Rapid magnetic cell delivery for large tubular bioengineered constructs.

Delivery of cells into tubular tissue constructs with large diameters poses significant spatial and temporal challenges. This study describes preliminary findings for a novel process for rapid and uniform seeding of cells onto the luminal surface of large tubular constructs. Fibroblasts, tagged with superparamagnetic iron oxide nanoparticles (SPION), were directed onto the luminal surface of tubular constructs by a magnetic field generated by a k4-type Halbach cylinder device. The spatial distribution of attached cells, as measured by the mean number of cells, was compared with a conventional, dynamic, rotational cell-delivery technique. Cell loading onto the constructs was measured by microscopy and magnetic resonance imaging. The different seeding techniques employed had a significant effect on the spatial distribution of the cells (p < 0.0001). The number of attached cells at defined positions within the same construct was significantly different for the dynamic rotation technique (p < 0.05). In contrast, no significant differences in the number of cells attached to the luminal surface were found between the defined positions on the construct loaded with the Halbach cylinder. The technique described overcomes limitations associated with existing cell-delivery techniques and is amenable to a variety of tubular organs where rapid loading and uniform distribution of cells for therapeutic applications are required.

A facile method for coding and labeling assays on polystyrene beads with differently colored luminescent nanocrystals.

The present paper describes a new, facile and fast technique that can be used to incorporate CdSe/ZnS core/shell nanocrystals into polystyrene beads. The nanocrystals were immobilized within the polymer beads by demixing two nonmiscible solvents. The resulting beads were bright, homogeneously coded, and did not show any surface texture or photobleaching under application-relevant conditions. The beads were subsequently used on a model streptavidin-biotin binding system in order to demonstrate the applicability of the technique to enzyme-linked assays and multiplexing applications.

Excitation dependence of steady-state photoluminescence in CdSe nanocrystal films.

The excitonic and deep-level photoluminescence (PL) in CdSe nanocrystal (NC) films (wurtzite type) was studied under continuous-wave excitation as a function of excitation power, temperature, and time of photoaging. It was shown that the intensity-power dependencies are identical for excitonic and deep-level emissions in a wide temperature range. At low temperatures (80-100 K), both emissions were saturated at the laser power used, which generates more than one exciton per nanocrystal. A transition point from the linear to the saturated region was dependent on the temperature, size, and quality of the NCs. A clear inverse dependency between the intensities of excitonic and deep-level emissions was revealed at 80 K over the entire sample area. At room-temperature, the quantum yield dropped significantly and a higher laser power was needed to reach PL saturation. An increase in temperature led to worsening of the reverse dependence between excitonic and deep-level emissions, and at room-temperature, they became uncorrelated. These results can be explained by Auger recombination and also by an increase of nonradiative recombination in the surface states with increasing temperature.

Light adaptation: night vision goggle effect on cockpit instrument reading time.

BACKGROUND: Light adaptation to the intensified image provided by a night vision device may handicap pilots who have set cockpit instrument luminance too low. METHODS: Under conditions simulating night flying, subjects adapted to an NVG image at 3 or 10 footlamberts (fL), then used a joystick to indicate the position of the horizon in an ADI illuminated by NVIS-compatible light at luminances 2 to 3.5 log units lower than the NVG image. RESULTS: Response times increased no more than a few tenths of a second when the decrease in luminance was only 2 log units. Greater decreases produced correspondingly longer delays in response, reaching as much as 5.5 s for subjects in their twenties and 8-15 s for older subjects. CONCLUSIONS: While a decrease of more than 2 log units is not likely to occur under most operational conditions, it is certainly possible, and pilots should be aware that significant risk can be incurred by setting cockpit instruments to luminance levels below 0.03 fL.

Spontaneous intrahepatic hemorrhage and hepatic rupture in the HELLP syndrome: four cases and a review.

