Chromatin structure analysis by ligation-mediated and terminal transferase-mediated polymerase chain reaction.
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CDC2 Protein Kinase↗
Biomedical subjects
H H Chen
Publications and source records attributed to H H Chen.
Development and specification of muscle sensory neurons.
Although the response properties and synaptic projections of muscle sensory neurons have been studied extensively, relatively little is known about how these sensory neurons develop their unique phenotypes during embryonic life. The explosion of new information on neurotrophins, however, has revealed that neurotrophin 3 (NT3) is critically involved in several aspects of this development, including the initial differentiation, survival, and perhaps even the terminal arborizations of muscle sensory neurons within the spinal cord. The ETS family of transcription factors, recently shown to be expressed in these sensory neurons, may help specify their choice of synaptic targets in the central nervous system.
Afferent Pathways↗
A potential complication of laparoscopy--the surgeon's herniated cervical disk.
Almost all operations that were traditionally performed by open laparotomy operations can be done laparoscopically; however, surgeons may experience several negative health effects. A 37-year-old gynecologic laparoscopist had a herniated intervertebral disk at C5-6 level. Due to a negative trauma history, a possible explanation may be the nonergonomic posture that he held while performing laparoscopic surgery for many hours. To reduce the risk of this complication, we recommend that surgeons' spatial orientation and hand-eye coordination for laparoscopy be improved by sequential phases of training.
Adult↗
Protein kinase C in rat brain is altered by developmental lead exposure.
The absence of learning-related redistribution of hippocampal protein kinase C (PKC) has been correlated with impairment of learning performance induced by developmental lead (Pb) exposure. This study was designed to examine whether the properties of brain PKC are altered by chronic Pb exposure during development. Two-tenth percent Pb acetate was administered to pregnant and lactating dams and then administered to weanlings in drinking water until postnatal day (PN) 56. Effects of Pb on translocation of PKC were studied in brain slices prepared from hippocampus. When the slices were treated with 0.33 microM phorbol-12, 13-dibutyrate (PDBu) for 15 min, a significant increase in PKC activity was observed in the membrane fraction of hippocampal slices from Pb-exposed rats, suggesting that chronic Pb exposure potentiates PDBu-activated PKC translocation. Data obtained from saturation binding assays in the frontal cortices of Pb-exposed rats showed a decrease in the dissociation constant (KD) in both membrane and cytosolic PKC. A decrease in the total binding sites (Bmax) of [3H]PDBu binding was only observed in membrane PKC. Furthermore, developmental Pb exposure decreased PKC-gamma, but not PKC-alpha, -betaII, and -epsilon in the membrane fraction of the hippocampus and the frontal cortex. These results indicate that chronic Pb exposure during development increases phorbol ester binding affinity, enhances phorbol ester-induced translocation of PKC, and down-regulates membrane PKC, mainly PKC-gamma.
Animals↗
Update of the Swedish Two-County Trial of breast cancer screening: histologic grade-specific and age-specific results.
UNLABELLED: The benefit of mammographic screening in reducing mortality from breast cancer is well established. Questions remain with respect to the magnitude of the long-term benefit of modern mammography screening, age specific benefits and the timing of these, and histology specific effects. METHODS: The Swedish Two-County Trial was set up in 1977, with 77,080 women aged 40-74 randomised to invitation to mammographic screening for breast cancer (active study population, ASP) and 55,985 women randomised to no invitation (passive study population, PSP). There is now follow-up for mortality to 31 December 1996, approximately 18 years average follow-up. We investigated the effect of invitation of screening on breast cancer mortality and incidence of advanced tumours by age group (40-49 and 50-74) and histologic type. In addition we estimated progression rates by histologic grade using markov chain models. RESULTS: A significant 29% reduction in breast cancer mortality was observed in association with invitation to screening (relative risk = 0.71, 95% confidence interval 0.60-0.83), maintaining the effect observed at previous stages of follow-up. Age-specific analyses show a smaller and later mortality benefit in women aged 40-49. This is related to the fact that there is a considerable benefit from early detection in terms of mortality from aggressive, poorly differentiated cancers in women aged 50-74, whereas the major effect in women aged 40-49 is on the less aggressive tumours of good or intermediate differentiation. Among women aged 50-74, the incidence of grade III tumours in the ASP is significantly lower than in the PSP, but this is not the case for women aged 40-49. This is related to the greater prevalence and rapidity of progression with respect to histologic grade, as evidenced by the results of markov chain models and the proportions of grade III tumours by time since last screen. CONCLUSIONS: The substantial and significant mortality benefit of invitation to mammographic screening in women aged 40-74 is maintained at 18 years of follow-up. To achieve a substantial mortality benefit at an early stage in the screening program in women aged under 50 years, an interscreening interval of 12-18 months would be required.
