Albinism in phylogenetically and geographically distinct populations of Astyanax cavefish arises through the same loss-of-function Oca2 allele

The Mexican tetra, Astyanax mexicanus, comprises 29 populations of cave-adapted fish distributed across a vast karst region in northeastern Mexico. These populations have a complex evolutionary history, having descended from 'old' and 'young' ancestral surface-dwelling stocks that invaded the region ∼6.7 and ∼2.8 MYa, respectively. This study investigates a set of captive, pigmented Astyanax cavefish collected from the Micos cave locality in 1970, in which albinism appeared over the past two decades. We combined novel coloration analyses, coding sequence comparisons and mRNA expression level studies to investigate the origin of albinism in captive-bred Micos cavefish. We discovered that albino Micos cavefish harbor two copies of a loss-of-function ocular and cutaneous albinism type II (Oca2) allele previously identified in the geographically distant Pachón cave population. This result suggests that phylogenetically young Micos cavefish and phylogenetically old Pachón cave fish inherited this Oca2 allele from the ancestral surface-dwelling taxon. This likely resulted from the presence of the loss-of-function Oca2 haplotype in the 'young' ancestral surface-dwelling stock that colonized the Micos cave and also introgressed into the ancient Pachón cave population. The appearance of albinism in captive Micos cavefish, caused by the same loss-of-function allele present in Pachón cavefish, implies that geographically and phylogenetically distinct cave populations can evolve the same troglomorphic phenotype from standing genetic variation present in the ancestral taxon.

Non-responders to previous treatment for hepatitis C

The main principle in treating chronic hepatitis C is the prevention of serious liver complications. Because curing hepatitis C virus infection has been demonstrated to prevent progression of liver disease and even promote regression of fibrosis, it remains the primary goal of treatment. However, nearly half of patients are not cured with our best treatment. Patients who failed older therapies should be treated with peginterferon and ribavirin, but those with advanced fibrosis or African heritage will have very low rates of response. Non-responders to peginterferon and ribavirin present a special challenge. If there were problems related to dosing, adherence, or access during treatment, then one can consider re-treating with the same regimen if the problems can be corrected. Otherwise, non-responders with early-stage fibrosis can observe without further treatment until newer drugs are available. Those with advanced fibrosis should consider low-dose peginterferon maintenance treatment or participation in an experimental trial. Experimental approaches include intensification of existing therapies, combination of new agents with existing drugs, long-term virus suppression, inhibition of liver fibrogenesis, and inhibition of hepatitis C RNA or hepatitis C viral enzymes.

Herpes esophagitis: clinical syndrome, endoscopic appearance, and diagnosis in 23 patients

The unexpected diagnosis of herpetic esophagitis in a patient with nausea led us to review our experience with this disease. Review of our records from 1979 to 1989 produced 23 cases proven by endoscopic culture or microscopic examination (Cowdry-type A inclusions), the largest such series reported to date. Twenty-two of the 23 patients were immunocompromised. Odynophagia and chest pain were each present in half of the cases, but 26% of patients had neither. Gastrointestinal bleeding was attributable to herpetic esophagitis in 30%. Thirty percent of patients had disseminated herpes simplex infection and 70% had simultaneous infections with other organisms. Endoscopic findings included nonspecific inflammation, discrete ulcers, coalescent ulcers, and pseudomembranous esophagitis. Herpes virus was not suspected endoscopically as the cause of esophagitis in 30% of cases. Culture was slightly more sensitive than microscopic examination for diagnosis (89% vs. 76%), but both methods should be employed in any immunocompromised patient with esophagitis.

Outcome of hospital care of liver disease associated with hepatitis C in the United States

We describe mortality and resource utilization for inpatient care of hepatitis C (HCV) in comparison to alcohol-induced liver disease (ALD) in the United States and identify factors that affect outcomes. The Healthcare Cost and Utilization Project database, a national inpatient sample was used to identify hospitalization records with diagnoses related to liver disease from HCV and ALD. Outcome of hospitalizations was analyzed in terms of in-hospital deaths and health care resource utilization. For 1995, we estimate that there were 26,700 hospitalizations and 2,600 deaths in acute, nonfederal hospitals in the United States for liver diseases caused by HCV. Total charges for these hospitalizations were $514 million. In comparison, ALD was associated with 101,200 hospitalizations, 13,400 deaths, and $1.8 billion in charges. Simultaneous HCV and alcohol abuse was associated with younger ages at the time of hospitalization and death compared with HCV or ALD alone. In a logistic regression analysis, alcohol abuse (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.2-1.5) and human immunodeficiency virus (HIV) infection (OR, 4.5; 95% CI, 4.0-4.9) were associated with an increased risk of death among those with HCV. Liver transplantation and patient death were associated with the largest increase in hospitalization charges. Major complications of cirrhosis, such as variceal bleeding, encephalopathy, and hepatorenal syndrome, and sociodemographic factors, such as race and health insurance, were also significantly associated with the risk of death and hospitalization charges, which were similar in HCV and ALD. This study provides new estimates regarding the public health impact of HCV, for use in health policy decisions and cost-effectiveness analyses of preventive and therapeutic interventions.

Human leukocyte antigen DR markers as predictors of progression to liver transplantation in patients with chronic hepatitis C

OBJECTIVE

Because many patients with chronic viral hepatitis do not progress to end-stage liver disease, it is possible that host factors such as human leukocyte antigen (HLA) differences are important. Our aims were to determine HLA marker-specific rates of progression to liver transplantation among patients with chronic hepatitis C; and to determine if polymerase chain reaction (PCR)-based HLA DRB1 typing can be performed on stored serum samples.

METHODS

Forty-two hepatitis C virus RNA-positive liver transplant patients and 87 untransplanted patients were included in a Cox proportional hazards model to test whether the occurrence of certain HLA DRB1 markers were associated with progression to liver transplantation. HLA DRB1 typing was performed on stored serum samples using a PCR method.

RESULTS

There were no differences among the HLA DRB1 markers with regard to the HLA marker-specific rate of progression to transplantation among patients with chronic hepatitis C.

CONCLUSIONS

HLA DRB1 markers do not appear to be associated with progression of disease in chronic viral hepatitis C. It is possible to perform PCR-based HLA DRB1 typing on stored frozen serum samples.

Multiport epidural catheters: does the air test work?

BACKGROUND

Multiport epidural catheters are popular; however, the reliability of the air test has not been evaluated with this catheter design. The authors determined the effectiveness of aspirating for blood and the air test in detecting intravascular multiorifice epidural catheters.

METHODS

Three hundred women in labor underwent placement of a blunt-tip, three-hole, 20-gauge, lumbar epidural catheter. If there were no signs of spinal anesthesia, 3 ml lidocaine or bupivacaine was injected and the patient was observed for signs of spinal anesthesia. If there were no signs of spinal anesthesia, the authors injected 1 ml air through the epidural catheter while listening to the maternal precordium using a Doppler fetal heart rate monitor. Catheters through which blood was aspirated were air-tested and replaced. Patients with air-test-positive, blood-aspiration-negative catheters received 100 mg lidocaine through the catheter and were questioned about toxicity symptoms. The authors injected bupivacaine-fentanyl through aspiration-negative,air-test-negative catheters and recorded the sensory analgesic level 20 min later.

