14-3-3 proteins regulate cullin 7-mediated Eag1 degradation

BACKGROUND

Mutations in the human gene encoding the neuron-specific Eag1 (K_V10.1; KCNH1) potassium channel are linked to congenital neurodevelopmental diseases. Disease-causing mutant Eag1 channels manifest aberrant gating function and defective protein homeostasis. Both the E3 ubiquitin ligase cullin 7 (Cul7) and the small acid protein 14-3-3 serve as binding partners of Eag1. Cul7 mediates proteasomal and lysosomal degradation of Eag1 protein, whereas over-expression of 14-3-3 notably reduces Eag1 channel activity. It remains unclear whether 14-3-3 may also contribute to Eag1 protein homeostasis.

RESULTS

In human cell line and native rat neurons, disruptions of endogenous 14-3-3 function with the peptide inhibitor difopein or specific RNA interference up-regulated Eag1 protein level in a transcription-independent manner. Difopein hindered Eag1 protein ubiquitination at the endoplasmic reticulum and the plasma membrane, effectively promoting the stability of both immature and mature Eag1 proteins. Suppression of endogenous 14-3-3 function also reduced excitotoxicity-associated Eag1 degradation in neurons. Difopein diminished Cul7-mediated Eag1 degradation, and Cul7 knock-down abolished the effect of difopein on Eag1. Inhibition of endogenous 14-3-3 function substantially perturbed the interaction of Eag1 with Cul7. Further structural analyses suggested that the intracellular Per-Arnt-Sim (PAS) domain and cyclic nucleotide-binding homology domain (CNBHD) of Eag1 are essential for the regulatory effect of 14-3-3 proteins. Significantly, suppression of endogenous 14-3-3 function reduced Cul7-mediated degradation of disease-associated Eag1 mutant proteins.

CONCLUSION

Overall these results highlight a chaperone-like role of endogenous 14-3-3 proteins in regulating Eag1 protein homeostasis, as well as a therapeutic potential of 14-3-3 modulators in correcting defective protein expression of disease-causing Eag1 mutants.

Identification of MKRN1 as a second E3 ligase for Eag1 potassium channels reveals regulation via differential degradation

Mutations in the human gene encoding the neuron-specific Eag1 voltage-gated K⁺ channel are associated with neurodevelopmental diseases, indicating an important role of Eag1 during brain development. A disease-causing Eag1 mutation is linked to decreased protein stability that involves enhanced protein degradation by the E3 ubiquitin ligase cullin 7 (CUL7). The general mechanisms governing protein homeostasis of plasma membrane- and endoplasmic reticulum (ER)-localized Eag1 K⁺ channels, however, remain unclear. By using yeast two-hybrid screening, we identified another E3 ubiquitin ligase, makorin ring finger protein 1 (MKRN1), as a novel binding partner primarily interacting with the carboxyl-terminal region of Eag1. MKRN1 mainly interacts with ER-localized immature core-glycosylated, as well as nascent nonglycosylated, Eag1 proteins. MKRN1 promotes polyubiquitination and ER-associated proteasomal degradation of immature Eag1 proteins. Although both CUL7 and MKRN1 contribute to ER quality control of immature core-glycosylated Eag1 proteins, MKRN1, but not CUL7, associates with and promotes degradation of nascent, nonglycosylated Eag1 proteins at the ER. In direct contrast to the role of CUL7 in regulating both ER and peripheral quality controls of Eag1, MKRN1 is exclusively responsible for the early stage of Eag1 maturation at the ER. We further demonstrated that both CUL7 and MKRN1 contribute to protein quality control of additional disease-causing Eag1 mutants associated with defective protein homeostasis. Our data suggest that the presence of this dual ubiquitination system differentially maintains Eag1 protein homeostasis and may ensure efficient removal of disease-associated misfolded Eag1 mutant channels.

Ca(2+)-binding protein centrin 4 is a novel binding partner of rat Eag1 K(+) channels

Eag1 is neuron-specific K(+) channel abundantly expressed in the brain and retina. Subcellular localization and physiological analyses in neurons reveal that Eag1 may participate in Ca(2+)-signaling processes in the synapse. Here, we searched for rat Eag1 (rEag1)-binding proteins that may contribute to Ca(2+) regulation of the K(+) channel. Yeast two-hybrid screening identified centrin 4, a member of the centrin family of Ca(2+)-binding proteins. GST pull-down and immunoprecipitation assays in brain and retina lysates confirm the interaction of centrin with rEag1 in neurons. Centrin 4 binds to rEag1 in the absence of Ca(2+). Raising Ca(2+) concentration enhances the association efficiency of centrin 4 and rEag1, and is required for the suppression of rEag1 currents by centrin 4. Altogether, our data suggest that centrin 4 is a novel binding partner that may contribute to Ca(2+) regulation of rEag1 in neurons.

