe [111], measured using 167.2 keV incident energy and with momentum resolution of 0.42 a.u., was compared with the prediction from a full-potential linearized augmented-plane-wave model profile. The fine structure predicted by theory was confirmed by the experimental profile at this improved resolution.

Journal Article↗

Day-to-day variation of transferrin receptor and ferritin in healthy men and women.

To determine the total day-to-day intraindividual variability of ferritin and transferrin receptor (TfR), we collected venous serum and plasma and capillary serum and plasma samples during 10 nonconsecutive days over a 4-wk period from a group of healthy men (n = 10) and women (n = 11) aged 19-46 y. On the basis of a method previously established in younger and older adults, biological (sigma 2 day) and analytical (sigma 2 rep) variance components were computed and summed to obtain the total day-to-day intraindividual variability (sigma 2 tot). The total day-to-day intraindividual CV (CVtot) was lower for TfR than for ferritin measurements. One to two discrete blood samples are required to accurately determine capillary and venous TfR, whereas capillary and venous ferritin, which have a higher CVtot, require three to six samples. Results from the current study showing the low biological and analytical variability of TfR support the use of this new test for assessing a person's iron status.

Adult↗

Complications of 174 laparoscopic hysterectomies.

The case records of 174 patients who underwent laparoscopic hysterectomy between September, 1992 and April, 1995 were retrospectively reviewed. The mean age of the group was 45.4 (range 17.8-68.5) years, mean weight 70.2 (50-121) kg and mean parity 2.3 (0-4). Laparoscopic hysterectomy (i.e. uterine arteries secured laparoscopically) was performed in 98 patients, laparoscopically assisted vaginal hysterectomy in 70, and laparoscopic subtotal hysterectomy in 6. Bilateral or unilateral oophorectomy were performed in 40 cases. The mean operating time was 131 (45-285) minutes and mean hospitalization 2.6 (1-11) days. Endoscopic stapling devices were used in 135 cases, biopolar diathermy in 117, sutures and ties in 84, and the harmonic scalpel in 29. The overall complication rate was 16%. Seven cases (4%) required conversion to laparotomy. These included 2 inadvertent cystotomies (1 after 2 Caesarean sections), 3 cases of dense uterovesical adhesions following previous surgery and 2 instances of excessive uterine size (> 16 weeks). The mean follow-up period was 2.2 (1-18) months. One patient had a shortened vagina requiring dilatation and another had vault granulations requiring diathermy treatment. Overall 98.3% of patients were satisfied with their surgery.

Adolescent↗

A review of results in a series of 113 laparoscopic colposuspensions.

The case records of 113 women having laparoscopic retropubic colposuspensions (Burch procedure) performed for the treatment of genuine urinary stress incontinence between December, 1992 and April, 1995 were retrospectively reviewed. The mean age of the group was 49.4 (30-80) years, mean weight 72.1 (44.5-114) kg, and mean parity 2.7 (0-8). All patients had preoperative urodynamic study to confirm genuine stress incontinence (GSI). Sixteen patients (14%) had dual pathology (GSI and detrusor instability). A transperitoneal approach was used in 93 operations and extraperitoneal in 20. The mean operating time was 108 (30-320) minutes and mean hospitalization 3.3 (1-10) days. In 13 women the operation was converted to laparotomy; 10 due to adhesions and diminished bladder mobility, 1 for inferior epigastric vessel injury, 1 for an ovarian tumour discovered incidentally at the procedure and 1 for equipment problems. Operative complications included 10 cystotomies (5 repaired laparoscopically), 2 extraperitoneal cases converted to transperitoneal, 1 inferior epigastric vessel injury, 1 vaginal tear, 1 suture through the bladder and 1 case of possible enterotomy oversewn at laparoscopy. The mean follow-up period was 8.4 (1-28) months. All patients were reviewed postoperatively and then contact was attempted either by telephone or in consultation. There was an overall 87% subjective success rate. Two patients felt sutures tear out at 4 and 6 months and were deemed failures; 4 felt their incontinence was improved but had ongoing stress incontinence of urine; 9 had symptoms of detrusor instability and one developed an enterocele 9 months after surgery.

Adult↗

Noninfectious gene transfer and expression systems for cancer gene therapy.

Gene therapy provides a significant opportunity to devise novel strategies for the control or cure of cancer. Success of this modality will ultimately depend on the ability to express a therapeutic gene of interest at high levels, and specific gene delivery to targeted tumor cells will minimize toxicities. Although current gene therapy trials typically use viral-based, infectious vectors to express suitable target genes in human cancer cells, these vectors have significant limitations in their expression characteristics, lack of specificity in targeting tumor cells for gene transfer, and safety concerns regarding induction of secondary malignancies and recombination to form replication-competent virus. These limitations have refocused efforts to develop noninfectious gene transfer technologies for in vivo gene delivery of plasmid-based expression vectors. This article reviews recent developments in non-infectious gene transfer techniques, including liposome and receptor-mediated methods, which can efficiently deliver plasmid vectors into tumor cells in vivo. Additionally, strategies are reviewed for efficiently expressing target genes in tumor cells, including use of tissue-specific promoters, inducible promoters, and replication-control sequences to regulate extrachromosomal amplification of vector DNA in human tumor cells. Optimal coupling of these noninfectious gene transfer and expression technologies have the potential to yield safe and effective gene therapies for patients with cancer.

Gene Transfer Techniques↗

Developmentally imprinted genes as markers for bladder tumor progression.