Subcapsular hemorrhage and hepatic rupture are unusual catastrophic complications of the HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome. A high index of suspicion and prompt recognition are keys to proper diagnosis and management of affected patients. The optimal management of these patients is evolving. An aggressive multidisciplinary approach has considerably improved the morbidity and mortality associated with these complications. We present our experience with four cases of hepatic hemorrhage occurring in association with the HELLP syndrome and review the literature on this subject. All of our patients were multiparous, and three had a history of eclampsia/preeclampsia in a previous pregnancy. All four patients developed intrahepatic hemorrhage; two developed hepatic rupture requiring surgical intervention. Three patients developed disseminated intravascular coagulation and acute renal failure. Two patients developed pericardial effusion, pleural effusions, and ascites. One patient died of septic complications after multiple surgical interventions.

Dissection of an iliac artery conduit to liver allograft: treatment with an endovascular stent.

Hepatic artery thrombosis remains one of the most serious complications after orthotopic liver transplantation. Sepsis, biliary leakage and strictures, and retransplantation are often the result of this devastating complication. Because retransplantation or reoperation is sometimes not possible or advisable, other means of reestablishing hepatic artery continuity are desirable. We describe a liver transplant recipient who developed a dissection of an iliac artery conduit after retransplantation that was treated with fibrinolytic therapy followed by successful placement of an endovascular stent.

Utility of endoscopic evaluations in liver transplant candidates.

OBJECTIVE: The aim of this study was to determine whether endoscopic evaluation of patients referred for liver transplant evaluation contributes significantly to patient selection or management. METHODS: Esophagogastroduodenoscopy (EGD) was performed in transplant candidates who had not undergone this examination within a previous 6-month period. Colonoscopy (CSP) was performed if the patient was >50 yr of age or had anemia, a history of colonic pathology such as adenomatous polyps, or a history suggesting gastrointestinal tract abnormalities. RESULTS: A total of 118 patients were studied. EGD was performed in 74 (63%) patients. Forty-seven patients had esophageal varices identified; in 26, this represented a new diagnosis. Other findings on EGD included portal gastropathy (21 patients), gastric varices (seven patients), peptic ulceration (10 patients), Barrett's esophagus (three patients), and one case each of esophageal and gastric carcinoma. CSP was performed in 56 patients. Findings included adenomatous polyps (24 patients) and one case of colon carcinoma. Overall, gastrointestinal pathology was discovered in 67 (57%) of the patients undergoing endoscopic evaluation as part of our study. Alterations in patient selection or management resulted from 44% of the procedures performed; 42% of the patients were affected by these management changes and 2.5% of patients were removed from further transplant evaluation because of the diagnosis of malignancy. CONCLUSION: Endoscopic evaluation of liver transplant candidates often identifies important gastrointestinal pathology and frequently impacts patient selection and management before OLT.

Is melatonin associated with the development of autoimmune hepatitis?

Melatonin is a neurohormone produced by the human pineal gland that plays a role in the regulation of many physiologic processes and has been proposed as a therapy for everything from insomnia to metastatic carcinoma. Melatonin is available in the United States without prescription, and adverse effects appear to be uncommon. However, because melatonin appears to have immunomodulatory properties, the potential exists for the development of autoimmune-related side effects. We describe a patient in whom characteristic clinical and laboratory features of autoimmune hepatitis developed after beginning melatonin therapy for the treatment of insomnia. Liver biopsy demonstrated histologic features of autoimmune hepatitis. Rapid symptomatic and biochemical improvement resulted from the initiation of immunosuppressive therapy; however, hepatitis recurred after the withdrawal of steroid therapy. The temporal relation observed between melatonin use and the development of autoimmune hepatitis raises the possibility that the drug might be involved in the pathogenesis of this patient's autoimmune disease.

Outcomes of patient disengagement policies: implications for managed care.

The gastroenterology division at Wilford Hall Medical Center (WHMC) refers approximately 70% of outpatient consultations to civilian providers, a policy known as disengagement. This policy was implemented in the hope of reducing waiting times for appointments and testing. We conducted a telephone survey to determine whether disengaged patients eventually obtained health care and, if they did not, the reasons for this. We also attempted to determine the level of patient satisfaction with this policy. The results demonstrated that many patients did not obtain care within the 6-month follow-up period, largely because of financial considerations. Most patients were also dissatisfied with the policy and disappointed at not having obtained care at WHMC. The results of this study have important implications for Tricare, which might result in impaired access to care through out-of-pocket patient expenses related to cost-shares and membership fees.

