Probing the G-protein regulation of GIRK1 and GIRK4, the two subunits of the KACh channel, using functional homomeric mutants

In heart, G-protein-activated channels are complexes of two homologous proteins, GIRK1 and GIRK4. Expression of either protein alone results in barely active or non-active channels, making it difficult to assess the individual contribution of each subunit to the channel complex. The residue Phe137, located within the H5 region of GIRK1, is critical to the synergy between GIRK1 and GIRK4 (Chan, K. W., Sui, J. L., Vivaudou, M., and Logothetis, D. E. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 14193-14198). By modifying this residue or the matching residue of GIRK4, Ser143, we have been able to generate mutant proteins that produced large inwardly rectifying, G-protein-modulated currents when expressed alone in Xenopus oocytes. The enhanced activity of the heterologous expression of each of two active mutants, GIRK1(F137S) and GIRK4(S143T), was not caused by association with an endogenous oocyte channel subunit, and these mutants did not display apparent differences in the ability to localize to the cell surface compared with their wild-type counterparts. When these functional mutant channels were compared individually with wild-type heteromeric channels, they responded with only small differences to a number of maneuvers involving coexpression with muscarinic receptors, G-protein betagamma subunits, wild-type or mutated G-protein alpha subunits, and active protomers of pertussis toxin. These experiments, which confirmed the crucial, though not exclusive, role of Gbetagamma in regulating channel activity, demonstrated that GIRK1(F137S) and GIRK4(S143T), and by extrapolation their wild-type counterparts, interact in a qualitatively similar way with G-protein subunits. These findings suggest that functionally important sites of interaction with G-proteins are likely to be located within the homologous regions of GIRK1 and GIRK4 rather than within the divergent terminal regions. They also raise the question of the functional advantage of a heteromeric over homomeric design for G-protein-gated channels.

High-dose sequential chemotherapy and autologous stem cell reinfusion in advanced pediatric solid tumors

Between January 1993 and December 1996, 21 children with advanced solid tumors were entered in a dose-escalating study of high-dose sequential chemotherapy followed by autologous stem cell transplantation. The diagnoses included neuroblastoma (NB) for 13 patients; Ewing's sarcoma (ES) for six patients and osteosarcoma for two patients. Nine patients received therapy as consolidation for primary metastatic disease, and 12 patients had had previous relapses. Treatment consisted of CY given i.v. at a dose of 7 g/m2 on day 1, followed by G-CSF until myeloid recovery. After 3 weeks of rest, all patients were given thiotepa i.v. on days 22-24. The total dose of thiotepa was 450 mg/m2 in three patients, 600 mg/m2 in six patients, and 750 mg/m2 in 12 patients. Melphalan was given i.v. at a dose of 180 mg/m2 i.v. on day 27 followed by stem cell infusion on day 28. Major toxic reactions included stomatitis, esophagitis, diarrhea and dermatitis. Three patients died of treatment-related complications. Twelve patients have had a relapse. Six patients (five with NB and one with ES) are alive in continuous remission 5-50 months (median 36) after transplantation. The results of this study show that it is feasible to administer high-dose sequential chemotherapy to children with advanced solid tumors.

Clinical predictors of non-diabetic renal disease in patients with non-insulin dependent diabetes mellitus

BACKGROUND

Several studies had suggested that non-diabetic renal disease (NDRD) was common among non-insulin dependent diabetes mellitus (NIDDM) patients with renal involvement.

METHODS

We prospectively studied the prevalence of NDRD among a Chinese NIDDM population. Renal biopsy specimens were evaluated with light-, immunohistological and electron-microscopy. The cohort consisted of 51 patients who had NIDDM and proteinuria > 1 g/24 h.

RESULTS

Patients with both isolated diabetic nephropathy (DN, n = 34) and NDRD (n = 17) had comparable duration of DM, creatinine clearance, serum creatinine, albumin and glycosylated haemoglobin levels, as well as incidences of retinopathy, neuropathy and hypertension. Significantly more patients with NDRD had microscopic haematuria (P = 0.043) or non-nephrotic proteinuria (P = 0.004). IgA nephropathy accounted for 59% of the NDRD identified.

