In-vitro and in-vivo evaluation of a new amphotericin B emulsion-based delivery system

The in-vitro and in-vivo toxicity and activity of a new emulsion-based delivery system for amphotericin B (AmB-E) and of deoxycholate-amphotericin B (Fungizone) were studied. In vitro, Candida albicans and human red blood cells (RBCs) were treated with either product and dose-response curves for various cellular effects (changes in potassium cell content, haemoglobin leakage from RBCs and colony-forming ability of fungal cells) were obtained. AmB-E was less toxic than Fungizone against human RBCs and equally active against C. albicans cells. In-vivo studies showed that the LD50 of AmB-E and Fungizone in noninfected OF1 mice were 7.24 and 3.46 mg/kg, respectively. The therapeutic efficacy of AmB-E was assessed in murine candidiasis. Firstly, the efficacy of equal doses (0.8 mg/kg) of AmB-E and Fungizone was evaluated in infected mice. Both formulations increased the survival time compared to the control and were equally effective in reducing the cfu counts in the kidney. In the same model of infection, the maximum tolerated doses (MTD) of Fungizone and AmB-E were determined in order to study the efficacies of Fungizone and AmB-E at their respective MTD. AmB-E significantly increased the number of long-term survivors compared with Fungizone (MTD:2 and 1 mg/kg, respectively). Thus, AmB-E was more effective than Fungizone for treatment of systemic mycoses at the MTD.

Relationship between NO-synthase activity and TNF-alpha secretion in mouse macrophage lines stimulated by a muramyl peptide entrapped in nanocapsules

The present study evaluates the ability of a new drug carrier: nanocapsules of poly(D,L-lactide) containing muramyldipeptide-L-alanyl-cholesterol (MTP-Chol NC) to induce activation of mouse macrophage cell lines. MTP-Chol NC stimulated nitric oxide (NO) expression and tumor necrosis factor-alpha (TNF-alpha) production, these are two important mediators of macrophage-mediated cytotoxicity. The encapsulated form was more effective than free muramyldipeptide, at low immunomodulator concentrations. The dose-response curves were completely different for NO and TNF-alpha, implying different regulatory mechanisms. In RAW 264.7 cells, the addition of anti-TNF-alpha antibodies during the activation period did not affect the level of nitrite induced by MTP-Chol Nc and lipopolysaccharide. Therefore, autocrine stimulation by TNF-alpha did not contribute to NO production. On the other hand, the presence of an NO synthase inhibitor led to an increase in TNF-alpha secretion. In J774.A1 cells, which were activated by MTP-Chol NC and interferon-gamma, TNF-alpha production seemed to act as a second messenger. Thus, under certain conditions, NO can play a role in modulating the cytotoxic activities of mouse macrophages.

Early assessment of outcome by ST-segment analysis after thrombolytic therapy in acute myocardial infarction

As an early marker of outcome, the sum of ST-segment elevation resolution between the electrocardiogram before and 3 hours after initiation of thrombolysis was investigated in 77 patients with acute myocardial infarction. Prospectively, three groups were defined according to complete (> or = 70%, n = 34), partial (< 70% to > or = 30%, n = 26), or no (< 30%, n = 17) ST resolution. There were considerable differences in the enzyme-determined infarct size (alpha-hydroxybutyrate dehydrogenase release for complete, partial, and no ST resolution: 529 +/- 397 IU/L, 689 +/- 484 IU/L, and 1293 +/- 742 IU/L, respectively; p = 0.0001) and the angiographic left ventricular function 1 week later (ejection fraction 58% +/- 10%, 53% +/- 13%, and 43% +/- 12%, respectively, p < 0.01; regional dyssynergic area 24 +/- 19, 39 +/- 23, and 50 +/- 21 U2, respectively, p < 0.01). Early reperfusion as assessed by creatine kinase release measured in 15-minute intervals was 90%, 65%, and 18%, respectively (p = 0.0001). Differences in degrees of ST-elevation resolution at 3 hours may help facilitate timely screening of patients for appropriate therapeutic intervention. Patients with complete ST resolution may be considered for early discharge, and patients with no ST resolution may be candidates for an early invasive approach or additional thrombolytic therapy.

