Propofol inhibits cardiac L-type calcium current in guinea pig ventricular myocytes

BACKGROUND

Propofol may exert negative inotropic and chronotropic actions in the heart. Single-channel studies show that propofol affects the kinetics of opening and closing of cardiac L-type calcium channels (ICa(L)) without altering channel conductance. The aim of this study was to investigate the mechanisms of depressant effects of propofol on cardiac whole-cell ICa(L).

METHODS

Single ventricular myocytes were freshly dissciated from guinea pig hearts using enzymatic isolation. One-suction electrode voltage-clamp technique (whole-cell mode) was used. LCa(L) was separated from other contaminated ionic currents. Propofol was applied in the commercial 10% Intralipid emulsion formula (Zeneca, UK).

RESULTS

In isolated cardiomyocytes, propofol significantly inhibited whole-cell ICa(L) in a concentration-dependent manner (K D = 52.0 microM; Hill coefficient = 1.3). The solvent (Intralipid) did not affect ICa(L). Propofol decreased ICa(L) at all potentials tested along the voltage axis and reduced the slope conductance. The threshold potential for activation and the peak potential of the current-voltage relationship were not changed by propofol. The steady-state activation curves overlapped in the absence and the presence of 56 microM propofol. In contrast, the steady-state inactivation curve was shifted in the hyperpolarizing direction. The time course of the recovery from inactivation was delayed by 56 microM propofol. The blocking action on ICa(L) of propofol shows marked resting block and use-dependent block. Propofol caused more pronounced inhibition at a higher stimulation frequency. The effect of propofol on the inactivation process was even more clear on ICa(L).

CONCLUSIONS

The authors conclude tha propofol, at supratherapeutic concentrations, inhibits cardiac ICa(L). This inhibition is mainly due to a shift of inactivation curve and a reduction in slope conductance.

B and T cells are not required for the viable motheaten phenotype

Hematopoietic cell phosphatase (HCP), encoded by the hcph gene, (also called PTP1C, SHP, SH-PTP1, and PTPN6) is deficient in motheaten (me/me), and the allelic viable motheaten (me(v)/me(v)) mice. Since HCP is expressed in many cell types and protein phosphorylation is a major mechanism of regulating protein function, it is not surprising that the motheaten phenotype is pleiotropic. It is commonly thought that immune system involvement causes this disease. If so, the motheaten disease ought to be alleviated when the recombination activation gene-1 (RAG-1) is disrupted because there will be no V(D)J rearrangement and thus impaired development of B and T cells. We bred homozygous, double-mutant me(v)/me(v) x RAG 1 -/- mice and found that, in fact, inflamed paws, and splenomegaly with elevated myelopoiesis. Thus, except for autoantibodies, the motheaten phenotype does not depend on the presence of B and T cells. This observation cautions the use of motheaten mice as a model of autoimmune disease.

Functional and urodynamic characteristics of Camey II ileal neobladder

The object of this study is to evaluate the functional and urodynamic characteristics of 16 patients who had undergone the Camey II orthotopic bladder replacement after radical cystoprostatectomy. Questionnaires regarding the voiding pattern and urinary continence were answered by 14 patients. Daytime continence was achieved in 13 of 14 patients (93%) at a mean interval of 3 months postoperatively. Eight patients (62%) attained their nighttime continence at an average interval of 10 months. Six of these 8 patients had to void to keep dry at night. Urodynamic studies were completed in 13 patients at an average of 11 months (range 6-23) postoperatively. Patients with nighttime continence had a significantly higher cystometric filling capacity (323 vs. 196 ml, p < 0.001), lower basal pouch pressure (24.5 vs. 35.2 cm water, p = 0.04), lower maximal voiding pressure (62.1 vs. 88.0 cm water, p = 0.01) and higher maximal urethral closure pressure (65.5 vs. 44.0 cm water, p = 0.03). There is no significant difference among the parameters of the age at operation, the amount of residual urine and the functional profile length between these two groups of patients. The antireflux procedure was successful in 11 of 12 patients (92%). We conclude that the Camey II operation could fulfill all the criteria of ideal bladder substitution with adequate volume, low resting pressure, satisfactory continence rate and antireflux characteristic.

Electropharmacological actions of propofol on calcium current in guinea-pig ventricular myocytes

Propofol, a widely-used intravenous anesthetic, causes bradycardia, depression in contractility and hypotension. The cellular mechanisms responsible for these cardiac toxicity remain unclear. In this study, we examined the cellular electropharmacological actions of propofol on calcium current in guinea-pig heart. Single ventricular myocytes were freshly isolated from guinea-pig using modified enzymatic method. Whole-cell voltage-clamp technique was applied with one suction pipette. Transmembrane L-type calcium current (ICa(L)) was separated from other ionic currents by voltage-control, ionic channel blockers and ion substitution methods. Our results show that propofol decreased ICa(L) in a concentration-dependent manner (KD = 54.2 microM). Slope conductance of current-voltage relation was decreased by 56 microM propofol. Propofol did not affect the steady-state activation curve, but shifted the inactivation curve to hyperpolarizing direction. Recovery from inactivation was slowed down by propofol. Marked resting block and use-dependent block were noted. In conclusion, our results indicate that propofol inhibits cardiac L-type calcium current mainly by shifting inactivation curve and retarding the recovery from inactivation.