RESULTS

The authors aspirated cerebrospinal fluid through one catheter and documented intravascular placement in 11 catheters. Results of the air test and blood aspiration were positive for eight catheters. Blood could not be aspirated from one air-test-positive catheter; perioral numbness developed in the patient after lidocaine injection. Blood was freely aspirated from two air-test-negative catheters. In the remaining 288 catheters, bupivacaine-fentanyl injection produced epidural analgesia in 279 patients and no effect in 9 patients.

CONCLUSIONS

The authors obtained false-negative results with both catheter aspiration and the air test. Fractionating the local anesthetic dose is important when using multiorifice epidural catheters.

Hepatitis A antibodies in liver transplant recipients: evidence for loss of immunity posttransplantation

Liver transplant recipients frequently have chronic liver diseases and should be considered for vaccination against hepatitis A virus (HAV). However, persistence of protective antibodies after orthotopic liver transplantation (OLT) has not been shown in this population, which may have implications for future vaccine recommendations. We evaluated the prevalence and epidemiological significance of immunoglobulin G (IgG) antibody to HAV (anti-HAV) in a nonvaccinated population before OLT (immunity from previous exposure) and determined the persistence of IgG anti-HAV at 1 and 2 years after OLT. One hundred consecutive patients were identified who underwent OLT and had at least 2 years of follow-up post-OLT. They were not vaccinated against HAV infection at any time. Clinical data were summarized from medical records, and stored sera were tested for IgG anti-HAV before OLT and at 1 and 2 years after OLT by a commercially available enzyme immunoassay. Of 100 patients, 24 had IgG anti-HAV before OLT. No epidemiological differences were noted between those with or without detectable IgG anti-HAV before OLT. Among patients with detectable IgG anti-HAV before OLT, 4 of 22 patients (18%) and 7 of 24 patients (29%) became negative for IgG anti-HAV at 1 and 2 years post-OLT, respectively. None of the patients with undetectable IgG anti-HAV before OLT became positive at any time. Most of our patients with end-stage liver disease had no serological evidence for immunity against HAV. A significant proportion of patients with detectable protective antibodies before OLT lost their antibodies at 2 years after OLT.

The pharmacodynamic effect of a remifentanil bolus on ventilatory control

BACKGROUND

In doses typically administered during conscious sedation, remifentanil may be associated with ventilatory depression. However, the time course of ventilatory depression after an initial dose of remifentanil has not been determined previously.

METHODS

In eight healthy volunteers, the authors determined the time course of the ventilatory response to carbon dioxide using the dual isohypercapnic technique. Subjects breathed via mask from a to-and-fro circuit with variable carbon dioxide absorption, allowing the authors to maintain end-tidal pressure of carbon dioxide (PET(CO2)) at approximately 46 or 56 mm Hg (alternate subjects). After 6 min of equilibration, subjects received 0.5 microg/kg remifentanil over 5 s, and minute ventilation (V(E)) was recorded during the next 20 min. Two hours later, the study was repeated using the other carbon dioxide tension (56 or 46 mm Hg). The V(E) data were used to construct two-point carbon dioxide response curves at 30-s intervals after remifentanil administration. Using published pharmacokinetic values for remifentanil and the method of collapsing hysteresis loops, the authors estimated the effect-site equilibration rate constant (k(eo)), the effect-site concentration producing 50% respiratory depression (EC50), and the shape parameter of the concentration-response curve (gamma).

RESULTS

The slope of the carbon dioxide response decreased from 0.99 [95% confidence limits 0.72 to 1.26] to a nadir of 0.27 l x min(-1) x mm Hg(-1) [-0.12 to 0.66] 2 min after remifentanil (P<0.001); within 5 min, it recovered to approximately 0.6 l x min(-1) x mm Hg(-1), and within 15 min of injection, slope returned to baseline. The computed ventilation at PET = 50 mm Hg (VE50) decreased from 12.9 [9.8 to 15.9] to 6.1 l/min [4.8 to 7.4] 2.5 min after remifentanil injection (P<0.001). This was caused primarily by a decrease in tidal volume rather than in respiratory rate. Estimated pharmacodynamic parameters based on computed mean values of VE50 included k(eo) = 0.24 min(-1) (T1/2 = 2.9 min), EC50 = 1.12 ng/ml, and gamma = 1.74.

CONCLUSIONS

After administration of 0.5 microg/kg remifentanil, there was a decrease in slope and downward shift of the carbon dioxide ventilatory response curve. This reached its nadir approximately 2.5 min after injection, consistent with the computed onset half-time of 2.9 min. The onset of respiratory depression appears to be somewhat slower than previously reported for the onset of remifentanil-induced electroencephalographic slowing. Recovery of ventilatory drive after a small dose essentially was complete within 15 min.

Unrecognized bulimia nervosa: a potential cause of perioperative cardiac dysrhythmias

PURPOSE

To report serious cardiac dysrhythmias in two patients whose bulimia nervosa was not revealed during preoperative screening.

CLINICAL REPORT

Case #1: A 25-yr-old woman with preoperative hypokalemia (K+ = 3.1 mEq x l(-1)) required anesthesia for removal of a wrist ganglion. She claimed the hypokalemia was of unknown etiology, and denied other medical problems. Shortly after induction of anesthesia with thiopental and isoflurane, the ECG revealed two runs of torsades de pointes. This was successfully treated by decreasing pulmonary ventilation, allowing P(ET)CO2 to increase from 32 to 45 mm Hg. Case #2: A 39-yr-old woman who denied any medical problems received propofol, rocuronium sevoflurane and N2O during general anesthesia for breast augmentation. In the PACU, the patient complained of light-headedness, and the ECG revealed a heart rate of 44 bpm with P-R interval of 0.42 sec. Following 0.5 mg atropine, the heart rate increased but the P-R interval remained prolonged (0.36 sec) and the corrected Q-T interval was 0.51 sec. Treatment with 2.5 g MgSO4, 20 mEq KCl, and 9.4 mEq calcium gluconate i.v. normalized the Q-T interval, and decreased the P-R interval to 0.22 sec. Upon specific questioning, she admitted to a remote history of bulimia, but denied any bulimic behavior for the last 16 yr.

CONCLUSION

Two patients with histories of eating disorders failed to disclose this information during preoperative evaluation. Perioperative cardiac dysrhythmias developed in these patients, even though they claimed that eating behavior had returned to normal.

Clinical significance of TT virus infection in patients with chronic hepatitis C

OBJECTIVE

The TT virus (TTV) is a novel DNA virus that has recently been identified. The clinical significance of TTV infection in patients with chronic hepatitis C has not been determined. The aim of this study was to determine the prevalence and possible role of TTV in a well characterized population with chronic hepatitis C infection.

