SOOF lift and lateral retinacular canthoplasty

Eyelid rejuvenation surgery may be slowly shifting from pure fat removal techniques to those that preserve and reposition the periorbital fat. The traditional subciliary incision blepharoplasty was fraught with minor and major complications, and while the transconjunctival blepharoplasty afforded lower morbidity, its inability to address all aspects of periorbital rejuvenation eventually limited its popularity. Coincidentally, a search by aesthetic surgeons was on for better techniques to lift the midface, soften the nasolabial fold, and efface the tear trough deformity. In an effort to avoid the lid malposition complications that often accompany transblepharoplasty cheek lifting, innovative canthoplasty and canthopexy techniques were developed, which paved the way for a safe return to subciliary blepharoplasty surgery. Effacement of the tear trough deformity, now considered to be a major determinant in successful periorbital rejuvenation, could be achieved through fat repositioning and without the use of alloplastic implants or free fat grafts, thus improving reliability while minimizing complications. By preserving periorbital fat the hollowed out orbit, often seen after traditional blepharoplasty, could be avoided. The technique described in this article is a composite of several previously published approaches, is simple for the experienced blepharoplasty surgeon to master, and has been used with safety and reliability over the past 18 months in the senior author's practice.

Probing essential water in yeast pyrophosphatase by directed mutagenesis and fluoride inhibition measurements

The pattern of yeast pyrophosphatase (Y-PPase) inhibition by fluoride suggests that it replaces active site Mg(2+)-bound nucleophilic water, for which two different locations were proposed previously. To localize the bound fluoride, we investigate here the effects of mutating Tyr(93) and five dicarboxylic amino acid residues forming two metal binding sites in Y-PPase on its inhibition by fluoride and its five catalytic functions (steady-state PP(i) hydrolysis and synthesis, formation of enzyme-bound PP(i) at equilibrium, phosphate-water oxygen exchange, and Mg(2+) binding). D117E substitution had the largest effect on fluoride binding and made the P-O bond cleavage step rate-limiting in the catalytic cycle, consistent with the mechanism in which the nucleophile is coordinated by two metal ions and Asp(117). The effects of the mutations on PP(i) hydrolysis (as characterized by the catalytic constant and the net rate constant for P-O bond cleavage) were in general larger than on PP(i) synthesis (as characterized by the net rate constant for PP(i) release from active site). The effects of fluoride on the Y-PPase variants confirmed that PPase catalysis involves two enzyme.PP(i) intermediates, which bind fluoride with greatly different rates (Baykov, A. A., Fabrichniy, I. P., Pohjanjoki, P., Zyryanov, A. B., and Lahti, R. (2000) Biochemistry 39, 11939-11947). A mechanism for the structural changes underlying the interconversion of the enzyme.PP(i) intermediates is proposed.

The molecular basis of cystic fibrosis in South Africa

The spectrum of CFTR mutations in three South African populations is presented. To date. a total of 192 white patients (384 chromosomes) with confirmed CF have been tested. deltaF508 accounts for 76% of the CF chromosomes in this group, with 3272-26A-->G, 394delTT and G542X occurring at the following frequencies: 4, 3.6 and 1.3%, respectively. A further 11 mutations account for 6% of CF chromosomes. A total of 91% of the CF-causing mutations can now be detected in the South African white population. Haplotype analysis suggests a founder effect in South Africans of European origin for the two common CFTR mutations, 3272-26A-->G and 394delTT. The diagnosis of CF has been confirmed in 14 coloured and 12 black CF patients. In the coloured population, both the deltaF508 and 3120 + 1G-->A mutations occur at appreciable frequencies of 43 and 29%, respectively. In the black population, the most common CF-causing mutation, the 3120 + 1G-->A mutation, occurs at an estimated frequency of 46%. Four other mutations have been detected, resulting in the identification of a total of 62.5% of mutations in this population.

Buried charged surface in proteins

BACKGROUND

The traditional picture of charged amino acids in globular proteins is that they are almost exclusively on the outside exposed to the solvent. Buried charges, when they do occur, are assumed to play an essential role in catalysis and ligand binding, or in stabilizing structure as, for instance, helix caps.