CONCLUSIONS

In this study, microscopic haematuria and non-nephrotic proteinuria predicted the presence of NDRD among NIDDM patients presenting with renal disease.

The accuracy of Papanicolaou smear predictions: cytohistological correlation of 283 cases

The Papanicolaou smear is a highly effective screening test for the detection of cervical neoplastic changes. The success of the test has resulted in unrealistic expectations of the accuracy of the test by both referring medical practitioners and the public. However, as with any pathological test, it has irreducible false negative and positive rates. This report is a comparison between interpretations based on cytological and histological tests and was undertaken to estimate the sensitivity of the Papanicolaou test as practised in Hong Kong. The overall absolute concordance rate for the study was 51.2%. The concordance rates within one diagnostic category were 63.9% and 74.6% for low- and high-grade squamous intraepithelial lesions respectively. The overall sensitivity of the test was 91.7% with a positive predictive value of 93.5%. Ten percent of the error rate was attributed to laboratory error; the remainder was attributed to sampling error and poor smear preparation. Forty-five percent of cases of atypical squamous cells of undetermined significance showed evidence of cervical intraepithelial neoplasia on subsequent biopsy. Follow-up biopsies of low-grade squamous intraepithelial lesions also showed as many lesions from cervical intraepithelial neoplasia grade I as from grades II and III. These findings suggest that colposcopies and biopsies should be performed as soon as possible rather than to repeat the smears in 3 to 6 months. The results of the study may provide guidelines for formulating follow-up recommendations.

Prevalence of six types of human papillomavirus in inverted papilloma and papillary transitional cell carcinoma of the bladder: an evaluation by polymerase chain reaction

AIMS

To study the prevalence of high risk oncogenic human papillomaviruses (HPV) in inverted papilloma and papillary transitional cell carcinoma of the bladder.

METHODS

Ten cases of inverted papilloma and 20 cases of papillary transitional cell carcinoma of the bladder from Chinese patients in Hong Kong were examined for the presence of HPV type 6, 11, 16, 18, 31, and 33 genomes using the polymerase chain reaction and HPV type specific primer probe combinations on paraffin wax embedded biopsy specimens.

RESULTS

Of the 10 cases of inverted papilloma, cases 1 and 6 showed the presence of HPV types 16 and 18, respectively. Six of the 20 papillary transitional cell carcinomas were positive for HPV type 18. The other HPV types were not detected.

CONCLUSIONS

HPV type 18 was found in 60% and 30% of cases of inverted papilloma and papillary transitional cell carcinoma of the bladder, respectively. These tumours were rarely associated with HPV types 6, 11, 16, 31, and 33. The role of HPV type 18 in oncogenesis of inverted papilloma and transitional cell carcinoma of the bladder requires further studies.

Secular trend and age-period-cohort analysis of prostate cancer mortality in Taiwan

PURPOSE

We evaluated the secular mortality trend of prostate cancer in Taiwan from 1964 through 1994.

MATERIALS AND METHODS

Analyses were based on vital statistics. Relative risks associated with each of the age, period and cohort effects on secular mortality were estimated from a log-linear Poisson model.

RESULTS

Age adjusted mortality rates increased more than 2-fold during the last 30 years in Taiwan. Age-period-cohort analysis showed that the age effect was the strongest.

CONCLUSIONS

Factors related to aging are the main reason for the increase in prostate cancer mortality in Taiwan during the least 3 decades.