METHODS

Ninety patients with chronic HCV and known time of HCV acquisition were selected from approximately 250 patients followed at our institution. Characteristics including age, sex, histology, and length of disease were recorded. Direct sequencing of the NS5 region was used for HCV genotyping. TTV DNA detection was based on PCR.

RESULTS

TTV infection was present in 24 of 90 (27%) HCV patients. Patients were divided into four groups based on stage of disease; chronic hepatitis (CH, 29 patients), compensated cirrhosis (CC, 17 patients), decompensated cirrhosis (DC, 28 patients), and hepatocellular carcinoma (HCC, 16 patients). TTV was present in 2/29 (7%), 2/17 (12%), 11/28 (39%), and 9/16 (56%) in those with CAH, CC, DC, and HCC respectively. TTV was significantly more prevalent among those with advanced disease (DC and HCC) compared to those with stable disease (CH and CC; p = 0.001). Mean age, sex, and the time from exposure to HCV to development of complications were similar in TTV-positive and -negative patients. TTV infection was more common in patients infected with HCV genotype 1b. Univariate analysis showed that length of HCV infection, HCV genotype 1b, and TTV infection were important in predicting the stage of liver disease in HCV patients. However, after adjusting for length of HCV infection, TTV but not HCV genotype was important in predicting the stage of liver disease.

CONCLUSIONS

We conclude that 1) TTV infection is common in patients with chronic HCV; 2) TTV infection is more prevalent among patients with advanced HCV-associated liver disease (DC and HCC) than in those with stable disease (CH and CC); and 3) TTV infection is more common in patients with HCV genotype 1b but is independent from genotype in predicting the stage of HCV-associated liver disease.

A comparison of midazolam and diazepam for conscious sedation during colonoscopy in a prospective double-blind study

BACKGROUND

Midazolam and diazepam are commonly used for conscious sedation, but their comparative respiratory depressive effects have not been accurately studied. We used a novel real-time, on-line, computerized data acquisition system to compare the two agents in a randomized double-blind study.

METHODS

One hundred patients undergoing colonoscopy were studied. The maximum end-tidal carbon dioxide tension (PetCO2) and the minimum oxygen saturation by pulse oximetry (SpO 2) were recorded by computer every minute. Patients received meperidine (25 to 50 mg) and incremental doses of either midazolam or diazepam to an identical end point of slurred speech and/or ptosis. Sedation was scored from 1 (unarousable) to 5 (wide awake).

RESULTS

Sedation scores were 3.6 +/- 0.1 (mean +/- standard error) after each agent. The doses of midazolam and diazepam were 0. 031 +/- 0.002 and 0.106 +/- 0.009 mg/kg, respectively. In the first 45 minutes (PetCO2) was significantly higher with midazolam than with diazepam (p < 0.05). SpO2 was significantly depressed for 80 minutes after each agent, and the number of minutes when the minimum Sp O2 was less than 90% did not differ between the two agents.

CONCLUSIONS

Midazolam was 3.4 times more potent than diazepam. The duration of oxygen desaturation emphasizes the importance of monitoring SpO2 until ventilation and oxygenation have recovered. Although the degree of hypoxemia was comparable, midazolam led to higher end-tidal carbon dioxide tensions.

The clinical significance of simultaneous infection with hepatitis G virus in patients with chronic hepatitis C

OBJECTIVES

Hepatitis G virus (HGV) is a recently discovered member of the flavivirus family that has been associated with acute and chronic hepatitis. HGV infection has been reported to coexist in 10-20% of patients with chronic hepatitis C. The significance of simultaneous infection with HGV and hepatitis C virus (HCV) remains to be clarified, as do the effects on HGV of therapeutic interventions such as interferon treatment or liver transplantation.

THE AIMS OF OUR STUDY WERE

1) to examine the frequency of HGV infection in the settings of liver transplantation and interferon therapy for hepatitis C; and 2) to compare HGV RNA levels before and after liver transplantation or interferon treatment.

METHODS

Pre-treatment sera were available in 65 patients with chronic hepatitis C treated with interferon; pretransplant sera were available in 49 patients transplanted for end stage liver disease associated with chronic hepatitis C. Information collected included age, sex, risk factors for hepatitis, concurrent liver disease, patient and allograft survival, biochemical response to interferon, histological activity index, and degree of fibrosis/cirrhosis. HCV genotyping was performed by sequencing the NS-5 region. HGV quantitation was performed using a research-based branched DNA (bDNA) assay with a set of probes directed at the 5' untranslated region.

RESULTS

HGV was detected in 10 of 49 patients (20%) before transplant and in 13 of 65 patients (20%) treated with interferon. There was a female predominance among HGV-positive compared with HGV-negative transplant patients (80% vs 20%; p < 0.01), but such a difference was not observed in the interferon-treated group. Hepatic iron concentration was lower in hepatic explants from patients who were HGV-positive than in those who were HGV-negative (318 +/- 145 microg/g dry weight vs 1497 +/- 2202 microg/g dry weight; p = 0.02). HCV exposure after 1980 was more common in the HGV-positive patients than in those who were HGV-negative for the entire study population (10 of 20 [50%] vs 16 of 66 [24%]; p = 0.03), as well as for the nontransplant subgroup (8 of 12 [67%] vs 12 of 39 [31%]; p = 0.03). HGV RNA levels declined at 1 yr after transplant in seven of eight patients. Among nine patients tested during or after interferon treatment, HGV RNA levels declined from pretreatment levels in all and disappeared in three.

CONCLUSIONS

Among patients with chronic hepatitis C treated with either interferon or liver transplantation, the frequency of coinfection with HGV is about 20%. HGV may be a more recent virus in the US than HCV. Coinfection with HGV does not appear to affect the likelihood of response to interferon in patients with hepatitis C. Finally, HGV RNA levels appear to decline after both liver transplantation and interferon therapy, suggesting possible suppression by increased HCV replication in the former case, and a possible drug treatment effect in the latter.

Diphenylhydramine increases ventilatory drive during alfentanil infusion

BACKGROUND

Diphenhydramine is used as an antipruritic and antiemetic in patients receiving opioids. Whether it might exacerbate opioid-induced ventilatory depression has not been determined.

METHODS

The ventilatory response to carbon dioxide during hyperoxia and the ventilatory response to hypoxia during hypercapnia (end-tidal pressure of carbon dioxide [PETCO2] is approximately equal to 54 mmHg) were determined in eight healthy volunteers. Ventilatory responses to carbon dioxide and hypoxia were calculated at baseline and during an alfentanil infusion (estimated blood levels approximately equal to 10 ng/ml) before and after diphenhydramine 0.7 mg/kg.

