Structure-function relationship in UCP1

The function of uncoupling protein (UCP1) as a H+ transporter regulated by nucleotide binding is elucidated. H+ transport requires fatty acids (FA) with relatively wide structural tolerance. The nucleotide binding site is specific for purine nucleotides and tolerates a number of derivatives. The strong pH dependency facilitates regulation of nucleotide binding and thus H+ translocation. The structure-function relationship of UCP1 has been analysed by various probes and by mutagenesis. According to our model, FA are a cofactor in H+ transport, providing H+ shuttling carboxyl groups in the translocation channel. By mutagenesis, additional H+ translocating groups at both sides of the translocation channel were found. Two pH sensors, controlling nucleotide binding, were identified in accordance with earlier postulates deduced from the pH dependence of nucleoside diphosphate (NDP) and nucleoside triphosphate (NTP). A common pH sensor E190 and a specific pH sensor H214 for triphosphates only, control access to the phosphate binding moiety. The three mitochondrial carrier family characteristic intrahelical arginines are essential for nucleotide binding. Mutagenesis of other charged residues reveals their role in structure stabilisation and/or has more generalised effects due to charge relay networks in UCP1.

Regulation of UCP3 by nucleotides is different from regulation of UCP1

UCP3 is an isoform of UCP1, expressed primarily in skeletal muscle. Functional properties of UCP3 are still largely unknown. Here, we report about the expression of UCP3 and of UCP1 in inclusion bodies of Escherichia coli. On solubilization and reconstitution into proteoliposomes, both UCP3 and UCP1 transport Cl- at rates equal to the reconstituted native UCP1. Cl- transport is inhibited by low concentrations of ATP, ADP, GTP and GDP. However, no H+ transport activity is found possibly due to the lack of a cofactor presents in UCP from mitochondria. The specificity of inhibition by nucleoside tri- and diphosphate is different between UCP1 and UCP3. UCP1 is more sensitive to tri- than diphosphate whereas in UCP3, the gradient is reverse. These results show a new paradigm for the regulation of thermogenesis at various tissues by the ATP/ADP ratio. In brown adipose tissue, the thermogenesis is correlated with a low ATP/ADP whereas in skeletal muscle, non-shivering thermogenesis is active at a high ATP/ADP ratio, i.e. in the resting state.

Turnover forehead flap combined with composite crus of helix graft for partial nasal reconstruction

Partial lateral nasal defects challenge the plastic surgeon both technically and aesthetically. Many methods for reconstruction of these defects have been described. We have used a turnover forehead flap in conjunction with composite auricular graft for the reconstruction of nasal defects. The forehead flap is turned over so that the forehead skin serves as internal lining in the nose. The composite auricular graft serves as external nasal lining and provides mechanical support to the ala. The technique was used in seven patients and is presented here with illustrations, selected cases, results, and conclusions concerning patient selection.

In the uncoupling protein (UCP-1) His-214 is involved in the regulation of purine nucleoside triphosphate but not diphosphate binding

The nucleotide binding to uncoupling protein (UCP-1) of brown adipose tissue is regulated by pH. The binding pocket of the nucleotide phosphate moiety has been proposed to be controlled by the protonization of a carboxyl group (pK approximately 4.5) for both nucleoside diphosphates (NDP) and nucleoside triphosphates (NTP) (identified as Glu-190) and of a histidine (pK approximately 7. 2) for NTP only. Here we identify His-214 as a pH sensor specific for NTP binding only. In reconstituted UCP-1 from hamster, DEPC diminishes binding of NTP but not of NDP. It also prevents inhibition of H+ transport by NTP but not by NDP. Hamster UCP-1 expressed in Saccharomyces cerevisiae was mutated to H214N resulting in only moderate change of the binding affinity for NTP (GTP) but a 10-fold affinity decrease with the bulkier substituent in H214W, whereas the affinity for NDP (ADP) was largely unchanged. The steep decrease with pH of the binding affinity for NTP in wild type (from pH 6.0 to 7.5) was much flatter in the mutants. Also, the pH dependence of binding and dissociation rates was diminished in these mutants. The transport of H+ and Cl- was not affected. Thus, His-214 is only involved in nucleotide binding, whereas, as previously shown, His-145 and His-147 are involved only in H+ transport. The results validate the earlier proposal of a histidine regulating the NTP binding in addition to a carboxyl group controlling both NTP and NDP binding. It is proposed that His-214 protrudes into the binding pocket for the gamma-phosphate thus inhibiting NTP binding and that His214H+ is retracted by a background -CO2- group to give way for the gamma-phosphate.