Dapsone for Pneumocystis carinii prophylaxis in children undergoing bone marrow transplantation

Children who undergo bone marrow transplantation (BMT) are at risk for Pneumocystis carinii pneumonia (PCP). Prophylaxis using trimethoprim/sulfamethoxazole (TMP/SMX) is highly effective but the incidence of adverse drug reactions is significant. We retrospectively reviewed 33 pediatric BMT (25 allogeneic and eight autologous) in whom dapsone was used for PCP prophylaxis because patients were unable to receive TMP/SMX. Dapsone was administered at 50 mg/m2 p.o. once a week from engraftment to 180 days post-autologous BMT, and to 1 year or throughout the duration of immunosuppressive treatment post-allogeneic BMT. With a total of 7268 patient days of dapsone prophylaxis and a median follow-up of 353 days post-BMT, no proven PCP was diagnosed. Sixteen cases of chest radiograph abnormalities were noted in this patient population but none was attributed to PCP. Dapsone was well tolerated by all children with no serious adverse effects; however, one patient developed Toxoplasma gondii encephalitis during dapsone prophylaxis. Dapsone warrants further evaluation as an alternative for PCP prophylaxis in pediatric BMT patients intolerant of TMP/SMX. Additional prophylaxis should be considered for patients at high risk for T. gondii encephalitis.

The effect of in vivo ethanol consumption on cyclic AMP and delta-opioid receptors in mouse striatum

In this study the effect of in vivo ethanol consumption on cyclic AMP (cAMP) and [D-Ala2,D-Leu5]enkephalin (DADLE) inhibition of forskolin-stimulated cAMP production was examined in mouse striatum. Effects of ethanol on striatal delta-opioid receptor (DOR) density and mRNA were also examined. Mice had unlimited access to 7% (v/v) ethanol alone or water for 1 or 7 days and were then sacrificed and striatum removed for analysis. There was no difference in basal cAMP formation between water and ethanol-treated mouse striatum following 7 day treatment, and a small, but statistically significant increase in basal cAMP in the ethanol group following 1 day treatment. Both 1 day and 7 day ethanol treatment did not significantly alter the percentage increase in cAMP following treatment with 10 microM forskolin. There was a significant effect of ethanol treatment on the maximum inhibitory effect of DADLE on forskolin-stimulated cAMP formation following both 1 and 7 day ethanol treatment. The DADLE IC50 was unaffected by ethanol treatment. Saturation binding studies ([3H]Deltorphin II) indicated no effect of ethanol on Bmax or Kd in striatum. Similarly, no difference between water and ethanol-treated was observed for DOR mRNA in striatum. These data indicate that ethanol consumption can alter opioid regulation of cAMP formation. However, this effect is not related to changes in any delta-opioid receptor parameters that were examined.

Improved Papanicolaou smear reporting through the use of automated data entry

The implementation of an automated data entry and report generation system using an optical scanner and commercially available image processing program is described. This method could be easily adapted for use in other fields of medical research where the compilation of a large amount of repetitive data is involved, such as the filling in of questionnaires. Using an optical scanner for data entry improves the efficiency of report generation, thereby improving the turnaround time of reports. Reports are standardised and more easily understood by referring doctors. Data is also standardised and validated and is more amenable for quality assurance analysis, in the reminder service for patients, and gives a performance analysis of smear takers.

Immunostaining of estrogen receptor, progesterone receptor, MIB1 antigen, and c-erbB-2 oncoprotein in cytologic specimens: a simplified method with formalin fixation

An effective but simple fixation protocol for the immunocytochemical staining of cytologic smears for estrogen and progesterone receptors, the Ki-67 antigen (using MIB1 antibody), and c-erbB-2 protein is described. One hundred twenty-seven smears from a variety of malignant and benign breast lesions showed good preservation of antigenicity when subjected to the following fixation protocol: Freshly made smears were air-dried for 20 min to 14 h at 22 degrees C before immersing in 10% buffered formalin for 2-14 h. Immunostaining followed microwave-stimulated epitope retrieval. There was strong concordance of staining with corresponding tissue sections in 15 cases of malignant tumors (ER: r = 0.7381; PR: r = 0.6684; MIB1: r = 0.7234). Immunostaining staining, when delayed for 5-10 days in about half the smears, showed no noticeable difference in reactivity, attesting to effective storage of the formalin-fixed smears at room temperature.