RESULTS

The slope of the ventilatory response to carbon dioxide decreased from 1.08+/-0.38 to 0.79+/-0.36 l x min(-1) x mmHg(-1) (x +/- SD, P < 0.05) during alfentanil infusion; after diphenhydramine, the slope increased to 1.17+/-0.28 l x min(-1) x mmHg(-1) (P < 0.05). The minute ventilation (VE) at PETCO2 approximately equal to 46 mmHg (VE46) decreased from 12.1+/-3.7 to 9.7+/-3.6 l/min (P < 0.05) and the VE at 54 mmHg (VE54) decreased from 21.3+/-4.8 to 16.6+/-4.7 l/min during alfentanil (P < 0.05). After diphenhydramine, (VE46 did not change significantly, remaining lower than baseline at 9.9+/-2.9 l/min (P < 0.05), whereas VE54 increased significantly to 20.5+/-3.0 l/min. During hypoxia, VE at SpO2 = 90% (VE90) decreased from 30.5+/-9.7 to 23.1+/-6.9 l/min during alfentanil (P < 0.05). After diphenhydramine, the increase in VE90 to 27.2+/-9.2 l/min was not significant (P = 0.06).

CONCLUSIONS

Diphenhydramine counteracts the alfentanil-induced decrease in the slope of the ventilatory response to carbon dioxide. However, at PETCO2 = 46 mmHg, it does not significantly alter the alfentanil-induced shift in the carbon dioxide response curve. In addition, diphenhydramine does not exacerbate the opioid-induced depression of the hypoxic ventilatory response during moderate hypercarbia.

Clinician's guide to hepatitis C

Hepatitis C virus infection is common, often silent, and almost always chronic and can lead to cirrhosis and hepatocellular cancer. Deaths related to chronic hepatitis C are expected to increase dramatically in the future. Many cases of infection are asymptomatic and are undiagnosed because of a lack of recognition by patients and physicians. All patients currently or previously at risk of infection should undergo screening, including those who received blood transfusions before 1992. Interferon is the only effective therapy, but disappearance of virus is sustained in only 10 to 15% of patients. The combination of interferon and oral ribavirin therapy may increase the sustained response rate to about 40%. New agents such as hepatitis C virus-specific protease inhibitors may be available in the next 5 to 10 years, and treatment is evolving toward multiple-drug regimens analogous to those used for human immunodeficiency virus (HIV) infection. In contrast to public funding for drug development in HIV, such funding for hepatitis C has been limited.

Treatment of chronic hepatitis C with interferon with or without ursodeoxycholic acid: a randomized prospective trial

The only effective and approved therapy for chronic hepatitis C is interferon-alpha. Because sustained response rates with interferon alone are disappointingly low, multidrug treatment regimens are currently being investigated. Ursodeoxycholic acid has been used in other chronic liver diseases and can limit hepatocyte injury. To evaluate the potential benefit of ursodeoxycholic acid in combination with interferon-alpha for the treatment of chronic hepatitis C, we conducted a prospective, double-blinded, randomized, placebo-controlled trial comparing the combination therapy of interferon-alpha 2b and ursodeoxycholic acid with interferon alone. Thirty-one patients with chronic hepatitis C were randomized to receive 3 million units of interferon-alpha 2b subcutaneously three times per week and either 13 to 15 mg/kg/day ursodeoxycholic acid or placebo orally for 6 months. The 6-month treatment period was followed by 6 months of observation. Biochemical normalization at the end of treatment occurred in 5 of 14 (36%) patients receiving monotherapy versus 8 of 15 (53%) patients (p = 0.34) receiving combination therapy. No patient treated with interferon alone had a sustained biochemical response 6 months after therapy; however, 3 of 12 patients (25%) treated with combination interferon and ursodeoxycholic acid maintained biochemical normalization at 6 months after therapy (p = 0.08). No difference in liver histology or clearance of hepatitis C viral RNA was noted 6 months after treatment. We conclude that combination therapy with ursodeoxycholic acid and interferon-alpha 2b was no more effective than interferon monotherapy in inducing a biochemical response in previously untreated patients with chronic hepatitis C. Ursodeoxycholic acid, however, may be useful in prolonging the biochemical response to interferon therapy.

Hepatitis G virus infection in patients transplanted for cryptogenic cirrhosis: red flag or red herring?

BACKGROUND

The significance of hepatitis G (HGV) infection in liver transplant recipients is not known. We set out to determine the pre-orthotopic liver transplantation (OLT) prevalence, the pre- and postoperative viral titers of HGV, and the allograft histology in patients infected with HGV who underwent OLT for cryptogenic cirrhosis.

METHODS

HGV RNA was measured using a research-based branched DNA assay. The assay used a target-specific probe set that was based on the 5'-untranslated region of the HGV genome. Allograft histology was assessed with protocol liver biopsies in all patients who survived longer than 6 months.

RESULTS

The preoperative prevalence of HGV infection in recipients transplanted for cryptogenic cirrhosis was 26%. Thirty-seven percent (12 of 33) of recipients who had serum available in the first postoperative month had HGV infection. Mean HGV RNA levels were 9.8 (+/-4.2) (viral molecular equivalents/ml x 10[6]) before OLT and 37.5 (+/-10.7) at 1 year after OLT. In 4 of the 11 cryptogenic recipients in whom HGV RNA was detectable in the first postoperative month, HGV RNA fell to undetectable levels at the most recent follow-up (mean 70 months). Of the five cryptogenic recipients who continue to have measurable HGV RNA, three have unexplained hepatitis histologically.

CONCLUSIONS

These findings suggest the following: 1) The prevalence of HGV infection in patients undergoing OLT for cryptogenic cirrhosis is about 25%. 2) In recipients persistently infected with HGV, mean HGV RNA titers increase after OLT. 3) HGV RNA becomes undetectable in about one third of recipients who had detectable HGV RNA in the first month after OLT. 4) Hepatitis of uncertain etiology occurs in 60% (3 of 5) of persistently HGV-infected cryptogenic recipients.

Cost-effectiveness of 6 and 12 months of interferon-alpha therapy for chronic hepatitis C

BACKGROUND

Interferon-alpha is effective in only a small number of patients with chronic hepatitis C, although prolonged treatment may increase the response rate. There is concern that the expense of interferon-alpha therapy may not be justified by the low response rates and uncertain long-term benefit.

OBJECTIVE

To compare clinical and economic outcomes after 6 months and 12 months of interferon-alpha therapy for chronic hepatitis C.

DESIGN

A Markov model depicting the natural progression of chronic hepatitis C. On the basis of this model, a simulated trial compared no therapy with 6 and 12 months of interferon-alpha therapy at standard doses (3 million U three times weekly).

PATIENTS

Four age-specific cohorts (30, 40, 50, and 60 years of age) with chronic hepatitis C.

MEASUREMENTS

Number of deaths from liver disease, total costs, and cumulative quality-adjusted life-years (QALYs).