14-3-3θ is a binding partner of rat Eag1 potassium channels

The ether-à-go-go (Eag) potassium (K(+)) channel belongs to the superfamily of voltage-gated K(+) channel. In mammals, the expression of Eag channels is neuron-specific but their neurophysiological role remains obscure. We have applied the yeast two-hybrid screening system to identify rat Eag1 (rEag1)-interacting proteins from a rat brain cDNA library. One of the clones we identified was 14-3-3θ, which belongs to a family of small acidic protein abundantly expressed in the brain. Data from in vitro yeast two-hybrid and GST pull-down assays suggested that the direct association with 14-3-3θ was mediated by both the N- and the C-termini of rEag1. Co-precipitation of the two proteins was confirmed in both heterologous HEK293T cells and native hippocampal neurons. Electrophysiological studies showed that over-expression of 14-3-3θ led to a sizable suppression of rEag1 K(+) currents with no apparent alteration of the steady-state voltage dependence and gating kinetics. Furthermore, co-expression with 14-3-3θ failed to affect the total protein level, membrane trafficking, and single channel conductance of rEag1, implying that 14-3-3θ binding may render a fraction of the channel locked in a non-conducting state. Together these data suggest that 14-3-3θ is a binding partner of rEag1 and may modulate the functional expression of the K(+) channel in neurons.

Waveforms of the ductus venosus blood flow in normal human fetuses aged 8-38 weeks

BACKGROUND

We attempted to establish normal Doppler flow velocity waveform patterns in the human fetal ductus venosus (DV), and also to establish a standardized measurement technique.

METHODS

Ductus venosus blood flow was measured in a prospective study involving 545 fetuses aged between 8 and 38 weeks in utero, the mothers of whom received prenatal care in Kaohsiung Chang Gung Memorial Hospital in a 12-month period in 1998-1999. Several DV hemodynamic parameters were assessed, including peak systolic velocity (DVP), peak systolic/diastolic (S/D) ratio, time-averaged velocity (TAMX), maximum velocity during atrial contraction (DVM), pulsatility index (PI), Pourcelot's resistance index (RI), and fetal heartbeat (FHB).

RESULTS

Technically acceptable ductus venosus blood flow velocity waveform patterns were collected from 490 of 545 pregnant women (89.9%). The mean +/- SD value for the peak systolic DV velocity during the time period of 8 to 38 weeks in utero was 0.33 +/- 0.11 meters/sec (m/s), the TAMX being 0.24 +/- 0.09 m/s. The maximum velocity during atrial contraction was 0.15 +/- 0.09 m/s, and the peak S/D velocity ratio was 2.5 +/- 1.01. The PI, Pourcelot's RI and fetal heart beat were, 0.67(+/- 0.21), 0.64 (+/- 0.11), and 163.3 (+/- 18.82 bpm), respectively. Significant increases in DVP, TAMX, and DVM with advancing gestational age were established, and decreases in PI, RI, S/D, and FHB with advancing gestational age were also observed.

CONCLUSIONS

Further investigation of DV hemodynamics throughout pregnancy may enable a greater understanding of normal placental perfusion, the fetal venous return to the heart and associated cardiac function.

Aprotinin, blood loss, and renal dysfunction in deep hypothermic circulatory arrest

BACKGROUND

The technique of deep hypothermic circulatory arrest (DHCA) for cardiothoracic surgery is associated with increased risk for perioperative blood loss and renal dysfunction. Although aprotinin, a serine protease inhibitor, reduces blood loss in patients undergoing cardiopulmonary bypass, its use has been limited in the setting of DHCA because of concerns regarding aprotinin-induced renal dysfunction. Therefore, we assessed the affect of aprotinin on both blood transfusion requirements and renal function in patients undergoing cardiovascular surgery and DHCA.

METHODS AND RESULTS

We reviewed the records of 853 patients who underwent aortic or thoracoabdominal surgery at Stanford University Medical Center between January 1992 and March 2000. Two hundred three of these patients were treated with DHCA, and 90% (183) survived for more than 24 hours. Preoperative patient characteristics and intraoperative and postoperative clinical and surgical variables were recorded, and creatinine clearance (CRCl) was calculated for the preoperative and postoperative periods; renal dysfunction was prospectively defined as a 25% reduction in CRCl. The association between perioperative variables, including aprotinin use, and renal dysfunction was assessed by ANOVA techniques. Total urine output was 1294+/-1024 mL and 3492+/-1613 mL during and after surgery, respectively. CRCl decreased significantly after DHCA from 86+/-8 mL/min (before surgery) to 67+/-4 mL/min (in the intensive care unit) (P<0.01). Thirty-eight percent of patients (70 of 183) had postoperative renal dysfunction. Multivariate regression analyses identified 5 factors independently associated with a >25% reduction in CRCl: requirement for >/=5 U of packed red blood cells(P=0.0002; OR=2.1), </=800 mL of urine collected in the operating room (P=0.0011; OR=1.9), nonuse of dopamine (P=0.0430; OR=1.6), hematocrit </=21 mg% (P=0.0343; OR=1.5), and </=2100 mL of urine during the first 24 hours in the intensive care unit (P=0.0039; OR=2.0). Aprotinin did not increase the likelihood of postoperative renal dysfunction (P=0.951), nor did it significantly reduce packed red blood cell transfusion requirements in either primary (n=107) (P=0.456) or reoperative cardiovascular (n=76) (P=0.176) procedures. During the operative period, the aprotinin group received a greater number of units of platelets (10.0 versus 6.6 U, P<0.012), fresh frozen plasma (4.8 versus 3.1 U, P<0.03), and cryoprecipitate (9.9 versus 5.4 U, P<0.002) than patients not prescribed aprotinin. Similarly, patients given aprotinin received more cryoprecipitate in the intensive care unit (7.3 versus 3.0 U, P<0.024).