A retrospective drug utilization evaluation of antihyperlipidaemic agents in a medical centre in Taiwan

OBJECTIVE

The purpose of this study was to retrospectively evaluate the prescribing of antihyperlipidaemic agents in an 800-bed medical centre in southern Taiwan.

METHODS

A retrospective study based on reviewing medical records was conducted using a computerized database. We randomly selected 344 patients (age range 5-85 years) who received an antihyperlipidaemic agent between 1 April 1994 and 30 September 1994 and reviewed their medical records. All the related data from the date when the antihyperlipidaemic agent was first prescribed to 31 December 1994 was assessed. Usage guidelines for antihyperlipidaemic agents were defined by referring to the literature and specialist opinion.

RESULTS

Two hundred and twenty-two patients (64.5%) were treated with antihyperlipidaemic agents in accordance with the usage guidelines. In addition, most of the treatments complied with the regulations laid down by related health insurance programmes. The other 122 cases (35.5%) failed to meet any of the indications of the usage guidelines. Only 102 patients (29.7%) had their baseline lipid profiles examined and 117 patients (34%) had their baseline liver function tested. Over all, very few cases had lipid profiles and liver function tests every 3 months while taking antihyperlipidaemic agents. Patients who had been prescribed antihyperlipidaemic agents for more than 1 year were evaluated to assess the effectiveness of their pharmacological therapy. The prescribed doses were found to be lower than recommended in the general literature except for patients who received lovastatin and pravastatin.

CONCLUSIONS

There are many treatment guidelines for hypercholesterolaemia in north America and Europe. This study revealed that a large proportion of antihyperlipidaemic agents used in our patient population did not comply with these general recommendations. Although the reasons for not complying with usage guidelines need to be further investigated, our study findings may well serve as the basis for further quality management and pharmacoeconomic analysis.

Arteriovenous shunts in patients with hepatic tumors

The study aimed to investigate the influence of tumor type, tumor size, tumor vascularity and treatment on arteriovenous shunts between the liver and lungs in patients with hepatic cancer.

METHODS

Our previous assessment of the degrees of lung shunting using intra-arterial 99mTc-macroaggregated albumin in 125 patients with hepatocellular carcinoma (HCC) was extended to include 377 patients with HCC and 25 patients with colorectal liver metastases. Patients were given 111 MBq (3 mCi) of 99mTc-macroaggregated albumin during hepatic angiography. The lungs and the liver were localized as regions of interest on the digitized gamma scintigraphic image. The total counts taken over the lungs divided by the total counts taken over both the lungs and the liver gave the percentage of lung shunting. Tumor size was measured by computerized tomography or ultrasound scan. Tumor vascularity was assessed based on the degree of neovascularization. Linear regression and Wilcoxon rank test were used for statistical analysis.

RESULTS

Patients with HCC had a higher median (7.6%) and a wider range (< 1-75.4%) of percentages of lung shunting when compared with those with colorectal liver metastases (median, 4.7%; range, < 1-23.9%). The lung shunting correlated with the tumor size in the 377 patients with HCC (r = 0.359; p < 0.0001). Excluding one outlier, we found a similar correlation in 24 patients with colorectal metastases (r = 0.686; p < 0.0001). In HCC, the mean lung shunting increased with increasing tumor size, up to 15 cm, and then remained almost unchanged, up to a size of > 20 cm. The mean lung shunting also increased with increasing vascularity grades, as assessed by hepatic angiography. The difference between any two vascularity grades was statistically significant (p = 0.0001-0.0148). Similar analysis by subgroups in colorectal liver metastases was impossible because of the small number of patients. Lung shunting decreased in HCC patients after the tumors were treated, but it might increase or decrease when the disease recurs.

CONCLUSION

The lung shunting was influenced by the type, size and vascularity of the hepatic tumor. The change in lung shunting with the status of the tumor after treatment further suggests a neoplastic nature of the blood vessels involved in the arteriovenous shunt.