RESULTS

By analyzing the amount and distribution of buried charged surface and charges in proteins over a broad range of protein sizes, we show that buried charge is much more common than is generally believed. We also show that the amount of buried charge rises with protein size in a manner which differs from other types of surfaces, especially aromatic and polar uncharged surfaces. In large proteins such as hemocyanin, 35% of all charges are greater than 75% buried. Furthermore, at all sizes few charged groups are fully exposed. As an experimental test, we show that replacement of the buried D178 of muconate lactonizing enzyme by N stabilizes the enzyme by 4.2 degrees C without any change in crystallographic structure. In addition, free energy calculations of stability support the experimental results.

CONCLUSIONS

Nature may use charge burial to reduce protein stability; not all buried charges are fully stabilized by a prearranged protein environment. Consistent with this view, thermophilic proteins often have less buried charge. Modifying the amount of buried charge at carefully chosen sites may thus provide a general route for changing the thermophilicity or psychrophilicity of proteins.

Catalytically important ionizations along the reaction pathway of yeast pyrophosphatase

Five catalytic functions of yeast inorganic pyrophosphatase were measured over wide pH ranges: steady-state PP(i) hydrolysis (pH 4. 8-10) and synthesis (6.3-9.3), phosphate-water oxygen exchange (pH 4. 8-9.3), equilibrium formation of enzyme-bound PP(i) (pH 4.8-9.3), and Mg(2+) binding (pH 5.5-9.3). These data confirmed that enzyme-PP(i) intermediate undergoes isomerization in the reaction cycle and allowed estimation of the microscopic rate constant for chemical bond breakage and the macroscopic rate constant for PP(i) release. The isomerization was found to decrease the pK(a) of the essential group in the enzyme-PP(i) intermediate, presumably nucleophilic water, from >7 to 5.85. Protonation of the isomerized enzyme-PP(i) intermediate decelerates PP(i) hydrolysis but accelerates PP(i) release by affecting the back isomerization. The binding of two Mg(2+) ions to free enzyme requires about five basic groups with a mean pK(a) of 6.3. An acidic group with a pK(a) approximately 9 is modulatory in PP(i) hydrolysis and metal ion binding, suggesting that this group maintains overall enzyme structure rather than being directly involved in catalysis.

Treatment of axillary and palmar hyperhidrosis with botulinum toxin

The author presents his experience with hyperhidrosis treatment using type-A botulinum toxin. The drug was applied on axillary, palmar, plantar, facial, inguinal, and gluteus areas for a 36-month period. The effect achieved-sweating decrease-was observed in 100% of the patients for a variable period ranging from 5 to 14 months. There was a slight decrease in hand muscle strength in some cases, which was spontaneously recovered after 2 weeks.

New High-Resolution Analysis of the 3nu(3) and 2nu(1) + nu(3) Bands of Nitrogen Dioxide (NO(2)) by Fourier Transform Spectroscopy

Using new high-resolution Fourier transform spectra recorded at the University of Denver in the 2-µm region, a new and more extended analysis of the 2nu(1) + nu(3) and 3nu(3) bands of nitrogen dioxide, located at 4179.9374 and 4754.2039 cm(-1), respectively, has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model that takes into account both the Coriolis interactions between the spin-rotation energy levels of the (201) vibrational "bright" state with those of the (220) "dark" state. The interactions between the (003) bright state with the (022) dark state were similarly treated. The spin-rotation resonances within each of the NO(2) vibrational states were also taken into account. The precise vibrational energies and the rotational, spin-rotational, and coupling constants were obtained for the two dyads {(220), (201)} and {(022), (003)} of the (14)N(16)O(2) interacting states. From the experimental line intensities of the 2nu(1) + nu(3) and 3nu(3) bands, a determination of their vibrational transition moment constants was performed. A comprehensive list of line positions and line intensities of the {2nu(1) + 2nu(2), 2nu(1) + nu(3)} and the {2nu(2) + 2nu(3), 3nu(3)} interacting bands of (14)N(16)O(2) was generated. In addition, assuming the harmonic approximation and using the Hamiltonian constants derived in this work and in previous studies (A. Perrin, J.-M. Flaud, A. Goldman, C. Camy-Peyret, W. J. Lafferty, Ph. Arcas, and C. P. Rinsland, J. Quant. Spectrosc. Radiat. Transfer 60, 839-850 (1998)), we have generated synthetic spectra for the {(022), (003)}-{(040), (021), (002)} hot bands at 6.3 µm and for the {(220), (201)}-{(100), (020), (001)} hot bands at 3.5 µm, which are in good agreement with the observed spectra. Copyright 2000 Academic Press.