CONCLUSIONS

These data suggest that the administration of aprotinin to patients treated with DHCA does not increase the risk of renal dysfunction. However, aprotinin may not ameliorate the problem of perioperative blood loss in DHCA. Patients with greater requirements for packed red blood cell transfusions or reduced urine production are more likely to have postoperative renal dysfunction. Dopamine may provide renal protection in the setting of DHCA.

Prenatal sonographic appearance of Beare-Stevenson cutis gyrata syndrome: two- and three-dimensional ultrasonographic findings

Beare-Stevenson cutis gyrata syndrome is characterized by craniofacial anomalies, particularly craniosynostosis, ear defects, cutis gyrata, acanthosis nigricans, anogenit anomalies, skin tags, and prominent umbilical stump. The prenatal two- and three-dimensional ultrasonographic findings of this rare condition is reported. The detection was made at 32 weeks of gestation in a woman with polyhydramnios and fetal head anomaly. The ultrasound appearance and postnatal follow-up are presented.

HER-2/neu gene amplification in stages I-IV breast cancer detected by fluorescent in situ hybridization

PURPOSE

Approximately 25-30% of breast and ovarian carcinomas have amplification of the HER-2/neu oncogene. The aim of the present study was to focus on HER-2/neu gene amplification in different clinical stages of breast cancer in order to (1) determine if fluorescent in situ hybridization (FISH) can be used to detect HER-2/neu gene amplification in different clinical stages of breast cancer, (2) establish whether HER-2/neu gene amplification characterizes a subset of breast cancer in each of these stages, and (3) determine whether a trend for correlation of amplification with the clinical stage of the disease can be detected using the FISH technology.

METHODS

A total of 40 specimens of formalin-fixed, paraffin-embedded breast cancer tissues were analyzed cytogenetically, in a blinded fashion, for HER-2/neu gene amplification using FISH and the Vysis LSI HER-2/neu Orange and CEP 17 Green DNA dual color probe. The criterion for "high amplification" was an amplification ratio of >4.0, that for "moderate amplification" a ratio between 2.1 and 4.0, and that for "low amplification" a ratio of 1.5-2.0.

RESULTS

Using a cutoff point of > or =1.5, the overall frequency of HER-2/neu gene amplification among stage I tumors was 30% (3 out of 10). Of these, one-third (1 out of 3) showed low amplification, one-third (1 out of 3) were moderately amplified, and one-third (1 out of 3) were highly amplified. The overall frequency of HER-2/neu gene amplification among stage II tumors was 0% (0 out of 10). The overall frequency of HER-2/neu gene amplification among stage III tumors was 10% (1 out of 10). The sole tumor found positive was classified as moderately amplified by our criteria. The overall frequency of HER-2/neu gene amplification among stage IV tumors was 50% (5 out of 10). Four of the 5 tumors found positive were highly amplified. The overall frequency of gene amplification in the 40 cases studied was 22.5% (9 out of 40 tumors studied).

CONCLUSION

Although a linear correlation between HER-2/neu amplification and clinical stage cannot be established at this time, it is interesting to note that when stages I and II, and when stages III and IV are combined, respectively, the latter category has a higher amplification frequency than the former. Furthermore, stage IV has the highest frequency (5 out of 10) of HER-2/neu gene amplification than all three lower stages combined (4 out of 30). This is no doubt due to the high frequency of gene amplification observed in stage IV tumors, which, interestingly, also demonstrate high level amplification of HER-2/neu gene copy numbers. Although the biologic and clinical basis for gene amplification is not clear, given the observation that the most aggressive disease stage is associated with the highest frequency of gene amplification and the most high level amplification, further exploration of HER-2/neu as a prognostic marker of poor outcome using FISH is warranted.