Macrophage treatment of pressure sores in paraplegia

This report describes two cases where wound healing was achieved by local injection of a macrophage suspension after conventional treatments had failed for many years

The use of porphyrins for eradication of Staphylococcus aureus in burn wound infections

The assessment of deuteroporphyrin-hemin complex as an agent for the treatment of burn wounds infected with a multiple-drug resistant strain of Staphylococcus aureus was performed. The effect of the porphyrin on the survival of the infectious bacteria was first assayed in culture, and later tested as well in a burned infected animal model. The addition of deuteroporphyrin and hemin, separately or together (as a complex) to a growing culture of S. aureus was monitored during 8 hours. It was found that deuteroporphyrin alone was strongly bactericidal only after photosensitization. On the other hand, hemin alone was moderately bactericidal but light independent. A combination of both deuteroporphyrin and hemin was extremely potent even in the dark and did not require illumination to eradicate the bacteria. The in vivo experiments by application of the above porphyrins in combination to infected burn wounds in guinea pigs was an effective way to reduce dramatically the contaminating S. aureus. Reduction of more than 99% of the viable bacteria was noted after the porphyrin mixture was dropped on the eschar or injected into the eschar, an effect that lasted for up to 24 hours. The deuteroporphyrin-hemin complex may be suggested as a new bactericidal treatment of S. aureus infected burns since it was found to be a potent and promising anti-Staphylococcal agent.

Vipera palaestinae snake envenomations: experience in children

In Israel, Vipera palaestinae (V. palaestinae) is the most common venomous snake, accounting for 100-300 reported cases of envenomation every year. However, V. palaestinae snakebites in children have not been extensively investigated. The demographic features, treatment and outcome of V. palaestinae envenomation in 37 children treated in two medical centers over a 9 year period were retrospectively reviewed. The victims age ranged from 2-18 years with a mean age of 8.9 years. Twenty-nine children were males and eight were females. Twenty-one patients resided in rural areas, and 16 children were living in urban areas. Twenty-three (63%) of the patients were bitten on the lower limb; Twelve (33%) on the upper limb, and two on the head or neck (4%). Using a grading scale of one to three from minimal to severe envenomation, 15 (40.5%), 15 (40.5%) and 7 (19%) patients had mild, moderate and severe envenomation, respectively. Major complications of envenomation that were manifested after arrival consisted of compartment syndrome (two patients) and respiratory dysfunction (two patients). Specific monovalent antiserum for the treatment of V. palaestinae bite was given to 16 children (43%) of whom, four patients were in the severe group, seven and five in the moderate and mild groups respectively. No patient suffered a significant infection, tissue loss, permanent disability or death. We conclude that early ICU admission along with close monitoring and antivenom therapy is important in reducing morbidity and mortality in children systemically envenomed by V. palaestinae.

Nasal reconstruction combined with dacryocystorhinostomy in a patient with absence of half of the nose

This article describes a rare case of unilateral arhinia (congenital absence of half of the nose), in which total nasal reconstruction was performed. A glass Jones tube was used to create a new nasolacrimal duct connecting the lumen of the existing lacrimal sac to the contralateral normal nasal cavity.

Identification of the pH sensor for nucleotide binding in the uncoupling protein from brown adipose tissue

The transport inhibiting nucleotide binding to the uncoupling protein (UCP) has a unique pH dependence and has been postulated to be controlled by the dissociation state of a carboxyl group in UCP with pK 4.5 and, in addition only for the nucleoside triphosphate, by a group with pK 7.2. To prove this assumption and to identify the carboxyl group, Woodward reagent K (WRK) was applied to UCP. In mitochondria, WRK was found to inhibit binding of GTP in a noncompetitive manner using WRK in the millimolar range. In isolated UCP, GTP binding is inhibited by WRK at a 1 to 2 ratio to UCP, suggesting that WRK primarily reacts with only one carboxyl group. Prebound GTP protects against WRK reaction as monitored by GTP binding. The protection decreases from pH 5 to 7 due to better reactivity of WRK and less tight GTP binding. WRK does not inhibit H+ transport by UCP but prevents GTP inhibition of H+ transport. For elucidating the WRK target residue, the WRK derivatized group was labeled with [3H] by reduction with [3H]NaBH4. Both GTP and GDP largely protected against WRK-dependent [3H] labeling. CNBr fragmentation identified the region T121-M197 as the [3H] incorporation site. Combined CNBr and tryptophane cleavage by the reagent 3-bromo-3-methyl-2-((2-nitrophenyl) thio)-3H-indole (BNPS) allowed to further delimit the 2.8 kDa peptide W173-M197 as the [3H] label carrier which contains two acid residues E190 and D195. To further identify the residue, limited tryptic digestion in sarcosyl-treated UCP was performed, and a tryptic fragment enclosing E190 and D195 was isolated which carried most of the [3H] label. Edman degradation showed the major [3H] label at the eighth position corresponding to E190 and no peak at D195. Thus, the original postulate of the pH-sensing carboxyl group regulating both the nucleoside di- and triphosphate binding has been verified. It is identified as E190 situated in the fourth transmembrane helix. In total, now four residues close to the nucleotide binding sites in UCP have been determined.