Adult↗
Evaluation of screening for nasopharyngeal carcinoma: trial design using Markov chain models.
In this paper, we develop a Markov chain model to estimate parameters pertaining to the natural history of nasopharyngeal carcinoma (NPC). The model is of progression from no disease to Epstein-Barr virus (EBV) infection, preclinical screen-detectable tumour and clinical tumour. We derive tentative estimates of the parameters of the model, based on limited published data, to assess the efficacy of serum screening in conjunction with clinical assessment (indirect mirror examination for NPC), for example the average duration of the preclinical screen-detectable phase is estimated as 3.1 years. We further apply these parameters to a hypothetical screening trial in the Hong Kong population to assess the efficacy of serum screening with clinical assessment by different combinations of screening regime. Results suggest: (1) there is no substantial difference between 3-yearly and 6-yearly serum screening; and (2) within the same serum screening regime annual and 3-yearly clinical assessment can prevent 33% and 28% of deaths from NPC respectively. Prediction of deaths and surrogate end points can be used to estimate the required sample size and duration for designing a randomized trial of screening for NPC. Based on these findings and power projections, we suggest a design for a randomized trial in a high incidence area such as Hong Kong.
Disease Progression↗
Renal actions of synthetic dendroaspis natriuretic peptide.
BACKGROUND: Dendroaspis natriuretic peptide (DNP), recently isolated from the venom of the green Mamba snake Dendroaspis angusticeps, is a 38 amino acid peptide containing a 17 amino acid disulfide ring structure similar to that of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). DNP-like immunoreactivity (DNP-LI) was reported to be present in human plasma and atrial myocardium and to be elevated in human congestive heart failure. Although previously named DNP, it remains unknown if DNP is natriuretic or if is it present in canine plasma, urine, and atrial myocardium. METHOD: Studies were performed in vivo in anesthetized dogs (N = 6) using intravenous infusion of synthetic DNP at 10 and 50 ng/kg/min. Employing a sensitive and specific radioimmunoassay for DNP, the presence of DNP-like peptide was assessed in the canine plasma and urine before, during, and following the administration of exogenous synthetic DNP. Additionally, we performed immunohistochemical studies using the indirect immunoperoxidase method with polyclonal DNP antiserum in normal atrial myocardium (N = 10). Atrial concentrations of DNP-LI were also assessed. RESULTS: We report that DNP is markedly natriuretic and diuretic, which, like ANP and BNP, is associated with the increase in urinary and plasma cGMP. DNP-like peptide is also detected in canine plasma, urine, and atrial myocardium. CONCLUSION: These studies establish that DNP is a potent natriuretic and diuretic peptide with tubular actions linked to cGMP and that DNP may play a physiological role in the regulation of sodium excretion.
Amino Acid Sequence↗
Primary and adjuvant therapy, prognostic factors and survival in 1053 breast cancers diagnosed in a trial of mammography screening.
BACKGROUND: As mammographic screening becomes more widespread, larger numbers of tumours are diagnosed while small and node negative. METHODS: We examined detection mode, tumour size, node status, histological type, therapy and outcome in 1053 breast cancers diagnosed in one county of the Swedish Two-County Trial of mammographic screening for breast cancer. RESULTS: Of patients undergoing total mastectomy with axillary dissection, 65% were found to be node negative. For tumours of size 1-9 mm, 95% were node negative. The major effects on survival were tumour size, node status and histological type. Primary adjuvant therapy had no significant association with survival. CONCLUSIONS: The advent of mammography has substantially enhanced the possibilities for less radical treatment. There is an urgent need for therapeutic trials utilizing mammographic-pathological correlations to ascertain in advance which tumours can and which cannot benefit from more radical therapy.