RESULTS

Six and 12 months of interferon-alpha treatment gained 0.25 QALYs at an incremental cost of $1000 and 0.37 QALYs at an incremental cost of $1900, respectively. Thus, although 6 months of interferon-alpha therapy was less efficacious than 12 months of therapy, it was more cost-effective ($4000 per QALY gained compared with $5000 per QALY gained). Nonetheless, in patients younger than 60 years of age, both 6 and 12 months of therapy compared favorably with other established medical interventions, such as screening mammography and cholesterol reduction programs. Important variables affecting the cost-effectiveness of interferon-alpha treatment included the cost and efficacy of interferon-alpha, the cost of treatment for decompensated cirrhosis, and quality of life in patients with chronic hepatitis C.

CONCLUSION

From the standpoint of cost-effectiveness, interferon-alpha therapy for 6 or 12 months may be justified in patients with chronic hepatitis C. The possible exception is patients older than 60 years of age.

Chronic alcohol abuse and the acute sedative and neurophysiologic effects of midazolam

The aim of the present investigation was to examine benzodiazepine sensitivity in abstinent alcoholics. For this purpose, two escalating doses of the benzodiazepine midazolam were i.v. administered to nine alcohol-dependent patients after 2-3 weeks of abstinence and 12 healthy, non-alcoholic volunteers. A variety of dependent measures were examined, including the power spectrum of the resting electroencephalogram (EEG) and evoked EEG responses, saccadic eye movements, self-reported sedation, and vigilance task performance. Analyses revealed a significant association between plasma midazolam levels and changes in EEG beta power, pattern shift visual evoked potential amplitude, heart rate, and saccade amplitude and velocity. The patient and control groups differed significantly in the onset latencies of their saccadic eye movements, and marginally in EEG beta power, both before and after midazolam. However, no differences were detected between the groups in the dose of midazolam required to produce sedation or in midazolam's neurophysiological effects.

Relationship between hepatitis C genotype and severity of recurrent hepatitis C after liver transplantation

BACKGROUND

Recurrence of hepatitis C virus (HCV) infection after liver transplantation is universal, but the relationship between hepatitis C genotype and posttransplant outcome has been controversial. The aim of this study was to assess the relationship between hepatitis C genotype on posttransplant frequency of recurrent hepatitis, histologic severity of recurrence, and progression to cirrhosis.

METHODS

We studied 42 HCV RNA positive patients who received transplants between 1985 and 1994. Sera were tested for HCV RNA and protocol liver biopsies were in obtained the posttransplant period. Biopsies were scored according to the histologic activity index (HAI) and staged in a blinded fashion.

RESULTS

The distribution of hepatitis C genotypes distribution was as follows: 1a, 19 (45%); 1b, 17 (40%); 2b, 3 (7%); and 1 each of 2a, 3a, and 4a. There was histologic evidence of hepatitis in 38 of 42 (90.4%) of patients. Hepatitis C was mild, moderate, or severe (HAI>3) in 38% of grafts and minimal (HAI 0-3) in 62%. Overall HAI scores and histologic stage were higher in the genotype 1b group. Six of 17 (35%) genotype 1b patients had cirrhosis compared with 2 of 25 (8%) in the non-1b genotype group.

CONCLUSIONS

(1) Histologic evidence of recurrent hepatitis C is seen in 90% of liver allografts; (2) Histologic hepatitis C recurs with similar frequency in genotype 1b and non-1b recipients; (3) Genotype 1b is associated with more severe histologic disease recurrence than non-1b genotypes; (4) Genotype 1b appears to be associated with a higher degree of posttransplant fibrosis and cirrhosis than non-1b genotypes.

Increased risk of hepatocellular carcinoma in patients infected with hepatitis C genotype 1b

Infection with hepatitis C virus (HCV) genotype 1b has been reported to be associated with more severe liver disease and an unfavorable outcome. Liver transplantation allows for a complete examination of the explanted liver for the detection of hepatocellular carcinoma (HCC).

OBJECTIVE

To study the prevalence of HCC in patients with liver cirrhosis secondary to chronic infection with HCV genotype 1b compared with those infected with other genotypes.

METHODS

Sera were collected from 48 consecutive patients undergoing liver transplantation for end stage liver disease secondary to HCV infection. RNA was extracted from serum using chaotropic lysis and isopropanol precipitation. Reverse transcriptase-polymerase chain reaction of the NS5 region was performed, followed by automated sequencing on desalted amplification products. Genotype assignment followed Simmonds's classification. All explanted livers were examined for the presence of HCC.

RESULTS

HCV genotypes in our patients were as follows: subtype 1a, 20 patients (42%); 1b, 18 patients (37.5%); 2a, one patient (2%); 2b, six patients (12.5%); 3a, one patient (2%); and 4a, two patients (4%). Although five of 18 patients infected with HCV genotype 1b (28%) had HCC, only one of 30 patients (3%) infected with all other genotypes (1a, 2a, 2b, 3a, and 4a) had HCC (p = 0.02).

CONCLUSION

Infection with HCV genotype 1b may carry a higher risk for the development of HCC than infection with other HCV genotypes.

Effect of flumazenil on ventilatory drive during sedation with midazolam and alfentanil

BACKGROUND

Patients who receive a combination of a benzodiazepine and an opioid for conscious sedation are at risk for developing respiratory depression. While flumazenil effectively antagonizes the respiratory depression associated with a benzodiazepine alone, its efficacy in the presence of both a benzodiazepine and an opioid has not been established. This study was designed to determine whether flumazenil can reverse benzodiazepine-induced depression of ventilatory drive in the presence of an opioid.

METHODS

Twelve healthy volunteers completed this randomized, double-blind, crossover study. Ventilatory responses to carbon dioxide and to isocapnic hypoxia were determined during four treatment phases: (1) baseline, (2) alfentanil infusion; (3) combined midazolam and alfentanil infusions, and (4) combined alfentanil, midazolam, and "study drug" (consisting of either flumazenil or flumazenil vehicle) infusions. Subjects returned 2-6 weeks later to receive the alternate study drug.

RESULTS

Alfentanil decreased the slope of the carbon dioxide response curve from 2.14 +/- 0.40 to 1.43 +/- 0.19 l.min-1.mmHg-1 (x +/- SE, P < 0.05), and decreased the minute ventilation at P(ET)CO2 = 50 mmHg (VE50) from 19.7 +/- 1.2 to 14.8 +/- 0.9l.min-1 (P < 0.05). Midazolam further reduced these variables to 0.87 +/- 0.17 l.min-1.mmHg-1 (P < 0.05) and 11.7 +/- 0.8 l.min-1 (P < 0.05), respectively. With addition of flumazenil, slope and VE50 increased to 1.47 +/- 0.37 l.min-1.mmHg-1 (P < 0.05) and 16.4 +/- 2.0l.min-1 (P < 0.05); after placebo, the respective values of 1.02 +/- 0.19 l.min-1.mmHg-1 and 12.5 +/- 1.2 l.min-1 did not differe significantly from their values during combined alfentanil and midazolam administration. The effect of flumazenil differed significantly from that of placebo (P < 0.05). Both the slope and the displacement of the hypoxic ventilatory response, measured at P(ET)CO2 = 46 +/- 1 mmHG, were affected similarly, with flumazenil showing a significant improvement compared to placebo.