Preneoplastic conditions of the liver.

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. The majority of patients who develop HCC have underlying cirrhosis, which suggests that cirrhosis itself represents a preneoplastic condition. Nevertheless, whereas patients with cirrhosis of any origin are at increased risk of developing HCC, those with chronic hepatitis B or C infection seem to be at greatest risk. Patients with cirrhosis resulting from chronic alcohol use, hemochromatosis, autoimmune hepatitis, or alpha-1 antitrypsin deficiency have less risk of developing this cancer, and some hepatic diseases, such as primary biliary cirrhosis and Wilson's disease, do not predispose affected persons to an appreciable risk of developing HCC. Certain histological features, such as liver cell dysplasia and macroregenerative nodules, may represent preneoplastic alterations of hepatocytes, but these changes do not seem to be a necessary step in the evolution of liver cancer. The pathogenesis of HCC is unclear, but seems to involve several steps. Hepatitis B virus infection may result in the malignant transformation of hepatocytes by some directly oncogenic mechanism, whereas other necroinflammatory conditions probably predispose to the development of HCC through the introduction of genetic alterations coupled with a reduction of genetic repair functions. Screening patients at risk for the development of HCC using alpha fetoprotein measurements and ultrasonography is widely practiced despite inconclusive evidence of efficacy. If screening is performed, the program used should be tailored to the perceived risk for a particular patient.

Transjugular intrahepatic portosystemic shunt improves oxygenation in hepatopulmonary syndrome.

Hepatopulmonary syndrome is a complication of chronic liver disease in which arterial hypoxemia results from abnormalities in pulmonary blood flow. Severe hypoxemia can lead to clinical deterioration and death. Although the etiology is unknown, portal hypertension seems to be an important factor in the development of hepatopulmonary syndrome. No effective pharmacological therapy has been identified, but liver transplantation may be curative. Arterial hypoxemia may complicate transplant surgery, however, and resolution of the syndrome after liver transplantation is performed may be delayed. In addition, it seems that complete reversal of oxygenation abnormalities after liver transplantation is performed is unpredictable. We described a patient with hepatopulmonary syndrome who noted improvement in symptoms of dyspnea after the placement of a transjugular intrahepatic portosystemic shunt. Arterial oxygenation and calculated shunt fraction improved significantly during the follow-up period, and liver transplantation was subsequently performed without difficulty. Portal decompression using transjugular intrahepatic portosystemic shunt may represent a palliative therapy for hepatopulmonary syndrome in patients awaiting liver transplantation.

Hepatic encephalopathy after transjugular intrahepatic portosystemic shunts: incidence and risk factors.

OBJECTIVES: The aim of this study was to determine the incidence of new or worsened hepatic encephalopathy after transjugular intrahepatic portosystemic shunts (TIPS) and to ascertain which clinical characteristics are associated with this complication. METHODS: At the University of California, San Francisco, over 22 months, TIPS were placed successfully in 108 adults. Seventy-seven patients in whom it was possible to assess the development of encephalopathy comprised the study population. Clinically significant encephalopathy was assessed at protocol clinic follow-up and, in some cases, by phone contact with the patient and the referring physician. Post-TIPS encephalopathy was defined as new onset of clinical encephalopathy requiring treatment or worsening of preexisting encephalopathy within 1 yr of TIPS. RESULTS: The overall incidence of new or worsened encephalopathy was 23% (18/77). Post-TIPS encephalopathy was well controlled with lactulose in 78% of cases and was progressive in 22%. Multivariate analysis showed that an increased risk of encephalopathy was associated with an etiology of liver disease other than alcohol [relative risk (RR) 9.2, p = 0.0052], female gender (RR 3.0, p = 0.029), and hypoalbuminemia (RR 2.2 for each 1 g/dl decrease, p = 0.044). CONCLUSIONS: Hepatic encephalopathy is a common complication of TIPS that can be controlled medically in most patients. The identification of clinical variables associated with an increased risk of encephalopathy may be useful in the selection of appropriate candidates for this procedure.

Novel short transcripts of hepatitis B virus X gene derived from intragenic promoter.