Resistance of very young mice to inhaled allergen sensitization is overcome by coexposure to an air-pollutant aerosol

The role of air pollution in the initiation of asthma is controversial. We sought to model the potential effects of air pollution on immune responses to inhaled allergens in developing lungs by using very young mice. Neonatal mice were repeatedly exposed to aerosolized ovalbumin (OVA; 3% in phosphate-buffered saline for 10 min/d, from Days 5 to 15 of age). Some mice were also exposed to leachate of residual oil fly ash (ROFA-s), a surrogate for ambient air particles, for 30 min, on Days 6, 8, and 10 of age). Repeated exposure of very young mice to allergen alone (OVA) or pollutant alone (ROFA-s) had no effect on airway hyperresponsiveness (AHR, measured as enhanced pause (Penh) with noninvasive plethysmography at Day 16 of age), and did not cause inflammation or OVA-specific antibody production. Similar exposures of adult mice to either OVA alone or to OVA + ROFA-s did result in AHR, without evidence of enhancement by combined exposure. In contrast, very young mice exposed to both OVA and ROFA-s showed significantly increased AHR (e.g., Penh with 50 mg/ml methacholine for OVA + ROFA-s versus OVA alone = 2.6 +/- 0.4 [mean +/- SE], versus 1.2 +/- 0.1; p < 0.01, n >/= 15), and produced OVA-specific IgE and IgG upon allergen challenge a week later. Immunostaining of airways taken from mice at Day 11 showed a marked increase in Ia(+) cells after OVA + ROFA-s exposure. We conclude that exposure to pollutant aerosols can disrupt normal resistance to sensitization to inhaled allergens, and can thereby promote development of airway hypersensitivity in this neonatal/juvenile mouse model.

Evidence that a dodecamer duplication in the gene HOPA in Xq13 is not associated with mental retardation

A recent study suggested that a dodecamer duplication in exon 42 of the HOPA gene in Xq13 may be a significant factor in the etiology of X-linked mental retardation. In an effort to investigate this possibility, we determined the incidence of the dodecamer duplication in cohorts of non-fragile X males with mental retardation from three countries, cohorts of fragile X males from two countries, 43 probands from families with X-linked mental retardation and control cohorts from three countries. The duplication was found in 3.6-4.0% of male patients from two non-fragile X groups (Italy and South Carolina), in 1.2% from another non-fragile X group (South Africa), but in no male patients from families with X-linked mental retardation (South Carolina). The dodecamer duplication was also found in several white males with fragile X syndrome from France (5%) and South Africa (22.2%). Additionally, the duplication was found in 1.5% of South Carolinian newborn males, 2.5% South Carolinian male college students, 5% Italian male controls and 4.5% of the white South African controls. None of the black South African non-fragile X individuals with mental retardation, the fragile X or the control samples tested carried the duplication, suggesting that the duplication is rare in the black South African population. The incidence of the duplication was not significantly different between any of the groups in the study. Therefore, results of our studies in four different populations do not corroborate the findings of the previous study, and indicate that the HOPA dodecamer duplication does not convey an increased susceptibility to mental retardation.

Reciprocal effects of substitutions at the subunit interfaces in hexameric pyrophosphatase of Escherichia coli. Dimeric and monomeric forms of the enzyme