Sorcin associates with the pore-forming subunit of voltage-dependent L-type Ca2+ channels

Intracellular Ca2+ release in muscle is governed by functional communication between the voltage-dependent L-type Ca2+ channel and the intracellular Ca2+ release channel by processes that are incompletely understood. We previously showed that sorcin binds to cardiac Ca2+ release channel/ryanodine receptors and decreases channel open probability in planar lipid bilayers. In addition, we showed that sorcin antibody immunoprecipitates ryanodine receptors from metabolically labeled cardiac myocytes along with a second protein having a molecular weight similar to that of the alpha1 subunit of cardiac L-type Ca2+ channels. We now demonstrate that sorcin biochemically associates with cardiac and skeletal muscle L-type Ca2+ channels specifically within the cytoplasmically oriented C-terminal region of the alpha1 subunits, providing evidence that the second protein recovered by sorcin antibody from cardiac myocytes was the 240-kDa L-type Ca2+ channel alpha1 subunit. Anti-sorcin antibody immunoprecipitated full-length alpha1 subunits from cardiac myocytes, C2C12 myotubes, and transfected non-muscle cells expressing alpha1 subunits. In contrast, the anti-sorcin antibody did not immunoprecipitate C-terminal truncated forms of alpha1 subunits that were detected in myotubes. Recombinant sorcin bound to cardiac and skeletal HIS6-tagged alpha1 C termini immobilized on Ni2+ resin. Additionally, anti-sorcin antibody immunoprecipitated C-terminal fragments of the cardiac alpha1 subunit exogenously expressed in mammalian cells. The results identified a putative sorcin binding domain within the C terminus of the alpha1 subunit. These observations, along with the demonstration that sorcin accumulated substantially during physiological maturation of the excitation-contraction coupling apparatus in developing postnatal rat heart and differentiating C2C12 muscle cells, suggest that sorcin may mediate interchannel communication during excitation-contraction coupling in heart and skeletal muscle.

Quantitation of HER-2/neu and c-myc gene amplification in breast carcinoma using fluorescence in situ hybridization

HER-2/neu and c-myc amplification or overexpression have been reported to be associated with poor prognosis in breast carcinoma. The prognostic significance, however, remains somewhat controversial, partly because of discrepancies among different methodologies used for detection of the oncogene amplification or overexpression. Fluorescence in situ hybridization (FISH) has recently been shown to be a useful technique for analyzing genetic alterations in interphase nuclei in various tumors. In this study, FISH was used to quantitate HER-2/ neu and c-myc gene amplification in touch preparations of frozen tissue from 100 node-negative breast carcinomas. HER-2/neu amplification was found to be associated with an abnormal DNA index (P < .001) and tumor size (P < .04). Amplification of c-myc was associated with S phase (P < .0003), abnormal DNA index (P < .003), and a negative estrogen receptor status (P < .01). The coamplification of both oncogenes was strongly associated with an abnormal DNA index (P < .0001) and with tumor size (P < .009). The use of FISH for detection of HER-2/neu gene amplification was 92% concordant with immunocytochemistry (ICC) used for detection of overexpression of HER-2/neu protein. Fifteen of the 100 cases were both amplified for HER-2/neu by FISH and positive by ICC analysis. Seven cases without HER-2/neu gene amplification demonstrated HER-2/neu protein overexpression by ICC. One HER-2/neu-amplified case was negative by ICC. Repeat analysis of a subset of cases showed FISH to be a more reproducible method than ICC in the analysis of HER-2/neu in touch preparations of breast carcinoma. FISH is a rapid and reproducible method that allows the accurate measurement of the level of oncogene amplification within interphase nuclei. The use of FISH should provide a more accurate assessment of the prognostic significance of oncogene amplification in breast carcinoma.

Chromosome-specific aneusomy in carcinoma of the breast

Fluorescence in situ hybridization was performed on touch preparations from 55 primary infiltrating ductal carcinomas of the breast to determine numeric chromosome abnormalities. The frequency of aneusomy, measured by both nondisomy and chromosomal gain, was determined for chromosomes X, 4, 6-12, 17, and 18 with the use of chromosome-specific, alpha-satellite DNA probes. The presence of chromosome-specific numeric abnormalities was correlated with established clinicopathological parameters, including tumor size, lymph node involvement, tumor grade, estrogen receptor level, and menopause status. In addition, a case-control study was performed to explore a possible association between chromosome-specific aneusomy and recurrence in lymph-node-negative patients. Although chromosomes 8 and 6 were most frequently aneusomic, numeric abnormalities of chromosomes 4 and 11 were most strongly associated with established prognostic factors. For chromosomes 4 and 11, strong associations were found with tumor involvement of lymph nodes and increased tumor size, along with a weaker association with tumor grade. In addition, numeric abnormalities of the following chromosomes were associated with the corresponding prognostic factors: chromosomes X, 7, and 12 with lymph node status; chromosomes 10, 17, and 6 with tumor size; and chromosomes 7, 12, 17, and X with tumor grade. No correlations were observed with estrogen receptor level or menopause status. In the case-control study performed on isolated nuclei of paraffin-embedded tissue from lymph node-negative breast cancer patients (19 cases and 19 controls), the gain of chromosome 4 was correlated with disease progression. These findings suggest that chromosome-specific aneusomy is associated with certain established prognostic factors and may be associated with disease progression.