CONCLUSIONS

Flumazenil effectively reverses the benzodiazepine component of ventilatory depression during combined administration of a benzodiazepine and an opioid.

The role of ultrasonography and automatic-needle biopsy in outpatient percutaneous liver biopsy

The risk of complications from percutaneous liver biopsy is low, but discomfort is common and complications require hospitalization in approximately 4% of patients. The optimal method of performing these biopsies is unknown. The goal of our study was to determine whether the use of ultrasonography in the biopsy room immediately prior to or during the procedure would lessen the risk of complications and to compare the safety and efficacy in obtaining tissue by use of a Trucut needle versus an automatic biopsy needle. Between 1992 and 1994, 836 patients were entered into a randomized study (489 in Rochester, MN; 347 in Barcelona, Spain). Patients were randomized immediately prior to liver biopsy into four groups: Trucut needle, or automatic biopsy needle, and with or without ultrasonography. Fisher's Exact Test and a logistic regression model were also used to assess the effect of needle and ultrasonography on the odds for complications. The four biopsy groups were well-matched at entry with respect to age, sex, underlying liver disease, hemoglobin, prothrombin time, and platelet count. The use of ultrasound was associated with a decreased rate of hospitalization for pain, hypotension, or bleeding (2 vs. 9, P < .05). No difference in safety was found between the two types of needles. The number of passes needed to obtain specimens was similar for all four groups. The average length of the specimen was slightly greater with ultrasonographic-guided biopsies (1.7 mm vs. 1.6 mm, P < .05) and with biopsies obtained using the automatic biopsy needle when compared with the Trucut needle (1.7 mm vs. 1.5 mm, P < .05), but this did not seem to be clinically important. The addition of ultrasonography reduces complications in patients undergoing percutaneous liver biopsy. The type of needle appears to offer little difference in safety or yield of diagnostic tissue. The use of ultrasonography for guidance of percutaneous liver biopsy will lead to a lower rate of complications. The value of this benefit must be weighed against the added cost of ultrasonographic guidance.

The role of ultrasonography and automatic-needle biopsy in outpatient percutaneous liver biopsy

The risk of complications from percutaneous liver biopsy is low, but discomfort is common and complications require hospitalization in approximately 4% of patients. The optimal method of performing these biopsies is unknown. The goal of our study was to determine whether the use of ultrasonography in the biopsy room immediately prior to or during the procedure would lessen the risk of complications and to compare the safety and efficacy in obtaining tissue by use of a Trucut needle versus an automatic biopsy needle. Between 1992 and 1994, 836 patients were entered into a randomized study (489 in Rochester, MN; 347 in Barcelona, Spain). Patients were randomized immediately prior to liver biopsy into four groups: Trucut needle, or automatic biopsy needle, and with or without ultrasonography. Fisher's Exact Test and a logistic regression model were also used to assess the effect of needle and ultrasonography on the odds for complications. The four biopsy groups were well-matched at entry with respect to age, sex, underlying liver disease, hemoglobin, prothrombin time, and platelet count. The use of ultrasound was associated with a decreased rate of hospitalization for pain, hypotension, or bleeding (2 vs. 9, P < .05). No difference in safety was found between the two types of needles. The number of passes needed to obtain specimens was similar for all four groups. The average length of the specimen was slightly greater with ultrasonographic-guided biopsies (1.7 mm vs. 1.6 mm, P < .05) and with biopsies obtained using the automatic biopsy needle when compared with the Trucut needle (1.7 mm vs. 1.5 mm, P < .05), but this did not seem to be clinically important. The addition of ultrasonography reduces complications in patients undergoing percutaneous liver biopsy. The type of needle appears to offer little difference in safety or yield of diagnostic tissue. The use of ultrasonography for guidance of percutaneous liver biopsy will lead to a lower rate of complications. The value of this benefit must be weighed against the added cost of ultrasonographic guidance.

Sevoflurane versus isoflurane: induction and recovery characteristics with single-breath inhaled inductions of anesthesia

Because of its nonpungent odor and low blood-gas solubility coefficient, sevoflurane might be an ideal drug for single-breath inhaled induction of anesthesia. Fifty ASA grade I-III ambulatory surgical patients (18-76 yr old) received a single-breath induction with either 5.0% sevoflurane or 5.0% isoflurane (randomized) in a 1:1 N2O/O2 mixture. Anesthesia was maintained with the same anesthetic in 70% N2O until the end of surgery, when anesthetics were abruptly discontinued. Induction times (loss of eyelash reflex) were similar for sevoflurane (75 +/- 3 s, mean +/- se) and isoflurane (67 +/- 4 s, P = not significant). Sevoflurane patients were less likely to have complications during induction (P < 0.005); coughing occurred more frequently with isoflurane (P < 0.001). During induction, heart rate increased with both sevoflurane (from 73 +/- 3 to 90 +/- 4 bpm, P < 0.05) and isoflurane (from 70 +/- 2 to 92 +/- 2 bpm, P < 0.05); the increase with isoflurane was greater than that with sevoflurane. Times to eye opening for sevoflurane (8.1 1 +/- 1.0 min) did not differ significantly from those for isoflurane (10.6 +/- 1.3 min). Patients opened their eyes at lower end-tidal minimum alveolar anesthetic concentration (MAC)-fractions of sevoflurane (0.12 +/- 0.01 MAC) than isoflurane (0.15 +/- 0.01 MAC, P < 0.01). During recovery, patients who received sevoflurane felt less clumsy (P < 0.001) and less confused (P < 0.005) but had higher pain scores (P < 0.005) than those who received isoflurane. Sevoflurane is more suitable than isoflurane for single-breath induction, because it produces a smoother induction with a lower incidence of complications and better patient acceptance.

Liver resection and cyst fenestration in the treatment of severe polycystic liver disease

BACKGROUND/AIMS

There is limited information on treatment options for massive, highly symptomatic polycystic liver disease. The aim of the study was to analyze the immediate and long-term outcome of combined liver resection and fenestration.

METHODS

Information was abstracted from medical records. Follow-up was obtained by mailed questionnaire. Liver volume was quantified by computed tomography.

RESULTS

Thirty-one patients underwent liver resection and fenestration between July 1985 and June 1993. Mean liver volume was 9357 mL before and 3567 mL after surgery. There was one death from postoperative intracerebral bleed. Eighteen patients experienced complications, usually transient pleural effusions or transient ascites. Twenty-eight of 29 surviving patients with adequate follow-up have experienced immediate and sustained relief of symptoms and improvement in quality of life. After median follow-up of 2.4 years (range, 0.2 to 7.9 years), most patients have not had clinically significant enlargement of the liver. Sequential computed tomography scans before and after surgery suggest that hepatic enlargement in the age range of the patients in the study mainly resulted from the expansion of existing cysts rather than from the development of new cysts.

CONCLUSIONS

Selected patients with severe symptomatic polycystic liver disease and favorable anatomy benefit from liver resection and fenestration with acceptable morbidity and mortality. The extent of hepatic resection and fenestration is important for the long-term effectiveness of this procedure.