The hepatitis B virus X gene encodes a transcriptional trans-activator that appears essential for viral replication in the infected liver. It has been shown by others that at least two X protein products, initiating at different in-frame ATG codons within the X open reading frame, are necessary for full trans-activating function. Yet, previous studies have demonstrated only a full-length X gene transcript that extends 5' of the first ATG codon in the X open reading frame. In this communication, we present evidence for the existence of shorter X gene transcripts, whose heterogeneous 5' ends straddle the second ATG codon of the X open reading frame. These transcripts are not degradation products of the full-length X gene transcripts but rather arise from an independent promoter. Furthermore, immunofluorescence and functional analyses reveal that active X proteins are translated from these transcripts. Therefore, there appears to be a previously undescribed promoter embedded within the X open reading frame that can give rise to functionally important transcripts.

Fulminant hepatic failure.

FHF is an uncommon but devastating condition affecting otherwise healthy persons which causes significant morbidity and mortality. The etiologic factor is most commonly viral infection, with drugs and metabolic disorders being relatively less common causes. Hopefully, newer diagnostic techniques such as PCR will increase our understanding of the causes and pathogenesis of this disorder. Medical management at the present time must focus on anticipating, preventing, and rapidly identifying and treating complications that may affect every major organ system. Encouraging research continues on the clinical application of hepatotrophic drugs and artificial liver support systems, both as potentially definitive therapies and as maintenance for patients awaiting transplantation. Consultation with physicians at a transplant center should be sought early in the course of the patient's hospitalization when OLT is being considered. Liver transplantation has dramatically changed the outlook for patients with FHF, with current survival rates in the 55% to 75% range. The continuing challenge for the transplant team is to allocate available donor organs to those patients who would not otherwise survive, but also to provide OLT in a timely fashion to ensure the best chance of post-transplantation recovery. Newer techniques such as heterotopic liver transplantation, reduced-size organ transplantation, and the utilization of living related donors may further improve the survival of these patients.

Elastic interactions of photosynthetic reaction center proteins affecting phase transitions and protein distributions.

Reaction-center proteins of Rhodopseudomonas Sphaeroides reconstituted into phosphatidylcholine vesicles shift and broaden the fluid-gel transition of the lipid bilayer. The amount of broadening and temperature shift of the transition depend both on protein concentration and on lipid chain length. In particular, the direction of the transition temperature shift is very sensitive to lipid chain length. Electron micrographs show homogeneous protein distribution on the fluid surface whereas the solid phase contains protein aggregates the type depending on chain length. The results can qualitatively be understood in the framework of a mattress model of lipid/protein interactions in membranes.

Two-dimensional electron transfer from cytochrome C to photosynthetic reaction centers.

The arrangement and the electron transfer are studied for photosynthetic reaction centers (RC) of Rhodopseudomonas sphaeroides reconstituted into phospholipid vesicles. Freeze-etch electron micrographs of phase separated mixed vesicles reveal an RC enrichment in the phase containing the acidic lipid serine. It is demonstrated that the electron transfer from cytochrome c to RC involves a two-dimensional diffusion of the membrane bound electron donor with diffusion coefficients (D approximately 10(-9) cm2/sec) characteristic for membrane proteins.

Comparison of a reality orientation program for geriatric patients with and without music.

Reality orientation (RO) is a technique used with patients exhibiting confused or disoriented behavior. The purpose of RO is to reverse or halt confusion, social withdrawal, and apathy characteristic of elderly institutionalized patients. The purpose of this study was to compare the effects of a traditional versus music-based RO program. Eight residents of the Chateau de Notre Dame Nursing Home were randomly assigned to experimental and control groups. A pretest was administered to identify any significant differences in RO and behavior functioning between the two groups. The specific goals and objectives for the RO program were then formulated from information gathered on the pretest. The experimental group received two 30-minute music-based RO sessions a week for 8 weeks, while the control group received the same number of traditional RO sessions without music. Upon completion of the treatment, the posttest was administered to each subject. A two-way "mixed effects" analysis of variance was used to analyze the data. A significant interaction (p less than .05) was found between the groups and the treatment condition, with the control group remaining at the same level across trials and the group receiving the music-based RO showing marked improvement.