Fluorescence in situ hybridization: powerful molecular tool for cancer prognosis

We review several aspects of fluorescence in situ hybridization (FISH) technology that demonstrate its breadth and power in detecting and monitoring genetic abnormalities associated with cancers. The clinical utility of FISH in disease management is demonstrated in several examples, including trisomy 8 detection with high specificity and sensitivity in patients with myeloid leukemias; trisomy 12 detection with higher efficiency than conventional cytogenetics in patients with chronic lymphocytic leukemia; assessment of engraftment success, chimerism, and relapse in opposite sex bone marrow transplantation; and correlation of trisomy 7 with survival time in patients with prostate tumors. Advances in FISH technology include multicolor analyses, which permit the simultaneous detection of several genetic abnormalities by using cohybridization of probes labeled with several fluorescent labels or label combinations, and comparative genomic hybridization, a relatively new method whereby a single hybridization can reveal aberrations across the entire genome.

Fluorescence in situ hybridization: powerful molecular tool for cancer prognosis

We review several aspects of fluorescence in situ hybridization (FISH) technology that demonstrate its breadth and power in detecting and monitoring genetic abnormalities associated with cancers. The clinical utility of FISH in disease management is demonstrated in several examples, including trisomy 8 detection with high specificity and sensitivity in patients with myeloid leukemias; trisomy 12 detection with higher efficiency than conventional cytogenetics in patients with chronic lymphocytic leukemia; assessment of engraftment success, chimerism, and relapse in opposite sex bone marrow transplantation; and correlation of trisomy 7 with survival time in patients with prostate tumors. Advances in FISH technology include multicolor analyses, which permit the simultaneous detection of several genetic abnormalities by using cohybridization of probes labeled with several fluorescent labels or label combinations, and comparative genomic hybridization, a relatively new method whereby a single hybridization can reveal aberrations across the entire genome.

Interphase cytogenetics of renal cortical neoplasms. Correlation with DNA ploidy by flow cytometry

The genotypic changes in 22 renal cortical neoplasms and 16 of the corresponding normal kidney tissues by fluorescence in situ hybridization (FISH) were studied using directly labelled probes for chromosomes 7, 8, 10, 11, 12, 17, 18, X, and Y, and by flow cytometry (FCM). DNA ploidy analysis revealed 8 DNA aneuploid and 14 DNA diploid neoplasms. The mean single spot hybridization in normal kidney was 5 +/- 0.9% for chromosomes 7, 8, 10, 11, 12, and the X in females. The mean single spot hybridization for chromosomes 17 and 18 was 14.9% and 18.5%, respectively. The mean number of more than two (> 2) hybridization signals in normal kidney cells for all autosomes and the X-chromosome in females was 3 +/- 1.2%. Significant chromosomal loss was restricted to chromosomes 8, 18, X, and Y. The net chromosomal gain and loss correlated with the DIs in aneuploid tumors. All DNA diploid neoplasms showed both chromosomal loss and gain with a tendency to a net loss. No apparent correlation between the chromosomal aberrations and the clinicopathologic factors was found in this cohort. Our study demonstrates that: (1) tissue specific controls may provide better information for definable performance criteria for this technique; (2) monosomy can more reliably be assessed on fresh samples; (3) chromosomal loss is confined to certain chromosomes; (4) DNA diploid tumors manifest heterogeneous gain and loss of various chromosomes with a tendency to a net loss; and (5) integrated FISH and FCM analysis provide more information on the chromosomal abnormalities of these neoplasms.

Effect of leuprolide acetate in patients with moderate to severe functional bowel disease. Double-blind, placebo-controlled study

Moderate to severe functional bowel disease results in debilitating abdominal pain, nausea, intermittent vomiting, early satiety, bloating, abdominal distension, and/or altered bowel habits. Because it occurs approximately 20-30 times more frequently in women than in men and its symptoms often coincide with the menstrual cycle, we hypothesized that reproductive steroids may antagonize diseased nerves of the gastrointestinal tract, enhancing the expression of symptoms. No effective or consistent therapy has existed for these patients. We prospectively investigated the effect of a gonadotropin-releasing hormone analog, leuprolide acetate, in 30 women with symptoms of moderate to severe functional bowel disease. The study was phase II, randomized, double blind, and placebo controlled. Lupron Depot 3.75 mg (which delivers a continuous low dose of drug for one month) or placebo were given intramuscularly monthly for three months. Symptom scores were assessed at each four-week visit. Follicle-stimulating hormone, luteinizing hormone, estradiol, and progesterone levels were assessed before and after therapy. Patients treated with low-dose leuprolide improved progressively and significantly in scores for nausea, vomiting, bloating, abdominal pain, and early satiety, and for overall symptoms (P < 0.01-0.05). All hormone levels decreased significantly (P < 0.05) except luteinizing hormone (P = 0.054).