Hepatic venous outflow obstruction in autosomal dominant polycystic kidney disease

To discuss the clinical presentation, diagnosis, and treatment of hepatic venous outflow obstruction as a complication of polycystic liver disease, four cases diagnosed and treated at our institution have been reviewed and the information from six previously published case reports has been summarized. Eight of the 10 patients were women. All presented with severe ascites. Nine had polycystic kidneys. Three had moderate-to-advanced renal insufficiency, four were on hemodialysis, and one had a renal allograft. Possible predisposing factors were identified in seven patients; the most common was recent abdominal surgery, which, in three cases, was a bilateral nephrectomy. All patients had extrinsic compression of the hepatic veins and the inferior vena cava by hepatic cysts, and four had proven superimposed thrombosis of the inferior vena cava and/or hepatic veins. In the patients seen in this institution, magnetic resonance imaging was helpful in determining the level of obstruction in the inferior vena cava and the patency of the hepatic and portal veins. The outcome was worse in the patients with thrombosis; one recovered after a portocaval shunt, and the remaining three patients died. On the other hand, five of the six patients without thrombosis recovered after alcohol sclerosis of a large dominant cyst (one patient) or after hepatic resection and cyst fenestration (four patients). Hepatic venous outflow obstruction probably has been underrecognized as a cause of portal hypertension, ascites, and liver dysfunction in polycystic liver disease. The diagnosis can be reliably established with current imaging techniques, especially magnetic resonance imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Diphenhydramine enhances the interaction of hypercapnic and hypoxic ventilatory drive

BACKGROUND

Although diphenhydramine is frequently used to treat pruritus and nausea in patients who have received neuraxial opioids, there are no data regarding its effect on ventilatory control. We conducted the current study to evaluate the effects of diphenhydramine on hypercapnic and hypoxic ventilatory control in healthy volunteers.

METHODS

First, we measured the steady-state ventilatory response to carbon dioxide during hyperoxia with an end-tidal carbon dioxide tension of 46 or 54 mmHg (alternate subjects) in eight healthy volunteers. We then determined the hypoxic ventilatory response during isocapnic rebreathing at the same carbon dioxide tension. After a 10-min recovery period, we repeated the steady-state and hypoxic ventilatory response measurements at the other carbon dioxide tension (54 or 46 mmHg). Ten minutes after subjects received diphenhydramine 0.7 mg.kg-1 intravenously, we repeated this sequence of ventilatory measurements.

RESULTS

Under hyperoxic conditions (inspired oxygen fraction > 0.5) diphenhydramine did not affect the ventilatory response to hypercapnia. Similarly, at an end-tidal carbon dioxide tension of 46 mmHg, neither the slope nor the position of the hypoxic ventilatory response curve changed significantly after diphenhydramine. However, at an end-tidal carbon dioxide tension of 54 mmHg, the slope of the hypoxic ventilatory response increased from 1.28 +/- 0.33 to 2.13 +/- 0.61 l.min-1.%SpO2(-1) (mean +/- standard error), and VE at an arterial hemoglobin oxygen saturation of 90% increased from 31.2 +/- 3.1 to 43.1 +/- 5.4 l.min-1).

CONCLUSIONS

We conclude that although it did not affect the ventilatory response to carbon dioxide during hyperoxia or the ventilatory response to hypoxia at an end-tidal carbon dioxide tension of 46 mmHg diphenhydramine augmented the hypoxic response under conditions of hypercapnia in our young healthy volunteers. Although these findings may help to explain the apparent safety of diphenhydramine, they may not be applicable to debilitated patients or those who have received systemic or neuraxial ventilatory depressants.

Propofol depresses the hypoxic ventilatory response during conscious sedation and isohypercapnia

BACKGROUND

Propofol infusion at subanesthetic doses provides reliable conscious sedation. However, the ventilatory effects of sedative doses of propofol have not been established. The current study was conducted to determine the effects of propofol sedation on the hypoxic ventilatory response.

METHODS

Eight healthy, male volunteers received 1 mg.kg-1 propofol followed by a propofol infusion adjusted to maintain a constant, subanesthetic level of sedation. Hypoxic ventilatory response was measured using an isocapnic rebreathing technique: while keeping PETCO2 constant (approximately 6 mmHg above prestudy baseline), the authors continuously recorded minute ventilation and tidal volume, as oxygen saturation (SpO2) decreased from 98 to 70%. Hypoxic response determinations were performed before and during propofol infusion, as well as 30 and 60 min after termination of the propofol infusion.

RESULTS

The slope of the hypoxic ventilatory response curve (VE vs. SpO2) decreased from 0.88 +/- 0.15 to 0.17 +/- 0.03 l.min-1.%SpO2 -1 during propofol sedation (mean +/- SE). Thirty minutes after discontinuation of the propofol infusion, slope returned to its prepropofol value. In addition, minute ventilation at SpO2 = 90% decreased during propofol sedation, from 16.1 +/- 0.8 to 8.7 +/- 0.4 l.min-1, accompanied by a similar decrease in tidal volume at SpO2 = 90%, from 1,099 +/- 87 to 523 +/- 21 ml. Thirty minutes after discontinuation of the propofol infusion, these variables also returned to their prepropofol values.

CONCLUSIONS

The authors concluded that propofol infusion for conscious sedation significantly decreases the slope and causes a downward shift of the hypoxic ventilatory response curve measured during isohypercapnia.

Prevalence of peritonitis and the ascitic fluid protein concentration among chronic liver disease patients

The prevalence of spontaneous bacterial peritonitis (SBP) or its variants, bacterascites (BA), and culture-negative neutrocytic ascites (CNNA), may vary depending on the underlying liver disease and protein content of ascites. In this study, we compared the frequency of peritonitis (SBP, BA, CNNA) upon admission in alcoholic (ALD), cholestatic (CLD), and hepatocellular liver disease (HLD); determined the relationship between Child's class and prevalence of peritonitis; and assessed ascitic total protein as a risk factor for peritonitis. Between January 1989 and April 1991, 113 consecutive patients were admitted with chronic liver disease and ascites (49, ALD; 22, CLD; and 42, HLD). All had admission paracentesis. SBP was defined as polymorphonuclear cell count (PMN) > or = 250 mm3 with a positive culture, BA as PMN < 250/mm3 and positive culture, and CNNA as PMN > or = 250/mm3 with negative culture. No patients with obvious intraabdominal source for infection (i.e., secondary peritonitis) were included in the analysis. The prevalence of peritonitis was 8/113 (7%); four patients had SBP, one BA, and three CNNA. The occurrence of peritonitis was independent of the type of liver disease (ALD, 8%; CLD, 9%; HDL, 5%). Neither ascitic fluid total protein nor the severity of liver disease (Child's class) predicted the occurrence of peritonitis. We conclude that the occurrence of peritonitis is unrelated to the type of liver disease, and severity of liver disease did not predict the presence of peritonitis. Also, ascitic fluid total protein < 1.0 g/dl may not be a sensitive predictor of risk of peritonitis.