Adult↗
Effect of a microwave coagulator on implanted liver neoplasms in rats.
An experimental study was conducted to determine the applicability of a microwave (MW) source for coagulation and dissection of metastatic tumour and liver parenchyma. Twenty PVG rats were studied after implantation of MC28 tumour cells into the liver. Eleven days later they underwent sham laparotomy (control) MW coagulation of the tumour deposit, local resection of the tumour deposit with 2 mm clearance or resection of the tumour with MW coagulation of the resection zone. The control animals all died with blood-stained ascites and heavy tumour burden in the liver. After MW coagulation, tumours disappeared in all but one rat. Local resection also led to tumour clearance in 4 of 5 rats. MW coagulation of the resection zone allowed rapid bloodless resection, and no tumour recurrence was observed after 40-89 days. We conclude that MW coagulation is a potentially useful tool for ablation of hepatic metastasis and as an adjunct to hepatic resection.
Animals↗
Postdialysis serum albumin is more rational than predialysis value.
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Body Weight↗
Regional thrombolysis with urokinase for central venous catheter-related thrombosis in patients undergoing high-dose chemotherapy with autologous blood stem cell rescue.
Fifty-one of 300 patients undergoing high-dose chemotherapy with (n = 245) or without (n = 55) autologous stem cell rescue developed central venous catheter-related thrombosis diagnosed by Doppler sonography or contrast venography. Eighteen of these individuals underwent regional thrombolysis defined as the infusion of urokinase into a superficial vein of the ipsilateral upper extremity in a dose not sufficient to produce systemic fibrinolysis by laboratory criteria. Urokinase was administered at a dose of 75,000-150,000 U/hour for 24 to 96 hours and contrast venography was performed to assess response. All individuals had a partial or complete resolution of clinical signs and symptoms. Fifty percent of patients also achieved a partial radiographic response defined as clot lysis with irregular canalization of the vein. Therapeutic doses of heparin for 5 to 7 days and warfarin for at least 3 months were commenced at the conclusion of urokinase therapy. Twelve catheters were salvaged and utilized subsequently until no longer required. Six catheters were removed because of poor catheter function or rethrombosis. The median interval from diagnosis of the thrombus until extraction of the 12 salvaged catheters was 3 months (range 1-8 months). Only a single patient who developed gastrointestinal bleeding required discontinuation of urokinase. Regional thrombolysis is safe, easy to administer, effective in many instances, less costly than the doses of antifibrinolytic agents required to induce systemic fibrinolysis, and should be considered in patients receiving high-dose chemotherapy with autologous stem cell rescue who develop central venous catheter-related thrombosis.
Adolescent↗
Vitamin B6 down-regulates the expression of human GPIIb gene.
Glycoprotein IIb (GPIIb) is the alpha-subunit of the platelet membrane receptor GPIIb/IIIa, which plays a major role in platelet aggregation. Vitamin B6 has been reported to be an antiaggregative agent, although its mechanism is not well known. To understand the molecular mechanism of vitamin B6 on antiaggregation, we analyzed the effects of various forms of vitamin B6 on the expression of human GPIIb promoter using chloramphenicol acetyl transferase (CAT) as the reporter gene. The GPIIb promoter region was amplified by polymerase chain reaction (PCR), cloned into pBLCAT3 to drive the CAT reporter gene and transfected into human erythroleukemia (HEL) cells. Transient expression of the GPIIb promoter was determined after transfected cells were treated with 1 microM pyridoxine (PN), pyridoxal (PL), pyridoxal-5-phosphate (PLP), or 4-deoxypyridoxine (4-dex) for 48 h. Our results show that the GPIIb promoter activity was down-regulated to 54, 35 and 63% in the presence of PN, PL and PLP, respectively, as compared to an untreated control whose promoter activity was 100%. However, no adverse effect on GPIIb promoter was detected by 4-dex, which is an antagonist of vitamin B6. The down-regulation effect of vitamin B6 on GPIIb promoter activity may lead to a reduction of GPIIb protein expression and thus be detrimental to platelet aggregation.
Chloramphenicol O-Acetyltransferase↗
Presence of Dendroaspis natriuretic peptide-like immunoreactivity in human plasma and its increase during human heart failure.