Optimization of immunohistochemical staining of proliferating cells in paraffin sections of breast carcinoma using antibodies to proliferating cell nuclear antigen and the Ki-67 antigen

Antibodies to proliferating cell nuclear antigen (PCNA) and the MIB-1 antibody to the Ki-67 antigen were titrated to optimize identification of proliferating cells in formalin-fixed paraffin-embedded tissue from a series of 40 human breast carcinomas. Cell culture studies have previously demonstrated that immunostaining for both PCNA and the Ki-67 antigen produces strong granular nuclear staining during S phase. PC10, other anti-PCNA antibodies (PC2, PC5, PC8 and 19F4) and MIB-1 were used at the minimum dilution which allowed a clear distinction between cells with strong and weak staining. With the anti-PCNA antibodies, nickel-cobalt enhancement of the reaction product was found to augment the granular nature of nuclear staining, corresponding more closely to patterns observed in cell culture studies. No enhancement was found to be necessary for MIB-1. The labelling indices of all these antibodies were compared with S phase fraction (SPF) obtained by DNA flow cytometry in the same cases. The PC10 labelling indices which included only strongly stained cells correlated well with SPF, but counting all strongly and weakly stained cells showed a poor correlation. With MIB-1, counting strongly stained as well as all stained cells produced labelling indices which correlated well with SPF, the former tending to be lower and the latter higher. None of the other anti-PCNA antibodies showed any advantage in application over PC10. Thus, PC10 and MIB-1, applied with care, can be correlated with S phase fraction in paraffin processed tissue sections of breast carcinomas.

Characterization of the 3' untranslated region of the mouse homeobox gene HoxB5

The mouse pre-B cell line, 70Z/3, expresses multiple transcripts of the homeobox gene, HoxB5. We show here that this heterogeneity is due, at least in part, to the usage of alternative poly-A addition sites in the 3' untranslated region (UT) of the primary HoxB5 transcript. Furthermore, upon analysis of the subcellular distribution of the different HoxB5 RNA species, we found that the transcripts are present mainly in the nucleus, with two-to-five-fold less RNA present in the cytoplasm. These studies suggest that multiple post-transcriptional regulatory mechanisms are involved in the expression of HoxB5 RNA.

Pathological prognostic factors in the second British Stomach Cancer Group trial of adjuvant therapy in resectable gastric cancer

The second British Stomach Cancer Group trial was a prospective randomised controlled trial of adjuvant radiotherapy or cytotoxic chemotherapy after gastrectomy for adenocarcinoma. It recruited between 1981 and 1986. No survival advantage has been demonstrated for the patients receiving either type of adjuvant therapy compared with those undergoing surgery alone. We report on 436 patients randomised into the trial together with 203 patients, who did not fulfil the trial criteria, referred to the trial. A univariate (log-rank) analysis of pathological factors obtained from the local referring centres showed that tumour size, macroscopic type, number os sites involved, depth of invasion, involvement of resection lines and lymph nodes and histological grade were significant determinants of survival. Histological review by two experienced histopathologists found that the Lauren classification and histological grade, but not the Ming classification, were significant prognostic factors. The degree of lymphocytic and eosinophilic infiltration and presence of dysplasia assessed by one of the pathologists showed a significant correlation with survival. However, inter-observer correlation for these histological parameters and grade was poor. Multivariate analysis identified only depth of invasion, resection line and nodal involvement as significant independent pathological variables influencing survival. This study confirms the need for expert preparation of the resected specimen to obtain the important information on depth of invasion and nodal status and also reveals some variation in histological assessment, particularly grading, in gastric carcinoma.

Reduction of transiently expressed acetylcholinesterase activity in developing thalamocortical projections does not affect the mature pattern of basal forebrain projections to visual cortex

Experiments tested the hypothesis that acetylcholinesterase (AChE) activity, expressed transiently in developing thalamocortical projections, serves to limit the growth of basal forebrain cholinergic projections into thalamocortical recipient zones. Newborn rats were subjected to enucleation, a procedure that eliminates transient AChE activity in developing visual cortex. After 3-8 weeks survival, AChE histochemical techniques revealed no alteration in the pattern of AChE positive basal forebrain axons in visual cortex. These data indicate that transient AChE activity in developing sensory cortex does not limit ingrowth of basal forebrain cholinergic axons.