Studies on manifestations of canine distemper virus infection in an urban dog population

An upsurge of canine distemper was recognized at the beginning of 1991 in the urban dog population of the Copenhagen area. The outbreak had the characteristics of a virulent morbillivirus introduction in a partly immune population, where the disease primarily was manifested in young individuals. Testing of single serum samples for the presence of canine distemper virus (CDV) IgM antibodies using an IgM ELISA confirmed current and recent CDV infections in an urban dog population, where the use of attenuated CDV vaccines was widespread. In 49 out of 66 sera from clinical cases suspected of canine distemper we detected CDV IgM antibodies, as compared to the detection of viral antigen by indirect immunofluorescence in 27 of 65 specimens of conjunctival cells. The antigenic make-up of isolates from acute and subacute clinical cases was investigated with a panel of 51 monoclonal antibodies directed against CDV and the related phocine distemper virus. The isolates exhibited an homogeneous reaction pattern and shared overall antigenic characteristics of the CDV prototype. The majority of cases were diagnosed among unvaccinated dogs and individuals with unknown or obscure vaccination record. However, severe clinical cases were also diagnosed in vaccinated individuals.

High stimulatory activity of dendritic cells from diabetes-prone BioBreeding/Worcester rats exposed to macrophage-derived factors

Dendritic cells (DC) present antigen and initiate T cell-mediated immune responses. To investigate the possible association of autoimmunity with DC function, we compared the accessory activity of splenic DC from Wistar/Furth (WF) and diabetes-prone (DP) BioBreeding (BB) rats. The latter develop autoimmune diabetes and thyroiditis. DC function was quantified in vitro by measuring T cell proliferation in mitogen-stimulated and mixed lymphocyte reactions. When purified without macrophage coculture, WF and DP DC displayed similar levels of accessory activity. In contrast, when purified by a method involving coculture with macrophages, DC from DP rats consistently displayed greater accessory activity. This finding could not be explained by morphological or phenotypic differences between DP and WF DC. In accessory activity assays performed after reciprocal DC cocultures with DP and WF macrophages, DP DC exhibited higher accessory activity irrespective of macrophage donor strain. We also compared the accessory activity of WF and DP DC cultured in the presence of conditioned medium and a mixture of IL-1 and GM-CSF. In all assays, DP DC exhibited higher accessory activity. In studies of (WF x DP) F1 hybrids, the high accessory activity of DP DC was observed to be heritable, and studies of WF and DP radiation chimeras indicated that the effect was an intrinsic property of the DP hematopoietic system. We conclude: (a) splenic DC from DP and WF rats possess similar basal levels of accessory potency; (b) after interaction with macrophages, DC of DP origin are capable of greater stimulatory activity than are WF DC; and (c) the mechanism responsible for this phenomenon involves differential responsiveness of DP and WF DC to macrophage-derived factors such as IL-1 and GM-CSF.

Antigenic relationships between field isolates of morbilliviruses from different carnivores

The antigenic relationships between PDV and isolates of morbilliviruses from carnivores suffering from distemper were investigated. Fourteen isolates, originating from terrestrial carnivores and harbour seals from 1985-1991 from Denmark, Norway, Greenland, and the U.S.A. were reacted in IFA and ELISA with monoclonal antibodies (MAbs) directed against four virion proteins (NP, P, F, and H). The MAbs comprised a newly completed panel of 36 anti-PDV MAbs and 39 previously developed anti-CDV MAbs. The antigenic make-up of the isolates separated them into the CDV prototype group and the PDV prototype group, having the antigenic characteristics of the reference vaccine strains of CDV and the Danish PDV isolate, respectively. The minor antigenic variations within the CDV group contrasted markedly to the differences encountered between the CDV and PDV group. The PDV group included isolates made in 1988 from diseased seals of Danish and Norwegian waters and isolates made in 1989 from distemper outbreaks in Danish mink farms. In contrast, the other distemper isolates investigated, including isolates from 1986 from a corresponding Danish mink farm, revealed the antigenic characteristics of CDV. Our results strongly indicate that PDV was recently transmitted from diseased seals to terrestrial carnivores causing distemper epizootics among farmed mink.