Enzyme-supported oil extraction from Jatropha curcas seeds

Jatropha curcas is a tropical plant widely distributed in arid areas. The seeds contain about 55% of oil, which is mainly used for the production of soap as a fuel and after transesterification as biodiesel. Various methods for recovering of oil from the seeds, including extraction with organic solvents and water, have been investigated. Compared to hexane extraction (98%) the oil extraction using water only yielded 38% of the total oil content of the seeds. Using several cell wall degrading enzymes during aqueous extraction a maximum yield of 86% was obtained. The influence of cellulolytic, hemicellulolytic enzymes, as well as proteases was studied. The experiments were carried out at different pH-values and temperatures to find out the optimum for oil recovering using enzymes. , Surprisingly, the best results (86%) were obtained using an alkaline protease. Combinations of proteases with hemicellulases and/or cellulases did not further increase the extraction yield. The enzyme-supported aqueous extraction offers a nontoxic alternative to common extraction methods using organic solvents with reasonable yields.

Effect of fatty acids on H+ transport activity of the reconstituted uncoupling protein

A detailed study on the activation of H+ transport by reconstituted uncoupling proteins from brown adipose tissue is given, including the influence of chain lengths and of other structural modifications, concentration dependence, and the influence of nucleotides. Uncoupling protein was reconstituted with phosphatidylcholine in such a way as to keep H+ transport with endogenous fatty acids at a minimum. Using excess of polystyrene beads on reconstitution avoided the complications arising from the use of albumin. Both delta psi-driven H+ uptake and H+ efflux systems are used by changing the polarity. Fatty acids stimulate H+ uptake up to 6-fold and H+ efflux more than 10-fold. There is no competition between the inhibition by nucleotides (GTP) and fatty acids. Also, the binding of GTP and ATP is not affected. Only fatty acids starting from C8 activate, reaching a maximum at C14. However, unsaturated homologous of C18 (oleic, linoleic, etc.) are fully active. Hydrophilic substitutions by hydroxyl, CO2H, bromo, doxyl groups also permit good activation, probably due to improved uptake into the lipid phase. The hydrophobic moiety exhibits a low specificity. Blockage of carboxyl by esterification abolishes the activation. Maximum activation requires high total concentrations of 200-300 microM. The distribution of fatty acids between proteoliposomes and solution was determined. The activation mode of fatty acids is discussed either as regulatory activators or as cofactors in H+ translocation involving their carboxyl groups. Two alternatives are considered, namely that the fatty acids carboxyl group is at the translocation center or in the channel facilitating H+ transfer to the constituent H(+)-translocating carboxyl groups.

Elongation by weight of a bipedicle hair-bearing neck flap

We report a patient in whom weight was applied to a tube flap that was raised as part of an upper lip reconstruction procedure. Because the flap was found too short for transfer, weight was applied and flap elongation was achieved within a few days.

Decreased serum cholesterol level after snake bite (Vipera palaestinae) as a marker of severity of envenomation

In 44 patients bitten by snakes (Vipera palaestinae), admission serum cholesterol levels were negatively correlated with severity of envenomation (mean +/- SD, 175 +/- 49, 137 +/- 36, and 96 +/- 40 mg/dl, respectively, in cases with mild, moderate, and severe clinical manifestations [p < 0.0001]). Concomitant decreases in serum albumin were not significant. These findings were supported by experimental results in rabbits, in which low, medium, and high doses of purified V. palaestinae venom (all in the non-lethal range), led to dose-dependent decreases in serum cholesterol, at 180 minutes, of 9.5% +/- 8.9%, 18.6% +/- 10.1%, and 32.7% +/- 11.8%, respectively (p < 0.01). This rapid decrease in serum cholesterol level is only partially explained by transcapillary lipoprotein leakage and probably indicates changes in lipoprotein transport and metabolism caused by the phospholipase A2 component of V. palaestinae venom. Admission total serum cholesterol level may serve as an indicator of severity of envenomation in patients bitten by snakes of the Vipera genus before full development of the clinical syndrome.