Neutralization of thoron progeny in gases

This paper reports charge neutralization phenomena of 212Pb particles in nitrogen or oxygen atmospheres with trace amounts of other gases. Newly produced thoron or radon progeny are positively charged, stable molecular clusters that are subsequently neutralized by several mechanisms. The charged clusters have a smaller diffusion coefficient than neutral clusters of the same size due to the interaction of the charge with the surrounding gas molecules. In this study, we have found that the diffusion coefficients of 212Pb in O2, N2, NH3/O2, NH3/N2, and C6H12/N2 (IPs between 15.58 and 9.8 eV) ranged between 0.015 and 0.030 cm2 s-1. In the case of C6H12/O2, NO2/O2, NO/O2, and dimethylamine/O2 (ionization potential between 9.8 and 8.23 eV), the diffusion coefficients have increased to between 0.046 and 0.69 cm2 s-1. These results are consistent with previous results of 218Po, indicating that charged progeny are neutralized by electron transfer from a gas molecule with a lower ionization potential than lead oxide. We estimate the ionization potential of lead oxide to range between 9.8 and 10.2 eV. 212Pb was also neutralized by an electron scavenging mechanism in NO2/nitrogen.

The role of C-reactive protein and erythrocyte sedimentation rate in the diagnosis of infected hydronephrosis and pyonephrosis

Serum C-reactive protein levels and erythrocyte sedimentation rates were prospectively evaluated in 38 patients with dilated pyelocaliceal systems in an attempt to distinguish simple hydronephrosis from infected hydronephrosis and pyonephrosis. The clinical presentations of infected hydronephrosis and pyonephrosis were extremely variable, ranging from no constitutional complaints to urosepsis. Renal sonography detected only 6 of 16 patients with pyonephrosis (specificity 96%, sensitivity 38%, accuracy 72.5%). Using a cutoff value of 3.0 mg./dl. for C-reactive protein and 100 mm. per hour for erythrocyte sedimentation rate, the diagnostic accuracy of detecting infected hydronephrosis and pyonephrosis increased to 97%, with a specificity of 89% and sensitivity of 100%. Based on our experience, we believe that the serum C-reactive protein and erythrocyte sedimentation rate levels can be used as screening tests to distinguish pyonephrosis and infected hydronephrosis from simple, uncomplicated hydronephrosis.

Posttransplant skin cancer: a possible role for p53 gene mutation but not for oncogenic human papillomaviruses

BACKGROUND

Loss of p53 tumor suppressor function is a critical step in the development of diverse malignancies, including skin cancers in nonimmunosuppressed patients where UV-specific p53 gene mutations have been identified. In tumors associated with human papillomavirus (HPV), such as cervical carcinoma, p53 may be inactivated instead by binding to a viral oncoprotein.

OBJECTIVE

Our purpose was to examine the hypothesis that HPV may play an analogous role in the development of posttransplant skin cancer.

METHODS

p53 Immunoreactivity, suggestive of p53 gene mutation, was examined by immunocytochemistry. Oncogenic HPV DNA was detected by polymerase chain reaction.

RESULTS

Comparable p53 immunoreactivity was seen in skin tumors from both transplant and nontransplant patients. HPV DNA was not demonstrated in any tumor specimen.

CONCLUSION

Our data do not implicate oncogenic HPV in posttransplant skin cancer. p53 Gene mutation, rather than HPV-induced p53 degradation, may be more significant in the development of these tumors.

Effect of metabolic alterations on the accumulation of technetium-99m-labeled d,l-HMPAO in slices of rat cerebral cortex

It is widely recognized that the distribution of technetium-99m-labeled d,l-hexamethylpropylene amine oxime (99mTc-HMPAO) in the brain is determined by the regional blood flow. However, other factors may affect this process including the metabolism of the brain tissue. To examine this possibility we studied the effects of metabolic alterations on 99mTc-HMPAO uptake in rat brain cortex slices, with concurrent measurement of oxygen consumption (QO2). 99mTc-HMPAO uptake was determined by incubating slices of rat cerebral cortex at 37 degrees C in Krebs-Ringer phosphate glucose medium containing 99mTc-HMPAO with and without test substances. Differential gradients for 99mTc activity between the tissue and the suspending medium (T/M ratio) were derived from the equation T/M[99mTc] = counts per gram of tissue/counts per milliliter of medium. The QO2 of the brain slices was measured using a biological oxygen monitor equipped with a polarographic oxygen probe. Inhibitors affecting oxidative phosphorylation caused parallel suppression of the T/M ratio and QO2. Agents that uncouple oxidation from phosphorylation increased the QO2 and decreased the T/M ratio. Incubation of slices at 22 degrees C depressed the T/M ratio and QO2. The presence of inhibitors of oxidative phosphorylation in the incubation medium increased the release of 99mTc activity from slices that had been prelabeled with 99mTc-HMPAO. These findings suggest that the altered metabolic status of the brain tissue modulates the kinetics and net accumulation of 99mTc-HMPAO at the cellular level by either depressing uptake, increasing back-diffusion, or both.