Nerve stimulator polarity and brachial plexus block

To determine whether needle polarity significantly affects nerve stimulation during peripheral nerve block, we performed a randomized double-blinded study of 10 patients undergoing axillary block for upper extremity surgery. Using an insulated needle, we determined the minimum current necessary to elicit muscle contraction with positive and negative needle polarity at two needle placements: (A) where stimulation was first observed and (B) where stimulation was maximal. At Position A, stimulation required significantly more current when the needle was positive (2.32 +/- 0.45 mA, mean +/- SEM) than when it was negative (1.05 +/- 0.23 mA, P < 0.001). Similarly, at Position B, stimulation required more current when the needle was positive (1.49 +/- 0.49 mA) than when it was negative (0.47 +/- 0.15 mA, P < 0.001). The mean ratio of positive to negative threshold stimulation current at Position B (3.11 +/- 0.20) was significantly greater than that at Position A (2.37 +/- 0.19, P < 0.05). Our results emphasize the importance of attaching the negative terminal of the nerve stimulator to the stimulating electrode. Use of the positive terminal could lead to abandoning a block if stimulation were not obtained at a low enough current; alternatively, motor contraction might not be observed before neural contact or vascular puncture.

High-volume postobstructive choleresis after transhepatic external biliary drainage resolves with conversion to internal drainage

We report high-volume postobstructive choleresis in two patients who underwent transhepatic external drainage for malignant biliary obstruction. Excessive loss of bicarbonate-rich biliary fluid (up to 6.5 L/day) caused orthostatic hypotension, prerenal insufficiency, hyponatremia, and a decrease in serum bicarbonate. Therapy with isotonic fluids containing sodium, chloride, lactate, bicarbonate, and potassium was based on measurement of biliary fluid volume and electrolyte concentrations. Biliary fluid loss was terminated by conversion to internal biliary drainage. The reason for this rare complication of external drainage of biliary obstruction is unknown, but such patients must be closely monitored for volume loss. When high-volume choleresis occurs, biliary fluid and electrolyte losses should be precisely measured and replaced, and external biliary drainage converted to internal drainage.

Sedative doses of propofol increase beta activity of the processed electroencephalogram

The effects of sedative infusions of propofol on the processed electroencephalograms (EEG) of eight healthy male volunteers were studied. EEG data for aperiodic analysis were collected during three 5-min periods: before propofol, during propofol infusion, and 30 min after termination of the infusion. After an initial dose of 1 mg/kg, subjects received a propofol infusion titrated to produce a standard level of conscious sedation. The infusion rate was 84 +/- 27 micrograms.kg-1 x min-1 (mean +/- SE) and plasma propofol levels were 2180 +/- 43 ng/mL. Total EEG power, defined as the sum of the squares of peak-to-peak amplitudes during each 5-s epoch, increased from 1350 +/- 295 microV2 x epoch-1 to 9675 +/- 2390 microV2 x epoch-1 during the propofol infusion (P < 0.05); it returned to 1445 +/- 145 microV2 x epoch-1 30 min after the infusion was discontinued (P < 0.05 vs the result during propofol). The change in total power was accompanied by a change in the distribution of power within the EEG spectrum, as the fraction of activity in the beta-band (12-35 Hz) increased during the infusion from 23% +/- 3% to 44% +/- 5% (P < 0.05). Thirty minutes after the infusion was terminated, the distribution of activity within the EEG spectrum had reverted to pre-propofol patterns. The similarity of EEG effects seen with sedative doses of propofol and benzodiazepines suggests that these drugs may share some neurochemical effects.

Randomized controlled trial of recombinant alpha-2a-interferon for chronic hepatitis C. Comparison of alanine aminotransferase normalization versus loss of HCV RNA and anti-HCV IgM

We enrolled 32 patients with chronic hepatitis C into a randomized, controlled trial to evaluate the efficacy of recombinant alpha-2a-interferon treatment. Sixteen patients were randomized to receive 1.5 million units of recombinant alpha-2a-interferon subcutaneously, thrice weekly, for six months while the remaining 16 patients were randomized to a control group that received no treatment. The mean serum alanine aminotransferase (ALT) level during the six-month study period, expressed as a percentage of the prestudy baseline value, was 82% for the control group compared to 56% for the treatment group (P = 0.014). One fourth of the treatment group normalized their serum ALT level compared to only 6% of the controls (P = 0.05). During posttherapy follow-up, 86% of responders clinically relapsed. Loss of anti-HCV IgM and HCV RNA occurred exclusively in interferon-treated responders. Anti-interferon antibodies developed in 32% of all treated patients. Forty percent of nonresponders developed anti-interferon antibodies compared to only 14% of responders (P = NS). We conclude that recombinant alpha-2a-interferon is clinically effective in patients with chronic hepatitis C. However, most responders in this trial of low-dose interferon relapsed upon cessation of treatment.

The effect of flumazenil on midazolam-induced depression of the ventilatory response to hypoxia during isohypercarbia

BACKGROUND

While flumazenil reverses benzodiazepine-induced sedation, its ability to antagonize the ventilatory depressant effects of benzodiazepines has not been fully established. A randomized, double-blind study was conducted to determine whether flumazenil effectively reverses midazolam-induced depression of the hypoxic ventilatory response.

METHODS

Twelve healthy male volunteers received intravenous midazolam 0.12 +/- 0.01 mg.kg-1 followed by either flumazenil 1.0 mg or placebo. Hypoxic ventilatory response was measured using an isocapnic rebreathing technique: as Spo2 decreased to 70% VE and tidal volume were continuously recorded. Hypoxic response determinations were performed before and after midazolam, as well as 3, 30, 60, 120, and 180 min after flumazenil or placebo.

RESULTS

After midazolam, the slope of the hypoxic ventilatory response curve (VE vs. SpO2) decreased to 0.59 +/- 0.05 (means +/- SE) times its premidazolam baseline; likewise, at Spo2 = 90%, minute ventilation (VE90) and tidal volume (TV90) decreased to 0.70 +/- 0.04 and 0.62 +/- 0.03 times baseline, respectively. Three minutes after flumazenil, the slope increased to 1.10 +/- 0.13 times baseline (P < 0.05 vs. postmidazolam), while following placebo, it was only 0.81 +/- 0.09 times baseline (P = NS vs. postmidazolam, P < 0.05 between treatments). VE90 and TV90, after flumazenil, increased to 1.45 +/- 0.15 and 1.27 +/- 0.09 times baseline, respectively (P < 0.05 vs. postmidazolam); these increases were significantly greater than the corresponding changes observed after placebo (P < 0.05 between treatments).

CONCLUSIONS

It was concluded that, after sedation with midazolam, flumazenil causes a greater increase in hypoxic ventilatory response during isohypercarbic conditions than does placebo, and may, therefore, be useful in the treatment of midazolam-induced ventilatory depression.