OBJECTIVE: To determine whether Dendroaspis natriuretic peptide (DNP), a novel peptide isolated from the venom of the Dendroaspis angusticeps snake that contains a 17-amino acid disulfide ring structure similar to that in atrial, brain, and C-type natriuretic peptides, is present in normal human plasma and myocardium and whether, like the other natriuretic peptides, DNP-like immunoreactivity (DNP-LI) is activated in human congestive heart failure (CHF). MATERIAL AND METHODS: Circulating DNP-LI was assessed in 19 normal human subjects and 19 patients with CHF (New York Heart Association class III or IV) with a specific and sensitive radioimmunoassay for DNP with no cross-reactivity with the other natriuretic peptides. Immunohistochemical studies that used polyclonal rabbit anti-DNP antiserum were performed on human atrial myocardial tissue obtained from four patients with end-stage CHF who were undergoing cardiac transplantation and from three donor hearts at the time of transplantation. RESULTS: We report that DNP-LI circulates in normal human plasma and is present in the normal atrial myocardium. In addition, DNP-LI is increased in the plasma of patients with CHF. CONCLUSION: This study demonstrates, for the first time, the presence of a DNP-like peptide in normal human plasma and in the atrial myocardium. Additionally, these studies demonstrate increased plasma DNP-LI in human CHF. These results support the possible existence of an additional new natriuretic peptide in humans, which may have a role in the neurohumoral activation that characterizes human CHF.
Animals↗
Anal manometric findings before and after hemorrhoidectomy: a preliminary report.
BACKGROUND: A difference of opinion exists as to whether patients with symptomatic hemorrhoids, patients after hemorrhoidectomy, and patients with no hemorrhoids have different anal physiologies. METHODS: Twenty-four patients with symptomatic hemorrhoids undergoing hemorrhoidectomy were investigated using anorectal manometry. There were 12 male and 12 female patients with a mean age of 42 years (range: 23 to 72 years). The anorectal manometry was performed one day before the operation and 8 to 12 weeks after the operation. Another normal group, comprised of 138 volunteers, was included and matched for age and gender. RESULTS: The anorectal inhibitory reflex was present in all the normal group (NG), symptomatic hemorrhoid (SH), and post-hemorrhoidectomy (PH) patients. No major incontinence was noted clinically. The mean resting pressure (MRP) in the SH group (mean: 84.5 +/- 28.7 cmH2O, range: 26 to 166 cmH2O) was significantly greater than in the NG (mean: 74.4 +/- 14.9 cmH2O, range: 61 to 116 cmH2O) and the PH groups (mean: 63.7 +/- 23.6 cmH2O, range: 20 to 116 cmH2O) (p = 0.032 and 0.005, respectively). After hemorrhoidectomy, the MRP was significantly decreased compared to the normal group (p = 0.018). The other manometric data showed no statistical change in these three groups. CONCLUSION: The results indicate that persons with SH have a higher MRP than normal. Overactivity of the internal sphincter muscle may be a cause rather than a result of symptomatic hemorrhoids. Compared with the SH and normal groups, the MRP was significantly decreased to prevent recurrent symptomatic hemorrhoids in the PH group. Though the MRP was significantly decreased, no major incontinence was noted after hemorrhoidectomy, and this might be due to the increase in rectal compliance and mean squeeze pressure.
Adult↗
Mixed germ cell tumor presenting as intratumoral hemorrhage: report of a case originated from the pineal region.
A 17-year-old male patient was brought to our clinic because of sudden onset of headache, vomiting, followed by transient loss of consciousness during a strenuous exercise. Neurologic examinations revealed that the patient had severe sensorimotor and brain stem dysfunction. Examinations of cranial CT and MR imaging showed a huge heterogeneously enhanced tumor originated from the pineal region with tumoral hemorrhage. The tumor markers were found to be high in AFP but not the beta-HCG and CEA. A clinical diagnosis highly suggestive of germ cell tumor was made. Prior to the planned emergency radiation therapy, he received an external ventricular drainage (EVD) and open biopsy of the tumor. Due to a postoperative complication of cerebellar hemorrhage observed 8 hours later, another maneuver was therefore required to extirpate the pineal tumor and cerebellar hematoma. The histological diagnosis proved to be a mixed germ cell tumor with tumoral hemorrhage. Spontaneous intratumoral hemorrhage in germ cell tumor of the pineal region is rare, probably due to compromised venous circulation within the tumor. The bleeding propensity, which may contribute to the formation of cerebellar hematoma, warrants a special attention when a biopsy procedure is to be performed.