Tumour-to-normal uptake ratio of 90Y microspheres in hepatic cancer assessed with 99Tcm macroaggregated albumin

The selective delivery of a high dose of radiation to malignant hepatic tumours by infusion of non-biodegradable yttrium-90 (90Y) microspheres via the hepatic artery while sparing the non-tumorous liver parenchyma depends on the tumour-to-normal uptake ratio (T/N) of the therapeutic radiopharmaceutical. Using intrahepatic arterial technetium-99m macroaggregated albumin (99Tcm-MAA), the effect of tumour type, tumour vascularity assessed by hepatic angiography (HAG), tumour size and the degree of extrahepatic shunting on the T/N was investigated in 377 patients with hepatocellular carcinoma (HCC) and 25 patients with colorectal liver metastases. HCC was shown to have a wider range of T/N (0.2-26.5) compared with liver metastases (2.3-7.2). HCC with vascularity grade 1 on HAG had significantly lower T/N but there was no significant difference in HCC with higher vascularity grades. This confirmed that vascularity on HAG does not predict T/N. Overall there was no correlation between T/N and tumour size. Large tumours (> 20 cm) had a significantly lower T/N, probably due to necrosis in the tumour centres. A decrease in mean T/N with increasing percentages of lung shunting was observed in HCC. Determination of T/N by simulation with 99Tcm-MAA is recommended before internal radiation therapy with 90Y microspheres.

Effectiveness of low-dose ASA in prevention of secondary ischemic stroke, the ASA Study Group in Taiwan

This randomized double-blind controlled study was carried out to investigate the effect of 100 mg acetylsalicylic acid (ASA) per day on the secondary prevention of ischemic stroke. Patients who suffered a first ischemic stroke from 13 participating hospitals were enrolled. They were independent or only partially dependent in activities of daily living and all had received brain CT for diagnosis. Eligible patients were randomly allocated to the 100 mg ASA or the nicametate citrate (a vasodilator) groups, and trial medications were started within three to six weeks after the onset of stroke. The primary end point was cerebral reinfarction, and intracranial hemorrhage was classified as an adverse event. Four hundred and sixty-six patients participated in this study; and 222 cases (136 males and 86 females) were allocated to the ASA group while 244 cases (150 males and 94 females) were assigned to the nicametate group. No significant difference in baseline characteristics between the two groups was observed. Cerebral reinfarction developed 6.3% (14/222) in the ASA group and 11.9% (29/244) in the nicametate group. According to the Cox's proportional hazards model, the estimated risk ratio (ASA group vs. nicametate group) was 0.538, with a 95% confidence interval of 0.284-1.019. The result was of borderline statistical significance. The risk for cerebral reinfarction was reduced by almost 50% among those who took 100 mg ASA versus those who took nicametate.

Systemic inflammatory response syndrome in intravascular lymphomatosis

Intravascular lymphomatosis (IVL) is characterized by an intravascular proliferation of atypical mononuclear cells of haematopoietic origin occluding small blood vessels including venules, capillaries and small arteries, and can affect virtually any organ in the body. Clinically, the most common manifestations are involvement of the skin and central nervous system, although various organ involvement has been described. We report a patient who presented with fever and rash, and succumbed with acute neurological symptoms and systemic inflammatory response syndrome (SIRS) with no evidence of infection. The postmortem revealed disseminated involvement of virtually every organ with IVL, the malignant cells being of T-cell origin, which may secrete cytokines including tumour necrosis factor and interleukin-1, that are believed to be mediators in SIRS. In the absence of evidence of infection on microbiology and pathology, we postulate that the features of SIRS in this patient was due to the disseminated malignancy itself.