Analysis of adverse events in a dose titration study

The authors have examined the analysis of adverse event data from an efficacy dose escalation trial. Unlike the analysis of efficacy data, the assumption that when a patient experiences an adverse event at a given dose, he or she will experience the same at a greater dosage level was not applicable in the analysis of adverse event data. Because the time effect is confounded with the dose effect in a dose escalation design, any assessment of a dose-effect relationship from such a scheme is found to be preliminary and suspect. For drugs that need to be dosed with a titration schedule, a time-dose-specific incidence of an adverse event provides more useful information than a dose-specific incidence. The pace of dose titration, which was found to be important in the manifestation of an adverse event, also needs to be specified. These aspects are illustrated with data from a specially designed trial. The entire study contained a placebo arm and three arms of an active drug randomized in a parallel comparative fashion. Within each of the three active drug arms, a forced titration scheme was used to raise the dose to different levels, which distinguished the three arms. With an efficacy dose titration design, the dose-response relationship for adverse events cannot be determined without incorporating a placebo arm and other arms with different maximum allowable doses. For drugs that need to be administered with a titration scheme, incidence of adverse events needs to be presented with the dosage, the time, and the pace of titration.

An integrated design for dose comparison trials

An integrated design, which incorporates the dose titration scheme into the parallel comparative design, is proposed for dose comparison trials of drugs that may cause a first-dose phenomenon. This design includes a concurrent placebo control group, thereby providing valid estimate of drug effect. The other groups are defined by the maximum allowable dose. Except for the maximum allowable dose, both the titration schedule and the titration interval are standardized. The effect of the pace of titration is thus controlled. In extreme cases, all patients need only the lowest dose tested, and all patients need the highest dose tested to achieve the required efficacy response. In nonextreme cases, this design answers questions that are usually asked of dose comparative trials: overall drug effects, adequacy of starting dose, effects of dose increment, maximum effective dose, dose-response relationship, and time effect. Because both efficacy and safety analyses can be performed similarly, risk-benefit analysis thus can be evaluated in the same group of patients, and an optimum titration regimen may be determined rationally.

Autoimmunity to a 28-30 kD cell membrane DNA binding protein: occurrence in selected sera from patients with SLE and mixed connective tissue disease (MCTD)

Previous experiments have established the presence of a 30-kD DNA binding protein on the surface of human leukocytes. Herein we report that selected sera from patients with systemic lupus erythematosus (SLE) and MCTD are reactive with a 28-30 kD protein on immunoblots of peripheral blood mononuclear cells (PBMC) cell membrane preparations; the reactivity is abolished by prior incubation of the blot with DNA. Antibodies eluted from the 28-30 kD strip inhibited the binding of 3H. DNA to human PBMC. An immunomatrix of 28-30 kD reactive immunoglobulins was able to extract a 29-kD DNA binding protein from a PBMC cell membrane preparation. Flow cytometry experiments confirmed the cell surface IgG reactivity of sera with T lymphocytes. Additional experiments indicated that cell surface IgG binding was not due to antibodies binding to cell surface DNA, DNA anti-DNA immune complexes reacting with a DNA binding protein, anti-histone antibodies or anti-Sm antibodies. It is hypothesized that this autoimmune response could be one component of an idiotypic network involving anti-DNA antibodies.

Mapping of the C3b-binding site of CR1 and construction of a (CR1)2-F(ab')2 chimeric complement inhibitor

CR1/CR2 chimeric receptors in which various short consensus repeats (SCRs) of CR1 were attached to CR2 were transiently expressed on COS cells, and assessed for the binding of polymerized C3b (pC3b) and anti-CR2 by immunofluorescence. Of COS cells expressing chimeras containing SCR 1-4, 1-3, 2-4, 1-2, and 2-3 of the long homologous repeats (LHRs) -B or -C, 96%, 66%, 23%, 0%, and 0%, respectively, bound pC3b. K562 cells were stably transfected with wild-type CR1, deletion mutants of CR1, and the CR1/CR2 chimeras, respectively, and assayed for binding of 125I-pC3b. The dissociation constants (Kd) for pC3b of wild-type CR1 and the LHR-BD and -CD constructs were in the range of 1.0-2.7 nM, and of the CR1/CR2 chimeras containing SCRs 1-4, 1-3, and 2-4 of LHR-B or -C were 1.8-2.4, 6-9, and 22-36 nM, respectively. The factor I-cofactor function of the CR1/CR2 chimeras paralleled the C3b-binding function of the constructs. A CR1/immunoglobulin (Ig) chimeric protein was prepared by fusing SCRs 1-4 of LHR-B to the heavy chains of a murine F(ab')2 anti-nitrophenacetyl (NP) monoclonal antibody. The (CR1)2-F(ab')2 chimera, which retained its specificity for NP, was as effective as soluble, full-length CR1 in binding pC3b, serving as a cofactor for factor I-mediated cleavage of C3b, and inhibiting activation of the alternative pathway, indicating that the bivalent expression of these SCRs reconstitutes the alternative pathway inhibitory function of CR1. The feasibility of creating CR1/Ig chimeras makes possible a new strategy of targeting complement inhibition by the use of Ig fusion partners having particular antigenic specificities.