Patterns of capillaries in developing cerebral and cerebellar cortices of rats

Patterns of capillaries in cerebral and cerebellar cortices were studied in developing rats. In cerebral cortex, the ventricular zone is well vascularized throughout the developmental period. The cell dense cortical plate is poorly vascularized, with capillary branches appearing in individual layers as they emerge from the cortical plate. In cerebellar cortex, the external granular layer appears devoid of capillary branches. Capillary branching appears first in the Purkinje and granule cell layers and later in the molecular layer. These results indicate: (1) an inside-out pattern of development of capillaries in both cortices, and (2) marked differences in vascularization of the proliferative zones for cerebral and cerebellar cortical neurons.

Intercomparison of activity size distributions of thoron progeny by alpha- and gamma-counting methods

It is difficult to calibrate sampling devices using radon or thoron progeny or particles measuring 1-4 nm; therefore, an interlaboratory comparison is important to verify the performance of graded diffusion batteries for the activity size distributions of the "unattached" progeny. This paper describes the results of an interlaboratory comparison of 220Rn progeny size distributions using graded diffusion batteries by alpha- and gamma-counting methods with different data inversion schemes. Graded diffusion batteries designed at the Inhalation Toxicology Research Institute and at the Environmental Measurement Laboratory were used in the study. Screens and backup filters from the Environmental Measurement Laboratory-graded diffusion batteries were counted simultaneously in alpha counters for total alpha activities, and those of the Inhalation Toxicology Research Institute-graded diffusion batteries were counted in a gamma detector for gamma activities from 212Pb. Because of the different counting methods and data analysis procedures used, this interlaboratory study of 220Rn progeny allows a more rigorous way of testing instrument performance. 212Pb particles generated in well-controlled environments of oxygen, nitrogen, or oxygen with 1 ppm of nitrogen oxide were measured. In general, good agreement in activity size distributions was obtained from these two methods. Some differences observed in individual size spectra were attributable to the data inversion programs used in each laboratory. When the data were analyzed by the same computer program, most differences disappeared.

Percutaneous nephroscopy in the diagnosis of renal pelvic filling defect: a report of two cases

The major differential diagnosis of a radiolucent filling defect within the renal pelvis is among tumor, blood clot and radiolucent stone. In some cases, it is difficult to distinguish tumor from other benign lesions by imaging study. Two patients with renal pelvic filling defect were diagnosed by percutaneous nephroscopy, using the 27 Fr. rigid nephroscope (Olympus, Tokyo, Japan). Both patients got conclusive diagnosis by percutaneous nephroscopy; the morbidity was extremely minimal. The diagnostic percutaneous nephroscopy was a safe and effective procedure with minimal morbidity. For those patients without a conclusive diagnosis in noninvasive procedures, the percutaneous nephroscopy could be an alternative for flexible ureteroscopy, especially for the extremely tortuous ureters.

Update on proliferation-associated antibodies applicable to formalin-fixed paraffin-embedded tissue and their clinical applications

This review provides an update on proliferation-associated antibodies applicable to immunohistochemical techniques in formalin-fixed paraffin-embedded tissue. New insights into proliferating cell nuclear antigen (PCNA) and antibodies to PCNA are presented. The characterization of the protein recognized by the Ki-67 antibody has enabled production of a new range of antibodies (monoclonal and polyclonal) which have immunostaining profiles similar to those of the original antibody. A new proliferation-associated antibody, KiS1, is described. The clinical applications of antibodies to PCNA in human material are summarized, and the limitations of these studies are discussed.

Long-term stone regrowth and recurrence rates after extracorporeal shock wave lithotripsy

We reviewed 1055 patients with symptomatic urinary calculi treated by extracorporeal shock wave lithotripsy (ESWL) monotherapy to determine the long-term stone regrowth and recurrence rates as correlated with the pre-treatment stone burden, site and multiplicity. Long-term follow-up (mean 75.8 months) was available in 94 patients, representing 106 renal units. The recurrence of stone was defined as reappearance of stone on follow-up plain abdominal radiographs. The regrowth of stone was defined as stone regrowing larger than one-third of the original residual size. A stone-free rate of 53% was achieved. The overall stone regrowth and recurrence rates were 26 and 15% respectively. It was concluded that the stone recurrence rate after ESWL was not influenced significantly by the stone size or the multiplicity, but that the regrowth rate was. Stone recurrence and regrowth rates after ESWL were both influenced by the stone location.