A homohexameric molecule of Escherichia coli pyrophosphatase is arranged as a dimer of trimers, with an active site present in each of its six monomers. Earlier we reported that substitution of His(136) and His(140) in the intertrimeric subunit interface splits the molecule into active trimers (Velichko, I. S., Mikalahti, K., Kasho, V. N., Dudarenkov, V. Y., Hyytiä, T., Goldman, A., Cooperman, B. S., Lahti, R., and Baykov, A. A. (1998) Biochemistry 37, 734-740). Here we demonstrate that additional substitutions of Tyr(77) and Gln(80) in the intratrimeric interface give rise to moderately active dimers or virtually inactive monomers, depending on pH, temperature, and Mg(2+) concentration. Successive dissociation of the hexamer into trimers, dimers, and monomers progressively decreases the catalytic efficiency (by 10(6)-fold in total), and conversion of a trimer into dimer decreases the affinity of one of the essential Mg(2+)-binding sites/monomer. Disruptive substitutions predominantly in the intratrimeric interface stabilize the intertrimeric interface and vice versa, suggesting that the optimal intratrimeric interaction is not compatible with the optimal intertrimeric interaction. Because of the resulting "conformational strain," hexameric wild-type structure appears to be preformed to bind substrate. A hexameric triple variant substituted at Tyr(77), Gln(80), and His(136) exhibits positive cooperativity in catalysis, consistent with this model.

Ascites and pleural effusion secondary to extramedullary hematopoiesis

Extramedullary hematopoiesis in the pleura and peritoneum is rare. It is usually asymptomatic and generally is diagnosed on post mortem examination. Herein we describe a 33-year-old woman with long-standing myelofibrosis who presented with symptomatic ascites and pleural effusion. After complete evaluation, these were found to have been caused by extramedullary hematopoietic implants to the pleura and peritoneum. The pleural effusion responded to low-dose radiotherapy.

Pyruvate formate lyase is structurally homologous to type I ribonucleotide reductase

BACKGROUND

Pyruvate formate lyase (PFL) catalyses a key step in Escherichia coli anaerobic glycolysis by converting pyruvate and CoA to formate and acetylCoA. The PFL mechanism involves an unusual radical cleavage of pyruvate, involving an essential C alpha radical of Gly734 and two cysteine residues, Cys418 and Cys419, which may form thiyl radicals required for catalysis. We undertook this study to understand the structural basis for catalysis.

RESULTS

The first structure of a fragment of PFL (residues 1-624) at 2.8 A resolution shows an unusual barrel-like structure, with a catalytic beta finger carrying Cys418 and Cys419 inserted into the centre of the barrel. Several residues near the active-site cysteines can be ascribed roles in the catalytic mechanism: Arg176 and Arg435 are positioned near Cys419 and may bind pyruvate/formate and Trp333 partially buries Cys418. Both cysteine residues are accessible to each other owing to their cis relationship at the tip of the beta finger. Finally, two clefts that may serve as binding sites for CoA and pyruvate have been identified.

CONCLUSIONS

PFL has striking structural homology to the aerobic ribonucleotide reductase (RNR): the superposition of PFL and RNR includes eight of the ten strands in the unusual RNR alpha/beta barrel as well as the beta finger, which carries key catalytic residues in both enzymes. This provides the first structural proof that RNRs and PFLs are related by divergent evolution from a common ancestor.

Evolutionary aspects of inorganic pyrophosphatase

Based on the primary structure, soluble inorganic pyrophosphatases can be divided into two families which exhibit no sequence similarity to each other. Family I, comprising most of the known pyrophosphatase sequences, can be further divided into prokaryotic, plant and animal/fungal pyrophosphatases. Interestingly, plant pyrophosphatases bear a closer similarity to prokaryotic than to animal/fungal pyrophosphatases. Only 17 residues are conserved in all 37 pyrophosphatases of family I and remarkably, 15 of these residues are located at the active site. Subunit interface residues are conserved in animal/fungal but not in prokaryotic pyrophosphatases.

Population pharmacokinetics of oral morphine and its glucuronides in children receiving morphine as immediate-release liquid or sustained-release tablets for cancer pain

OBJECTIVES

(1) To determine the pharmacokinetics of morphine, morphine-6-glucuronide (M6G), and morphine-3-glucuronide (M3G) in children with cancer receiving morphine as immediate-release morphine liquid or sustained-release tablets. (2) To determine differences with age within the group and from adults. (3) To explore relationships between plasma concentration and pain measurements.

STUDY DESIGN

Blood samples were collected and plasma analyzed by high-performance liquid chromatography with electrochemical and fluorescence detection. Population pharmacokinetic parameters were derived with the program P-PHARM.