The identification, purification, and characterization of a pancreatic beta-cell form of the microtubule adenosine triphosphatase kinesin

Microtubules have been implicated as being necessary for the secretion of insulin from beta-cells, although the mechanism by which cytoplasmic microtubules contribute to the release of insulin is unknown. Kinesin is a microtubule-dependent adenosine triphosphatase (ATPase) that is thought to be responsible for the intracellular transport of vesicles and organelles. In this manuscript, the purification and preliminary characterization of a beta-cell form of kinesin is described. A 120-kilodalton antikinesin-reactive polypeptide was identified on blots when cultured insulinoma tumor cell lines were subjected to immunoblot analysis using monoclonal antibodies specific for the heavy chain of mammalian kinesin. The beta-cell form of kinesin was isolated from solid rat insulinoma tumors by cosedimentation of the kinesin with microtubules from tissue homogenates in the presence of adenylyl-imidodiphosphate. The beta-cell kinesin was further purified by gel filtration chromatography, and then the pure enzyme was characterized using in vitro assays. Although beta-cell kinesin showed little ATPase activity alone, the enzyme exhibited considerable ATP hydrolysis activity in the presence of taxol-stabilized microtubules. Moreover, in motility assays beta-cell kinesin was able to translocate microtubules across microscope coverslips in the presence of Mg(2+)-ATP. In summary, we report the identity of a novel islet beta-cell form of the microtubule-dependent ATPase kinesin and suggest a possible contribution of the microtubule cytoskeleton in insulin secretion.

Evaluation of the hepatotoxicological effects of a drug in an in vivo/in vitro model

Both in vivo and in vitro models have certain disadvantages for the study of the chronic hepatotoxicity of drugs. The aim of this work was to evaluate a new approach based on an in vivo/in vitro model. After chronic in vivo treatment of rats with Vincamine and Vindeburnol (an eburnamenine derivative which exhibits hepatotoxic properties in man) liver cells were isolated, and functional and metabolic disorders (metabolic utilization of fructose and protein biosynthesis) were studied to determine injury. The results showed no modification of blood parameters, but a direct relationship between the dose of Vindeburnol administered in vivo and the metabolic disorders observed in vitro, evidencing the high sensitivity and reliability of this model.

Nonreplicating viral vectors as potential vaccines: recombinant canarypox virus expressing measles virus fusion (F) and hemagglutinin (HA) glycoproteins

The development of canarypox virus (CPV) recombinants expressing the hemagglutinin (HA) and fusion (F) glycoproteins of measles virus (MV) is described. Inoculation of the CPV-MV recombinants into avian or nonavian tissue culture substrates led to the expression of authentic MVF and MVHA as determined by radioimmunoprecipitation and surface immunofluorescence. In contrast to avian-derived tissue culture, no productive replication of the CPV recombinant was evident in tissue culture cells derived from nonavian origin. On inoculation of dogs, a species restricted for avipoxvirus replication, the recombinants elicited a protective immune response against a lethal canine distemper virus (CDV) challenge. The level of MV neutralizing antibodies and the level of protection induced against CDV challenge achieved by the host-restricted CPV vector were equivalent to that obtained by vaccinia virus vectors expressing the same MV antigens.

Comparative studies of protein biosynthesis: the main experimental parameters in pulse and pulse-chase experiments must be standardized

The influence of experimental conditions was investigated in pulse and pulse-chase experiments involving L-[35s]methionine incorporation by isolated rat hepatocytes. The incorporation of the labelled amino acid must be linear as a function of dose and time, and similar hepatocyte densities should be used to compare radioactive uptake. High hepatocyte densities give greater precision. In pulse-chase experiments, it was shown that a pool of free radioactivity moves progressively during the chase phase from the intracellular compartment. Protein-associated radioactivity must therefore be expressed as a function of both total radioactive uptake and total labelled protein.

Asialoglycoprotein receptor in human isolated hepatocytes from normal liver and its apparent increase in liver with histological alterations

We have characterized a binding site for galactosyl terminal glycoproteins in hepatocytes isolated from human biopsies. The binding of asialoorosomucoid on hepatocytes previously treated by Triton X-100 was saturable, calcium-dependent and highly affine (Ka = 1.11 +/- 0.87.10(9) M-1) thus corresponding to a ligand-receptor binding. The total number of receptors in the normal human liver was 140,000 +/- 65,000 sites per cell. This corresponded to the value obtained in the human hepatoma cell line HepG2, but was significantly lower than for isolated rat hepatocytes. Furthermore, in hepatocytes isolated from livers with histological features of either fibrosis, cirrhosis, hepatocarcinoma with cirrhosis or nodular regenerative hyperplasia, the number of asialoglycoprotein receptors per cell was increased, while the binding affinity was unchanged.