The impact of T-cell depletion on the effects of HLA DR beta 1 and DQ beta allele matching in HLA serologically identical unrelated donor bone marrow transplantation

Unrelated donor bone marrow transplants have been associated with relatively high rates of acute graft-vs.-host disease and treatment-related mortality. These complications reflect histo-incompatibility between donor and recipient. Molecular technology has recently been applied to HLA typing to identify alleles not distinguishable with serologic typing techniques. We report results in 92 unrelated marrow transplant recipients who were HLA seroidentical with donor HLA-A, -B, and -DR antigens and assess the effect of DR beta 1 and DQ beta compatibility using sequence specific oligonucleotide primers. Forty-eight patients received T-cell depleted marrow grafts, and 44 received unmodified grafts. Among recipients of unmodified marrow grafts, matching for both DR beta 1 and DQ beta reduced the rate of grade 3-4 acute graft-vs.-host disease to 38 +/- 20% vs. 73 +/- 20% among recipients mismatched for either allele (p = 0.02). This difference was not observed in recipients of T-cell depleted marrow grafts. Multivariate analysis confirmed matching for both DR beta 1 and DQ beta loci (p = 0.015), and receiving a T-cell depleted graft (p = 0.008) independently predicted for reduced risk of grade 3-4 acute graft-vs.-host disease. In conclusion, both DR beta 1 and DQ beta appear biologically important for development of acute graft-vs.-host disease in patients receiving unmanipulated marrow grafts for unrelated donor transplant.

RF heating of implanted spinal fusion stimulator during magnetic resonance imaging

Radio frequency (RF) heating of an implanted spinal fusion stimulator (SpF) during magnetic resonance imaging (MRI) was studied on a full-size human phantom. Heating during MRI scans (GE Signa 4X, 1.5 T) was measured with RF-transparent fiberoptic sensors. With the implant correctly connected, the maximum temperature rises were less than 2 degrees C during the 26 min that the scans were at maximum RF power. At the tip of a broken stimulator lead (connecting the SpF generator and its electrodes), the maximum temperature rise was 11-14 degrees C. Regular 4-min scans of the spinal cord produced similar temperature rises at the broken tip. After the generator and the leads were removed, heating at the electrode connector tip was less than 1.5 degrees C. The control temperature rises at the same locations, without the stimulator, were less than 0.5 degree C. This study shows that spinal fusion stimulator heating is within the Food and Drug Administration safety guideline of 2 degrees C. However, if a lead wire is broken, it is unsafe during MRI scans. Radiological examinations will be necessary to ensure the integrity of the implant.

Specific regions of heteromeric subunits involved in enhancement of G protein-gated K+ channel activity

Heterologous coexpression of recombinant, G protein-gated, inwardly rectifying K+ (GIRK) channel subunits has yielded large currents, severalfold greater than those obtained from expression of the individual subunits. Such current enhancement has been obtained from coexpression of the inactive GIRK1 subunit with the low activity GIRK2-5 subunits in Xenopus oocytes. Using deletion and chimeric constructs, we now report the identification of a C-terminal region unique to GIRK1 and a larger central region of GIRK4 highly homologous to GIRK1, both of which are critical for production of large currents. Chimeras containing these two regions produced homomeric channels, exhibiting currents severalfold greater than those from either wild-type subunit alone. G protein regulation of such chimeric channel currents resembled that of wild-type currents. Green fluorescent protein-tagged channels showed that the amount of chimeric channel expressed on the oocyte cell surface was similar to its wild-type counterpart, suggesting that the enhanced activity was not due to differences in relative levels of expression but rather to the coexistence of the chimeric regions. Single-channel recordings of the active chimeras exhibited patterns of activities with open-time kinetics and conductance characteristics representative of those of GIRK4, indicating that the presence of the GIRK1 C-terminal region caused an increase in the frequency of channel openings without affecting their duration.

Molecular evolution of vertebrate VIP receptors and functional characterization of a VIP receptor from goldfish Carassius auratus