RESULTS

Forty children with a median age of 11.4 years (range 1.7 to 18.7 years) received a median dose of 1.4 mg/kg/d (range 0.4 to 24.6 mg/kg/d). A median of 4 blood samples per child was collected. Plasma clearance of morphine was 23.1 mL/min per kg body weight. The volume of distribution was 5.2 L/kg. Molar ratios of M3G/morphine, M6G/morphine, and M3G/M6G were 21.1, 4.7, and 4.2, respectively. Children <11 years had significantly higher clearance and larger volume of distribution for morphine and its glucuronides than older children and adults. Regression analysis indicated average plasma morphine concentration equal to dose (mg/kg/d) x 8.6 (95% confidence interval 7.4 to 9.9). Significant pain was present in 30% of the children. Higher pain scores were recorded in children with average morphine concentrations <12 ng/mL (P <.01 MW).

CONCLUSION

Age differences in morphine pharmacokinetics exist within children and compared with adults. The study supports a starting dose of 1.5 to 2. 0 mg/kg/d to provide plasma morphine concentrations >12 ng/mL in children with cancer pain unrelieved by mild to moderate strength analgesia.

Of barn owls and bankers: a lush variety of alpha/beta hydrolases

alpha/beta Hydrolase fold proteins are an important, diverse, widespread group of enzymes not yet fully exploited by structural biologists. We describe the current state of knowledge of this family, and suggest a smaller definition of the required core and some possible future avenues of exploration.

Sulfolobus acidocaldarius inorganic pyrophosphatase: structure, thermostability, and effect of metal ion in an archael pyrophosphatase

The first crystal structure of an inorganic pyrophosphatase (S-PPase) from an archaebacterium, the thermophile Sulfolobus acidocaldarius, has been solved by molecular replacement and refined to an R-factor of 19.7% at 2.7 A. S-PPase is a D3 homohexameric protein with one Mg2+ per active site in a position similar to, but not identical with, the first activating metal in mesophilic pyrophosphatases (PPase). In mesophilic PPases, Asp65, Asp70, and Asp102 coordinate the Mg2+, while only Asp65 and Asp102 do in S-PPase, and the Mg2+ moves by 0.7 A. S-PPase may therefore be deactivated at low temperature by mispositioning a key metal ion. The monomer S-PPase structure is very similar to that of Thermus thermophilus (T-PPase) and Escherichia coli (E-PPase), root-mean-square deviations around 1 A/Calpha. But the hexamer structures of S- and T-PPase are more tightly packed and more similar to each other than they are to that of E-PPase, as shown by the increase in surface area buried upon oligomerization. In T-PPase, Arg116 creates an interlocking ionic network to both twofold and threefold related monomers; S-PPase has hydrophilic interactions to threefold related monomers absent in both E- and T-PPase. In addition, the thermostable PPases have about 7% more hydrogen bonds per monomer than E-PPase, and, especially in S-PPase, additional ionic interactions anchor the C-terminus to the rest of the protein. Thermostability in PPases is thus due to subtle improvements in both monomer and oligomer interactions.

Functional characterization of Escherichia coli inorganic pyrophosphatase in zwitterionic buffers

Catalysis by Escherichia coli inorganic pyrophosphatase (E-PPase) was found to be strongly modulated by Tris and similar aminoalcoholic buffers used in previous studies of this enzyme. By measuring ligand-binding and catalytic properties of E-PPase in zwitterionic buffers, we found that the previous data markedly underestimate Mg(2+)-binding affinity for two of the three sites present in E-PPase (3.5- to 16-fold) and the rate constant for substrate (dimagnesium pyrophosphate) binding to monomagnesium enzyme (20- to 40-fold). By contrast, Mg(2+)-binding and substrate conversion in the enzyme-substrate complex are unaffected by buffer. These data indicate that E-PPase requires in total only three Mg2+ ions per active site for best performance, rather than four, as previously believed. As measured by equilibrium dialysis, Mg2+ binds to 2.5 sites per monomer, supporting the notion that one of the tightly binding sites is located at the trimer-trimer interface. Mg2+ binding to the subunit interface site results in increased hexamer stability with only minor consequences for catalytic activity measured in the zwitterionic buffers, whereas Mg2+ binding to this site accelerates substrate binding up to 16-fold in the presence of Tris. Structural considerations favor the notion that the aminoalcohols bind to the E-PPase active site.