Adolescent↗
Development of a robotic navigation system for neurosurgery.
This paper presents a robotic navigation system for image-guided neurosurgery, which can be applied to the treatment of Parkinson's disease and biopsy of brain tumor. The system integrates a computer for real-time display of brain anatomy, a magnetic tracking device for measuring the positions and orientations of surgical instruments, and a robot manipulator for guiding surgical instruments to the preplanned positions and orientations. The computer display of brain anatomy offers a convenient tool for surgeons to diagnose brain disease and to plan safe surgical paths; while the tracking device assists the robot manipulator to automatically guide surgical instruments to the preplanned direction. The registrations among the tracking device, the image system, and the robot are completed on the base of coordination mappings of external markers. An experiment of using a skull model for simulating a robotic biopsy of brain tumor has been done to verify the performance of the navigation system. The result shows that the system can accomplish a positioning accuracy around 2 mm.
Biopsy↗
Clinicopathologic and cytologic features of a metanephric adenoma of the kidney: a case report.
Metanephric adenoma is a recently described rare and benign renal neoplasm. Our patient, a 37-year-old woman, suffered from flank pain for five months and was found to have a renal mass. Ultrasound, computerized tomography and angiography findings were consistent with a hypovascular renal cyst. Wilms' tumor was the initial misdiagnosis, based on needle biopsy and aspiration cytology. A radical nephrectomy was performed. Histologically, the tumor was well defined and was composed of uniform small cells arranged in a solid, tubular or rosette-like pattern. The prognosis is good for metanephric adenoma. The tumor was first considered a benign counterpart of papillary carcinoma or Wilms' tumor; however, recent cytogenetic evidence suggested that the tumor might be related to papillary adenoma and papillary renal cell carcinoma. The clinical, radiologic, histologic and cytologic features presented here should help to promote the correct preoperative diagnosis and to avoid unnecessary aggressive treatment.
Adenoma↗
Laparoscopic colectomy is superior to laparotomy for reduction of disability in patients with colorectal adenoma.
BACKGROUND: This study was to evaluate disability after laparoscopic colectomy in patients with colorectal adenomas as compared to disability after laparotomy. METHODS: Patients who underwent laparoscopic colectomy for colorectal adenoma were compared to patients who underwent laparotomy for the same problem by the same surgeons during the same time period in Cleveland Clinic Florida. A standard questionnaire was used to assess disability which included the number of days to return to partial activity, full activity, and work. RESULTS: Twenty-nine patients who underwent laparoscopy were compared with 31 patients who underwent laparotomy. There were no significant differences in age (70.4 vs 72.5 years) (p = 0.405) or gender (M:F 13:16 vs 20:11) (p = 0.126) between the laparoscopy and laparotomy groups. The operative time was longer for the laparoscopy group than the laparotomy group: 170 vs 131 minutes (p = 0.014). However, the duration of postoperative ileus, hospitalization, time until return to partial activity, time until return to full activity, and time off of work were significantly shorter in the laparoscopy group than in the laparotomy group: 3.3 vs 5.2 days, 6.2 vs 8.7 days, 2.3 vs 4.2 weeks, 4.4 vs 9.3 weeks, and 3.7 vs 7.3 weeks, respectively (p < 0.041 for all). Although the incidence of postoperative complications was not significantly different (24% for laparoscopy vs 29% for laparotomy, p = 0.325), the incidence of postoperative prolonged ileus was statistically significantly lower in the laparoscopy group (3% vs 26%, p = 0.027). CONCLUSION: Laparoscopic colectomy for patients with colorectal adenoma can reduce postoperative ileus, postoperative hospitalization, and disability in terms of a quicker return to partial activity, full activity, and employment. Laparoscopic colectomy should be considered for all patients who have colorectal adenomas which require resection.
Adenoma↗