Vasoactive intestinal polypeptide (VIP) is a neuropeptide that has numerous physiological actions and is widely distributed in the body. However, as yet, there is no sequence information about VIP receptors in lower vertebrates. Partial cDNA fragments spanning transmembrane domains 2 to 6 of VIP receptors were isolated from six nonmammalian vertebrate species, including chicken, pigeon, frog, lizard, salmon, and goldfish. Sequence comparison of these receptors revealed essential structural motifs responsible for receptor function. In addition, the first nonmammalian full-length VIP receptor cDNA was obtained by screening a goldfish brain and pituitary cDNA library. Functional expression of this receptor in mammalian COS-7 cells showed that it is coupled to cAMP production in a VIP and PACAP concentration-dependent manner; the EC50 of VIP was determined to be 1 nM. At 100 nM peptide, the relative potency of various peptides in stimulating cAMP in the transfected cells was VIP > PACAP > GHRH = secretin > PHM > PTH > glucagon > GLP-1 > GIP. Characterization of the VIP receptors in lower vertebrates should enhance our understanding of the molecular evolution and physiology of VIP in vertebrates.

Inflammatory pseudotumor of epididymis and Epstein-Barr virus: a study of two cases

Inflammatory pseudotumor (IP) is an uncommon tumor-like lesion of unknown etiology. Two cases of IP of the epididymis were identified in our hospital file. Having read a recent report on finding Epstein-Barr virus (EBV) in some cases of IP in lymph node, spleen and liver, the two cases of epididymal IP were tested for EBV-encoded small nuclear RNA 1 and 2 by in-situ hybridization. The absence of EBV RNA suggests that IP of epididymis may be etiologically distinct from that occurring in the organs of the reticuloendothelial system.

Magnitude of tolerance to fentanyl is independent of mu-opioid receptor density

The effect of a mu-opioid receptor irreversible antagonist on the development of tolerance to fentanyl was determined in mice. Mice were injected with saline or clocinnamox (3.2 mg/kg, i.p.) and 4 h later mice implanted s.c. with a placebo pellet or an osmotic minipump that infused fentanyl (0.165 mg/kg per day) for 3 days. Fentanyl pumps and placebo pellets were removed on the third day following implantation and 4 h later mu-opioid receptor saturation binding studies in whole brain ([3H][D-Ala2,MePhe4,Gly-ol5]enkephalin: DAMGO) or fentanyl analgesic dose-response studies (tailflick assay) were conducted. Fentanyl infusions and clocinnamox both significantly reduced the potency of fentanyl by 2.8- and 2.4-fold, respectively. When fentanyl and clocinnamox were administered together, a significant 5.0-fold reduction in fentanyl potency relative to the saline-placebo group was observed, which represents an additive effect of clocinnamox and fentanyl. The ED50 of fentanyl in clocinnamox-treated mice was shifted 2.1-fold by fentanyl infusion relative to the clocinnamox-placebo group. This is comparable to the 2.8-fold shift in the ED50 produced by fentanyl infusion in saline-treated mice. In binding studies, fentanyl produced a small (-9%) reduction in Bmax, while clocinnamox significantly reduced (-41%) mu-opioid receptor density without altering affinity (Kd). In the clocinnamox-fentanyl group, there was a 50% reduction in Bmax, which is similar to the additive effect observed in analgesia studies. These data indicate that changes in mu-opioid receptor density prior to the development of tolerance to fentanyl do not impact on the magnitude of tolerance.

Jaffee v. Redmond: making the courts a tool of injustice?

In July, 1996, the United States Supreme Court held in Jaffee v. Redmond that statements made to a psychotherapist are privileged communications in a federal action. Prior to Jaffee, the federal courts were not in agreement as to whether this privilege existed. The majority found strong public and private interests that were furthered by recognition of the privilege. The minority, however, reasoned that the "occasional injustices" due to the exclusion of evidence made the courts a tool of injustice. Although the privilege is now recognized in federal courts, its contours and exceptions remain to be decided on a case by case basis.