Vaccinia virus recombinants expressing either the measles virus fusion or hemagglutinin glycoprotein protect dogs against canine distemper virus challenge

cDNA clones of the genes encoding either the hemagglutinin (HA) or fusion (F) proteins of the Edmonston strain of measles virus (MV) were expressed in vaccinia virus recombinants. Immunofluorescence analysis detected both proteins on the plasma membranes of unfixed cells as well as internally in fixed cells. Immunoprecipitation of metabolically radiolabeled infected-cell extracts by using specific sera demonstrated a 76-kDa HA polypeptide and gene products of 60, 44, and 23 kDa which correspond to a MV F precursor and cleavage products F0, F1, and F2, respectively. Neither recombinant induced cell fusion of Vero cells when inoculated individually, but efficient cell fusion was readily observed upon coinfection of cells with both recombinants. Inoculation of dogs with the vaccinia virus-MV F recombinant (VV-MVF) did not give rise to detectable MV-neutralizing antibody. Inoculation of dogs with the vaccinia virus-MV HA recombinant (VV-MVHA) or coinoculation with both recombinants (VV-MVF and VV-MVHA) induced significant MV-neutralizing titers that were increased following a booster inoculation. Inoculation of dogs with the vaccinia virus recombinants or with MV failed to induce canine distemper virus (CDV)-neutralizing antibodies. Upon challenge with a lethal dose of virulent CDV, signs of infection were observed in dogs inoculated with (VV-MVF). No symptoms of disease were observed in dogs that had been vaccinated with VV-MVHA or with VV-MVHA and VV-MVF and then challenged with CDV. All dogs vaccinated with the recombinant viruses as well as those inoculated with MV or a vaccine strain of CDV survived CDV challenge.

Laparoscopic cholecystectomy: a multicenter study

Laparoscopic cholecystectomy has been developed as an alternative to open cholecystectomy for the treatment of symptomatic cholelithiasis. A collaborative study of 261 patients undergoing laparoscopic cholecystectomy at three Texas institutions was performed to determine the effectiveness and safety of this technique. There were 65 males and 196 females with a mean age of 49 years (range 17-94 years). Acute cholecystitis was present in 38 patients and chronic cholecystitis in 223 patients. Mean length of surgery was 80 minutes (20 min to 4 hr). Fifteen patients were converted to the open technique intraoperatively due to bleeding, adhesions, or difficulty of dissection. There were no perioperative deaths and morbidity was 3% including urinary retention, small bowel obstruction, arrhythmia, wound infection, and bile leakage. There were no common duct injuries. Hospitalization ranged from outpatient surgery to 7 postoperative days with a mean of 1.2 days. We conclude that laparoscopic cholecystectomy can be performed safely and with low morbidity and offers shorter hospitalization and postoperative recovery.

Scabies presenting as bullous pemphigoid-like eruption

Several diseases, at times, may be confused with scabies. We report the diagnosis and treatment of scabies in two patients. Their eruptions recurred and persisted and eventually developed blisters. The skin biopsy specimens submitted for light microscopy and immunofluorescence were considered to be consistent with bullous pemphigoid. Both patients were treated successfully with lindane and remained disease free for up to 6 months of follow-up.

Expression of reg/PSP, a pancreatic exocrine gene: relationship to changes in islet beta-cell mass

A cDNA termed reg was recently isolated by differential screening of a library prepared from regenerating islets isolated from pancreatic remnants of rats subjected to 90% pancreatectomy and nicotinamide treatment. This led to speculation that this gene may be involved in expansion of beta-cell mass. In the current study we have measured reg expression after implantation and resection of a solid insulinoma tumor into rats, maneuvers known, respectively, to reduce and reexpand the volume of beta-cells in the islet. Animals with an implanted insulinoma tumor became profoundly hypoglycemic. Islet beta-cells declined from the normal 75% of total islet volume to less than 30%, in concert with a marked reduction in the reg mRNA level. Removal of the tumor resulted in a sharp increase in beta-cell replication, as measured by [3H]thymidine incorporation and a return to normal beta-cell volume within 4 days of tumor resection. This was associated with a transient induction in reg expression compared to that in tumor-bearing animals, effectively returning the amount of reg mRNA to the levels found in normal animals within 48 h; at later time points after tumor removal (3-7 days) reg expression declined, but then rose toward normal. In situ hybridization analysis localized the initial induction in reg mRNA expression to the exocrine pancreas. Continuous infusion of insulin into normal rats for 4 days, a maneuver that does not significantly reduce beta-cell mass, resulted in dramatically reduced insulin mRNA in islets, but no change in the levels of reg mRNA. We conclude that the diminution in pancreatic beta-cell mass caused by subcutaneous implantation of an insulinoma is associated with reduced reg gene expression and that the increase in beta-cell replication after resection of the tumor is preceded by return of reg gene expression toward normal.