PURPOSE: Developmentally imprinted genes, such as H19 and insulin-like growth factor-II (IGF-II), play an important role during human embryogenesis and also have been implicated in the pathogenesis of embryonal tumors of childhood. Since H19 is expressed in human fetal bladder, we evaluated 35 bladder carcinomas for H19 expression by in situ hybridization analysis and correlated expression with tumor grade. As a prelude to gene transfer studies to determine if H19 is a bladder tumor oncogene, we also evaluated bladder cell lines for expression of H19, IGF-II, IGF-I and the type I IGF receptor. MATERIALS AND METHODS: H19 expression was evaluated by in situ hybridization analysis in bladder tumor specimens. Northern analysis was used to evaluate the expression of H19, IGF-II, IGF-I and the type I IGF receptor in bladder cell lines. RESULTS: H19 was expressed preferentially in advanced stage tumors: 2 of 12 grade I tumors were H19 positive, whereas 9 of 11 grade II and 7 of 10 grade III tumors expressed H19 (p = 0.004). Additionally, 6 of 6 carcinoma in situ tumors were H19 positive, whereas normal bladder mucosa cells were H19 negative. We found that 3 of 11 cell lines (HT-1376, HT-1197 and 5637) express high levels of H19 mRNA, and each of these cell lines and J82 also express IGF-II. All cell lines examined expressed the type I IGF receptor, whereas there was no detectable IGF-I mRNA. CONCLUSIONS: These data demonstrate that H19 is an oncodevelopmental marker of bladder tumor progression and raise the possibility that H19 may have oncogenic properties in bladder cancer.

Biomarkers, Tumor↗

Training and accreditation in endoscopic surgery.

Increasing concerns following the rapid uptake of endoscopic procedures into routine use and a small number of serious adverse patient outcomes have precipitated calls for guidelines on training and accreditation. A number of international colleges and societies have produced recommendations, although a number of inherent problems remain in the implementation of these. The published literature in the field is quite limited at present, but will undoubtedly expand rapidly.

Certification↗

Bcl-xL is expressed in neuroblastoma cells and modulates chemotherapy-induced apoptosis.

bcl-x is a new member of the bcl-2 gene family and is highly expressed in neural tissues. The present study was designed to determine the expression of the bcl-x gene products in neuroblastoma (NB) and their role in the modulation of chemotherapy-induced apoptosis. Twenty-seven NB cell lines were screened by quantitative immunoprecipitation for Bcl-xL, Bcl-xS, and Bcl-2 expression. None of the cell lines expressed Bcl-xS. Twenty-four of 27 (88%) of the NB cell lines expressed Bcl-xL and 21 of 27 (78%) were positive for Bcl-2. The level of Bcl-xL and Bcl-2 expression was variable among the lines analyzed. Bcl-2 expression was restricted to cells of chromaffin lineage, whereas Bcl-xL was seen in both chromaffin and nonchromaffin lines. To determine whether Bcl-xL could mediate chemotherapy resistance, a NB cell line expressing negligible levels of Bcl-xL was transfected with a bcl-xL expression vector, and unique clones were generated expressing variable levels of Bcl-xL. Cells were treated either with cisplatinum (CP), 4-hydroperoxy-cyclophosphamide (4-HC), or etoposide (VP-16) to induce apoptosis, and cell viability and DNA degradation were determined. Following treatment with CP or 4-HC, Bcl-xL-expressing cells showed significantly increased viability as compared to vector-transfected controls (P < 0.005). Flow cytometric analysis of propidium iodide-stained nuclei following CP or 4-HC treatment revealed significantly increased DNA degradation in controls as compared to Bcl-xL-expressing lines (P < 0.004). DNA analysis by pulsed-field gel electrophoresis revealed high molecular weight (approximately 40 kb) DNA degradation in controls, whereas the DNA in cells expressing Bcl-xL was largely intact. In contrast to CP and 4-HC, results with VP-16 revealed a short-term delay in the onset of apoptosis in Bcl-xL-expressing cells with no long-term survival advantage. The results of these studies indicate Bcl-xL is expressed in NB cells and functions in a manner analogous to Bcl-2 by inhibiting chemotherapy-induced apoptosis.

Animals↗

Fetal echocardiography: retrospective review of clinical experience and an evaluation of indications.

OBJECTIVE: To assess the indications, use, and yield of fetal echocardiography. METHODS: We reviewed our 8-year experience with fetal echocardiography at a large health maintenance organization in northern California to assess the yield of abnormal findings for each indication and the accuracy of prenatal cardiac diagnosis. The study included 915 fetuses undergoing fetal echocardiography between 18-38 weeks' gestation because of accepted indications. All live-born infants had the presence or absence of congenital heart disease (CHD) confirmed postnatally. RESULTS: Family history of CHD led to 34% of all fetal echocardiography studies, with a detection rate of 0.7%. Maternal diabetes mellitus accounted for 28% of all studies, with a detection rate of 1.2%. Exposure of mothers to a potential teratogen led to 48 studies, but no abnormalities were detected. Only 4% of fetal echocardiograms were obtained because of a suspected heart defect noted on a screening obstetric sonogram; this indication had a detection rate of 68% and yielded by far the most cases of severe CHD. Based on the expected occurrence rate of severe CHD in our closed referral system, only about 15% were referred for fetal echocardiography and detected prenatally. CONCLUSION: Basing fetal echocardiography referral on risk factors misses most clinically significant detectable CHD.

Female↗