Dose-response range of encainide for benign and potentially lethal ventricular arrhythmias

A multicenter, 2-week, double-blind, placebo-controlled, parallel group study was performed to determine the dose-response relation of encainide administered 3 times daily and to determine its onset of action. To be included in the study, patients with benign or potentially lethal ventricular arrhythmias were required to have an average of at least 30 ventricular premature complexes (VPCs) per hour on 48-hour Holter monitoring after a 48-hour washout period without antiarrhythmic drug treatment. Patients were randomly assigned to receive either placebo or 10, 25 or 50 mg of encainide 3 times daily (tid) for 2 weeks. Of the 125 patients who entered the study, 122 were available for efficacy analysis. Efficacy was determined using 24-hour Holter monitoring on days 1, 7 and 14. There was no difference in frequency of VPCs or of ventricular tachycardia events in the placebo and 10-mg-tid encainide arms. At doses of 25 and 50 mg of tid, encainide was effective in suppressing VPCs and in reducing the number of episodes of ventricular tachycardia. A positive dose-response relation was identified. The onset of effect of encainide was apparent at 3 hours and lasted for 24 hours with tid dosing. No difference in on-therapy conditions were found among the 4 study arms. No patients were discontinued from the study because of electrocardiographic changes. There was no statistically significant change in vital signs or physical examination data. In 1 patient an elevated serum glucose level developed. No symptomatic proarrhythmic events occurred and none required discontinuation of study medication.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Suanzaorentang on behavior changes and central monoamines

Previously, it was found that the ancient Chinese remedy of Suanzaorentang could be a promising anxiolytic drug (Chen and Hsieh, 1985a, Chen and Hsieh, 1985b). To understand the mechanism of the action of Suanzaorentang, the effects of Suanzaorentang on behavior changes and central monoamines and their metabolites were studied in rats. It was found that Suanzaorentang significantly (1) prolonged the period from the onset of clonic to tonic convulsions induced by pentylenetetrazol or picrotoxin, (2) prolonged the sleep duration induced by hexobarbital, (3) reduced locomotor activity, (4) enhanced the hypomotility induced by alpha-MT, (5) reduced the locomotor stimulation produced by levodopa plus benserazide, and (6) reduced central HVA, VMA, and 5-HIAA, but had no significant effects on central DA, NA, and 5-HT. These facts implied that Suanzaorentang decreased the turnover rate of central monoamines and central catecholaminergic activity.

Comparative study of encainide and quinidine in the treatment of ventricular arrhythmias

The antiarrhythmic efficacy and safety of oral encainide hydrochloride and quinidine sulfate were compared in a nine center double-blind crossover study in 187 outpatients with benign or potentially lethal ventricular arrhythmias. Patients with at least 30 premature ventricular complexes/h were randomized to receive either encainide, 25 mg four times/day, or quinidine, 200 mg four times/day, for 2 weeks. These doses were continued for another 2 weeks if a 75% or greater reduction in premature ventricular complexes was observed. If this reduction was not seen, encainide was increased to 50 mg four times/day or quinidine to 400 mg four times/day for an additional 2 weeks. Both drugs produced a statistically significant reduction in premature ventricular complex frequency compared with baseline values. Encainide produced a statistically significant greater mean reduction in total premature ventricular complexes than did quinidine during the initial dose phase and after dose adjustment. More patients required dose increases of quinidine (60%) than of encainide (51%). Early discontinuation of treatment resulting in advancement to the next study period occurred in 12 patients taking encainide and 38 patients taking quinidine (p less than 0.05). PR and QRS intervals increased significantly during encainide treatment, as did QTc and JT intervals during quinidine treatment. No adverse reactions resulted from these electrocardiographic changes. Adverse reactions were more common with quinidine than with encainide.(ABSTRACT TRUNCATED AT 250 WORDS)

Multivariate analysis of pacemaker patient survivorship

Multiple risk factors of patient mortality need to be evaluated and combined to serve practical purposes. A multivariate statistical model is illustrated here with a large data set and a simulated example. The piecewise parametric model is shown to be simple, efficient, and is suggested to be a good tool for routine usage. The approach should provide a more concise characterization of mortality in terms of multiple risk factors. The results of data analysis also provide a good reference for further explorations.