Differences in dose scheduling as a factor in the etiology of anthracycline-induced cardiotoxicity in Ewing sarcoma patients

Clinical observation suggested a high prevalence of cardiac morbidity and mortality in children with Ewing sarcoma (ES) treated at B.C.'s Children's Hospital. We therefore compared 30 patients treated for Ewing sarcoma between 1978 and 1991 with 26 soft tissue sarcoma (STS) patients treated with similar chemotherapy over the same period of time. All patients were evaluated for cardiac function using echocardiography. Shortening fraction (SF) and left ventricular mass index (Massl) were compared before and after treatment. The role of chest irradiation, dose concentration (DC) of adriamycin (AD), total mean doses of AD, cyclophosphamide (CY) and actinomycin (AC) were analysed. SF for patients with ES and STS postchemotherapy was significantly lower (P < .001 and P = 0.0004, respectively) than pretreatment values. Postchemotherapy SF for ES was lower than STS (P = 0.0097). Massl for each group did not change significantly. Six of the ES patients had postchemotherapy SF of < 0.20, with three in congestive failure, two cardiac deaths and one heart transplant. One additional ES patient had sick sinus syndrome and needed a pacemaker. Among the STS patients only one had SF < .20 and none were symptomatic. There were no significant differences in the mean AD, CY and AC doses for ES versus STS. The difference in the DC of AD for ES (mean 744) compared to STS (mean = 362) was significant (P = < 0.001). Regression analysis indicated a trend for decreasing SF with increasing DC (P = 0.017). Chest irradiation did not appear to increase the likelihood of cardiotoxicity. ES patients had a higher prevalence of cardiac dysfunction compared to STS. Studies are required to evaluate the importance of the components of DC, i.e., size of the individual dose and frequency of administration of AD, and to look at other possible factors in the causation of cardiomyopathy in ES.

Control of channel activity through a unique amino acid residue of a G protein-gated inwardly rectifying K+ channel subunit

G protein-gated inwardly rectifying K+ (GIRK) channels, which are important regulators of membrane excitability both in heart and brain, appear to function as heteromultimers. GIRK1 is unique in the GIRK channel family in that although it is by itself inactive, it can associate with the other family members (GIRK2-GIRK5) to enhance their activity and alter their single-channel characteristics. By generating a series of chimeras, we identified a phenylalanine residue, F137, in the pore region of GIRK1 that critically controls channel activity. F137 is found only in GIRK1, while the remaining GIRK channels possess a conserved serine residue in the analogous position. The single-point mutant GIRK4(S143F) behaved as a GIRK1 analog, forming multimers with GIRK2, GIRK4, or GIRK5 channels that exhibited prolonged single-channel open-time duration and enhanced activity compared with that of homomultimers. Expression of the corresponding GIRK1 (F137S) mutant alone resulted in appreciable channel activity with novel characteristics that was further enhanced upon coexpression with other GIRK subunits. Thus, although the F137 residue renders the GIRK1 subunit inactive, when combined with other GIRK heteromeric partners it alters their gating and contributes to their enhanced activity.

Long-term efficacy of ribavirin plus interferon alfa in the treatment of chronic hepatitis C

BACKGROUND & AIMS

Sustained response to interferon treatment for chronic hepatitis C is unsatisfactory. This study examined whether combining interferon alfa with ribavirin induces a better sustained efficacy than interferon alone in the treatment of chronic hepatitis C.

METHODS

Sixty noncirrhotic patients with chronic hepatitis C were randomly assigned to three groups. Group 1 received 1200 mg oral ribavirin daily plus 3 million units of recombinant interferon alfa 2a thrice weekly for 24 weeks, group 2 received the same dose of interferon alfa 2a alone for 24 weeks, and group 3 received no treatment. The patients were then followed up for an additional 96 weeks.

RESULTS

At the end of treatment, a complete response (normal serum alanine aminotransferase level and undetectable serum hepatitis C virus RNA) was achieved in 16 of the 21 patients in group 1 (76%), as compared with 6 of 19 in group 2 (32%) and none in group 3. At 96 weeks after the end of treatment, patients in group 1 sustained a higher complete response rate than patients in group 2 (43% vs. 6%).

CONCLUSIONS

Combined treatment with ribavirin and interferon alfa 2a for 24 weeks is more effective than interferon alfa 2a alone for the treatment of chronic hepatitis C. The biochemical and virological responses were sustained in about one half of the treated patients for at least 2 years after cessation of the therapy.