[Magnetic resonance tomography of the shoulder. Possibilities of over interpretation of normal findings]

In order to test the criteria for abnormalities of the shoulder as seen on MR, 30 normal shoulders were examined. The examination included T1, proton and T2-weighted SE sequences and T2*-weighted FE sequences, using transverse, oblique coronary and oblique sagittal planes. In 57% there was increased signal intensity in the tendon of the rotator cuff; this might have been interpreted as a rupture of the cuff or tendinitis. Anatomical examination suggests that the finding is due to a normal layer between the long head of the biceps and the tendon joint complex. The anterior glenoid labrum could not be clearly delineated in 57% and the posterior labrum in 5%. In two cases there was a superior, postero-lateral defect in the head of the humerus. The currently accepted criteria for the MRT diagnosis of shoulder abnormalities need to be critically re-evaluated.

Effect of streptozotocin-diabetes on rat liver asialoglycoprotein receptor turnover: in vivo degradation and in vitro biosynthesis

The metabolic turnover of the Hepatic Binding Protein (HBP) was investigated in streptozotocin-diabetic rats. We have already shown that diabetes induced a decreased ligand binding capacity while the immunoreactive HBP was normal. To explore the eventual modifications due to diabetic state upon the turnover of HBP, we followed the in vivo degradation of HBP and its biosynthesis in vitro. After in vivo labelling with L-[3H] leucine and purification of HBP from rat livers, we found a 20% decrease in diabetic HBP half-life. By in vitro incubations of freshly isolated hepatocytes and a 2 h-pulse in the presence of L-[35S] methionine, we showed that diabetes provokes an increased uptake of L-[35S] methionine in hepatocytes allowing an augmented synthesis of HBP although the L-[35S] methionine incorporation into total proteins was less efficient.

Cytotoxicity of S-(1,2,3,4,4-pentachlorobutadienyl)-L cysteine after apical and basolateral exposure of LLC-PK monolayers. Involvement of an amino acid transport system

Glutathione conjugation and subsequent formation of cysteine conjugates are key steps in the nephrotoxicity of halogenated alkenes. In this metabolic activation several organs are involved. However little is known about the transporters responsible for the uptake of cysteine conjugates. Recent evidence suggest that amino acid transporters play a role in this uptake. Monolayers of LLC-PK1 cells, a kidney cell line, were exposed to S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine (PCBD-CYS). Cytotoxicity was used as a parameter for PCBD-CYS uptake. Basolateral exposure (1 h: 400 microM and 16 h: 25 microM) to PCBD-CYS resulted in a much higher aminooxyacetic acid inhibitable cytotoxicity than apical exposure, suggesting a preferential basolateral uptake of PCBD-CYS. Exposure to PCBD-CYS in the absence of sodium did not result in a decrease of the cytotoxicity, suggesting a sodium independency of the PCBD-CYS uptake. Amino acids and amino acid analogues were used as diagnostic compounds in the further identification of the PCBD-CYS transporter. In cis-inhibition experiments monolayers were co-incubated with PCBD-CYS and these diagnostic compounds during one hour. System L substrates such as 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid (BCH) and cycloleucine did not inhibit cytotoxicity. D-Tryptophan, a model inhibitor of System T, caused a strong inhibition. System L has, in contrast to System T, a high sensitivity to trans-stimulation. Pre-loading the monolayers with the diagnostic compounds should cause an increase in cytotoxicity when System L is involved. Neither System L substrates such as BCH and cycloleucine nor D-tryptophan increased cytotoxicity. These results suggest a preferential basolateral uptake of PCBD-CYS in LLC-PK1 monolayers and involvement of an amino acid transporter with characteristics of System T.