Prognostic factors in the survival of 1,484 stroke cases observed for 30 to 48 months. II. Clinical variables and laboratory measurements

Using the life table method, 962 cases of infarction, 279 cases of hemorrhage, and 243 cases of undetermined type of stroke, occurring in Manitoba between Jan 1, 1970, and June 30, 1971, were analyzed for factors affecting survival. Survival until Dec 31, 1973, was found to be adversely affected by the presence of coma or unconsciousness and the absence of localizing signs and symptoms. Also, the prognosis was poor if the heart was enlarged on the x-ray film or the ECG was abnormal. On the other hand, the presence of individual clinical entities such as hypertension, hypertensive heart disease, myocardial infarction, atrial fibrillation, or diabetes did not affect the survival significantly. These findings will help in predicting the prognosis and in planning for management of stroke cases.

Prognostic factors in the survival of 1,484 stroke cases observed for 30 to 48 months. I. Diagnostic types and descriptive variables

Survival and factors affecting survival were studied in 1,484 new cases of acute definite stroke occurring between Jan 1, 1970, and June 30, 1971, in Manitoba. The 962 infarctions, 279 hemorrhages, and 243 unidentified strokes were ascertained from hospital claim reports. Personal, clinical, and laboratory data were collected from hospital medical records, death certificates, and autopsy reports. Cases were followed up until Dec 31, 1973, to determine survival. Survival was significantly better in infarction than in hemorrhage, in subarachnoid hemorrhage than in intracerebral hemorrhage, in men than in women, in the young than in the old, in the married than in the single, in hemorrhage cases from rural areas than from urban areas, and in those discharged home than in those transferred to long-term care hospitals. These data may help in predicting the outcome of stroke and in planning for more efficient care.

Relation of body weight to development of ischemic heart disease in a cohort of young North American men after a 26 year observation period: the Manitoba Study

The role of overweight as a risk factor for ischemic heart disease remains controversial. Therefore, in the Manitoba Study of a cohort of 3,983 men with a mean age at entry of 30.8 years, initial measurements of body weight, represented by body mass index (weight/height2), were compared with the 26 year incidence of ischemic heart disease. After adjustment for the effects of age and blood pressure in univariate and multivariate analysis, body mass index was a significant predictor of the 390 cases of ischemic heart disease. To elucidate this relation further, the cohort was further analyzed after categorization by age at entry, time of occurrence of disease after entry and manifestation of ischemic heart disease. The association with weight was most apparent in men less than 40 years of age and was not evident until 16 years of follow-up. A high body mass index was significantly associated with development of myocardial infarction, sudden death and coronary insufficiency or suspected myocardial infarction; the relation was strongest with sudden death. Among men who had a myocardial infarction, body mass index was more strongly associated with sudden death and was the best predictor of myocardial infarction occurring after 20 years of observation. Thus, after adjustment for the effect of age and blood pressure, overweight is a definite risk factor but primarily in younger men, after long periods of observation and for certain manifestations of ischemic heart disease.

Relative role of factors associated with cerebral infarction and cerebral hemorrhage. A matched pair case-control study

Comprehensive ascertainment of all possible new cases of stroke appearing between January 1, 1970 and June 30, 1971, and admitted to three major hospitals in Winnipeg, Manitoba, has been achieved by reviewing the Manitoba Health Services Commission claim reports. The medical records of these cases were reviewed, pertinent data were abstracted, and rigid criteria for diagnosis were followed. Also, data were obtained from death certificates, autopsy reports and long-term hospital records. A total of 606 ascertained cases (410 infarction, 137 hemorrhage, and 59 undetermined type) were matched for age, sex, residence and year of admission with 606 controls from admissions for other than cardiovascular and cerebrovascular disorders. The data were analyzed for elucidating the possible risk factors for infarction (INF) and hemorrhage (HGE). The findings suggested that hypertension was the main risk factor in hemorrhage, whereas in infarction, along with hypertension, other factors such as diabetes, heart enlargement in chest x-ray, ECG abnormalities, and smoking were suggested as risk factors. There was an association also between infarction, on one hand, and the history of receiving anticoagulants, diuretics, and medications for the heart, and the occurrence of myocardial infarction, on the other hand. These features indicate that infarction and ischemic heart disease have similar risk factors. Hemoglobin and hematocrit were higher in infarction cases than in their controls only when measured at stroke admission. No difference was revealed when they were measured prior to stroke. Their association with infraction therefore may be secondary to other factors and of no significance for its risk.

Mathematical and mechanical modeling of stress-strain relationship of pericardium

Several mathematical expressions (models) were compared for use in describing the stress-strain (sigma - epsilon) relationship of pericardium. The expression sigma = alpha[ebeta epsilon - 1] was preferred because of its simpler form, theoretical consistency, and "good fit" of experimental data. A method was developed for estimating the precisions of the estimates of the parameters alpha and beta. This approach can have general usefulness in assessing the significance of a change in stress-strain relationship of various soft tissues following different interventions. A mechanical model was formulated for the pericardium which consisted of springs representing the collagen and elastin fibers connected in parallel. It could be simulated by the above equation and could describe the behavior of the pericardium.