Use of flumazenil in the diagnosis and treatment of patients with coma of unknown etiology

OBJECTIVES

To evaluate the use of single-dose flumazenil in the diagnosis of coma of unknown etiology, and of continuous flumazenil infusion in the treatment of benzodiazepine-induced coma.

DESIGN

Prospective study.

SETTING

Emergency room and general medicine ward of a teaching hospital.

PATIENTS

A total of 42 comatose adults in whom metabolic, neurologic, or traumatic causes of coma were excluded.

INTERVENTIONS

a) Intravenous bolus injections of 0.25 mg flumazenil were given at 1-min intervals, either until improvement by two coma grades or a total dose of 2.0 mg was reached. b) Loading doses as in (a) followed by a maintenance infusion administered as long as indicated by repeated coma grade evaluation.

MEASUREMENTS AND MAIN RESULTS

a) Of 34 patients, 28 received only the flumazenil loading dose responded promptly. Twenty-one of 25 available urine samples of the responding patients contained only benzodiazepine metabolites. Four urine samples contained benzodiazepines in combination with other drugs. Six patients did not respond to the flumazenil loading dose. The urine of three patients contained a combination of benzodiazepines and another coma-exerting drug; the remaining three were negative. A total of 24 patients, who initially responded to flumazenil loading, deteriorated to their previous coma state and were admitted to the general medical ward. Six (25%) patients developed complications related to hospitalization and their bedridden state. b) Eight other patients, who deteriorated after an initial loading dose, received a second iv bolus of flumazenil, followed by maintenance infusions over 5 to 24 hrs. Their hospital course was uneventful.

CONCLUSIONS

These findings indicate that flumazenil is safe and effective in the diagnosis of benzodiazepine-induced coma. Furthermore, the use of continuous flumazenil maintenance infusion is of considerable therapeutic value in patients who exhibit deterioration after initial response to the single loading dose.

Derivatives of 1-beta-D-ribofuranosylbenzimidazole 3',5'-phosphate that mimic the actions of adenosine 3',5'-phosphate (cAMP) and guanosine 3',5'-phosphate (cGMP)

A series of new analogues of 1-beta-D-ribofuranosylbenzimidazole 3',5'-phosphate (cBIMP) has been designed according to the properties predicted by the MNDO method, and synthesised from substituted benzimidazoles. Dipole vectors and HOMO and LUMO energies for each benzimidazole base were calculated by the MNDO method and the lipophilicities of the cBIMP derivatives were determined. In general, the cBIMP derivatives activate cAMP-dependent protein kinases I and II and preferentially bind to site B, especially for the type II kinase, with 2-trifluoromethyl-cBIMP and 5,6-difluoro-cBIMP exhibiting the highest site selectivity. Each cBIMP derivative can stimulate cGMP-stimulated cyclic phosphodiesterase (cGS-PDE), with 5,6-dimethyl-cBIMP being as potent as cGMP, and also inhibit cGMP-inhibited phosphodiesterase (cGI-PDE). Only the 2-trifluoromethyl-cBIMP and the Rp-phosphorothioates (cBIMPS) (equatorial P = S) were resistant to hydrolysis by cPDE. The Sp-phosphorothioates were hydrolysed slowly, if at all. In addition to exhibiting a high lipophilicity, the most active compounds for the induction of apoptosis and inhibition of proliferation were also resistant to cPDE (Sp-5,6-dichloro-cBIMPS) and/or were potent activators of cAMP-dependent protein kinase (5,6-dichloro-cBIMP).

Mapping of the epitope/paratope interactions of a monoclonal antibody directed against adenosine 3',5'-monophosphate

A series of systematically modified cyclic AMP (cAMP) analogues, including newly synthesized benzimidazole ribofuranosyl 3',5'-monophosphates was used to map the essential molecular interactions between cAMP and the monoclonal antibody 4/2C2 (mab 4/2C2) directed against 2'-O-succinoyl cAMP [Colling, Gilles, Nass, Moka & Jaenicke (1988) Second Messengers Phosphoproteins 12, 123-133]. Its paratope binds the purine base in syn conformation by dipole-dipole interactions and hydrophobic forces and/or stacking interactions. The ribose phosphate moiety is recognized by a combination of charge interactions and H-bonds to the exocyclic and the 5'-oxygen atoms and a hydrophobic interaction at the 2'-position. There is no regioselectivity for the exocyclic oxygen atoms. Compared with the known types of binding, mab 4/2C2 thus shows a new combination of molecular interactions which may be the basis of its strikingly specific recognition and binding of the cyclic adenylates. On this account mab 4/2C2 may become an important tool in studies on cAMP metabolism.