Effects of hypoglycemia and prolonged fasting on insulin and glucagon gene expression. Studies with in situ hybridization

In situ hybridization of proinsulin and proglucagon mRNA was performed in rat pancreas to assess prohormone gene expression during various glucopenic conditions. During a 4-d fast mean blood glucose declined by 48 mg/dl; proinsulin mRNA signal density remained normal while proglucagon mRNA signal density more than doubled. At the end of a continuous 12-d insulin infusion blood glucose averaged 53 +/- 12 mg/dl; proinsulin mRNA signal density declined to 30% of controls while proglucagon mRNA signal density more than doubled. In insulinoma-bearing NEDH rats blood glucose averaged 34 +/- 3.5 mg/dl; the proinsulin mRNA signal was virtually undetectable and proglucagon mRNA signal density was more than twice the controls. There was no detectable change in either beta-cell area or islet number in rats subjected to fasting or insulin infusion, but in insulinoma-bearing rats beta cell area was markedly reduced. Thus compensation during 4 d of starvation involves an increase in glucagon gene expression without change in insulin gene expression or beta cell mass. In moderate insulin-induced hypoglycemia glucagon gene expression is increased and insulin gene expression decreased. In more profound insulinoma-induced hypoglycemia, in addition to the foregoing changes in hormone gene expression, there is a profound reduction in the number of insulin-expressing cells.

[Morphology of the adductor hallux muscle and its significance for the surgical treatment of hallux valgus]

The Mc Bride procedure for surgical treatment of the hallux valgus varies according to the different morphological features of the M. adductor hallucis. One hundred specimens of human adult feet-some with a hallux valgus deformity- were preserved in formaldehyde and examined under this aspect. The tendon of the M. adductor hallucis shows two heads-a caput transversum and a caput obliquum- and inserts at the basis as well as at the lateral sesamoid bone of the great toe. Morphological differences in type and place of confluence of both tendon heads give us a classification into 8 different types. In most cases the caput transversum inserted into the caput obliquum from the side and in the middle at the level of the lateral sesamoid bone of the great toe. In most cases, specimens with this muscle type showed a hallux valgus. In surgery of the hallux valgus deformity the tendon of the M. adductor hallucis should be detached from it insertion points in order to reduce the tension on the sesamoid bone and to prevent luxation. The insertion of the caput laterale of the M. flexor hallucis brevis at the lateral sesamoid bone should be left as it is.

The uncoupling protein dimer can form a disulfide cross-link between the mobile C-terminal SH groups

Isolated uncoupling protein (UCP) can be cross-linked, by various disulfide-forming reagents, to dimers. The best cross-linking is achieved with Cu2+-phenanthroline oxidation. Because cross-linking is independent of UCP concentration and prevented by SDS addition, a disulfide bridge must be formed between the two subunits of the native dimer. Cross-linking is prevented by SH reagent and reversed by SH-reducing reagents. In mitochondria, cross-linking of UCP with disulfide-forming agents is even more efficient than in isolated state. It proves that UCP is a dimer in mitochondria, before isolation. Disulfide-bridge formation does not inhibit GTP-binding to UCP. Cross-linked UCP re-incorporated in proteoliposomes either before or after cross-linking fully retains the H1-transport function. Rapid cross-linking by membrane impermeant reagents indicates a surface localization of the C-terminus in soluble UCP and projection to the outer surface in mitochondria. Intermolecular disulfide-bridge formation in a dimer requires juxtaposition of identical cysteines at the twofold symmetry axis. A rigid juxtaposition of cysteines is unlikely, unless intended for a native disulfide bridge. The absence of such a bridge in UCP suggests that juxtaposition of cysteines is generated by high mobility. In order to localize the cysteine involved, cross-linked UCP was cleaved by BrCN. The CB-7 C-terminal peptide, which contains cysteines at positions 287 and 304, disappears. Limited trypsinolytic cleavage, previously shown to occur at Lys-292, removed cross-linking in UCP both in the solubilized and mitochondrially bound state. The cleaved C-terminal peptide of 11 residues contains only cystein-304 which, thus, should be the only one (out of 7 cysteines in UCP) involved in the S-S bridge formation. Obviously, the C-terminal location of the cysteine, because of its high mobility, permits juxtapositioning for cross-linking. This agrees with predictions from hydrophobicity analysis that the last 14 residues in UCP protrude from the membrane.