De novo adamantinomatous craniopharyngioma with long-term pre-diagnostic imaging.

Adamantinomatous craniopharyngioma has a bimodal age distribution occurring in children aged 5-15 years and less frequently in adults aged 45-60 years. The current embryogenetic hypothesis suggests that adamantinomatous craniopharyngioma (ACP) arises from epithelial remnants of the craniopharyngeal duct or Rathke's pouch. It is thought that this tumor exists early on during childhood but remains indolent, growing very slowly until it is diagnosed incidentally or due to symptoms. Recent reports of de novo development of ACP, however, have challenged this theory. Herein, we present a case of an incidentally discovered de novo adamantinomatous craniopharyngioma that was documented to arise de novo on serial MRIs performed for a different indication. To our knowledge, this is the first report of a middle-aged patient who is diagnosed with a de novo ACP documented with contrast-enhanced MRIs of the sella over a 16-year period. This case challenges our current understanding of the pathophysiology of adamantinomatous craniopharyngioma.

Exhaustive matching of the entire protein sequence database.

The entire protein sequence database has been exhaustively matched. Definitive mutation matrices and models for scoring gaps were obtained from the matching and used to organize the sequence database as sets of evolutionarily connected components. The methods developed are general and can be used to manage sequence data generated by major genome sequencing projects. The alignments made possible by the exhaustive matching are the starting point for successful de novo prediction of the folded structures of proteins, for reconstructing sequences of ancient proteins and metabolisms in ancient organisms, and for obtaining new perspectives in structural biochemistry.

Spatial adaptation of short-wavelength pathways in humans.

Color-selective spatial adaptation of the short-wavelength, or blue-sensitive, pathway was demonstrated. The adaptation was orientation selective and strongly monocular. Adaptation was assessed by measuring visibility thresholds for monochromatic gratings in subjects adapted to high-contrast violet gratings designed to stimulate only blue-sensitive cones. The results showed spatially selective, adaptable channels within the short-wavelength pathway.

Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States.

OBJECTIVES: To evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers' compensation claims for hearing loss. METHODS: Washington State workers' compensation records were used to identify up to 10 companies in each of eight industries. Each company (n = 76) was evaluated by a management interview, employee personal noise dosimetry (n = 983), and employee interviews (n = 1557). RESULTS: Full-shift average exposures were > or =85 dBA for 50% of monitored employees, using Occupational Safety and Health Administration (OSHA) parameters with a 5 dB exchange rate (L(ave)), but 74% were > or =85 dBA using a 3 dB exchange rate (L(eq)). Only 14% had L(ave) > or =90 dBA, but 42% had L(eq) > or =90 dBA. Most companies conducted noise measurements, but most kept no records, and consideration of noise controls was low in all industries. Hearing loss prevention programmes were commonly incomplete. Management interview scores (higher score = more complete programme) showed significant associations with percentage of employees having L(ave) > or =85 dBA and presence of a union (multiple linear regression; R2 = 0.24). Overall, 62% of interviewed employees reported always using hearing protection when exposed. Protector use showed significant associations with percentage of employees specifically required to use protection, management score, and average employee time spent > or =95 dBA (R2 = 0.65). CONCLUSIONS: The findings raise serious concerns about the adequacy of prevention, regulation, and enforcement strategies in the United States. The percentage of workers with excessive exposure was 1.5-3 times higher using a 3 dB exchange rate instead of the OSHA specified 5 dB exchange rate. Most companies gave limited or no attention to noise controls and relied primarily on hearing protection to prevent hearing loss; yet 38% of employees did not use protectors routinely. Protector use was highest when hearing loss prevention programmes were most complete, indicating that under-use of protection was, in some substantial part, attributable to incomplete or inadequate company efforts.

Ghrelin causes hyperphagia and obesity in rats.

Ghrelin, a circulating growth hormone-releasing peptide derived from the stomach, stimulates food intake. The lowest systemically effective orexigenic dose of ghrelin was investigated and the resulting plasma ghrelin concentration was compared with that during fasting. The lowest dose of ghrelin that produced a significant stimulation of feeding after intraperitoneal injection was 1 nmol. The plasma ghrelin concentration after intraperitoneal injection of 1 nmol of ghrelin (2.83 +/- 0.13 pmol/ml at 60 min postinjection) was not significantly different from that occurring after a 24-h fast (2.79 +/- 0.32 pmol/ml). After microinjection into defined hypothalamic sites, ghrelin (30 pmol) stimulated food intake most markedly in the arcuate nucleus (Arc) (0-1 h food intake, 427 +/- 43% of control; P < 0.001 vs. control, P < 0.01 vs. all other nuclei), which is potentially accessible to the circulation. After chronic systemic or intracerebroventricular (ICV) administration of ghrelin for 7 days, cumulative food intake was increased (intraperitoneal ghrelin 13.6 +/- 3.4 g greater than saline-treated, P < 0.01; ICV ghrelin 19.6 +/- 5.5 g greater than saline-treated, P < 0.05). This was associated with excess weight gain (intraperitoneal ghrelin 21.7 +/- 1.4 g vs. saline 10.6 +/- 1.9 g, P < 0.001; ICV ghrelin 15.3 +/- 4.3 g vs. saline 2.2 +/- 3.8 g, P < 0.05) and adiposity. These data provide evidence that ghrelin is important in long-term control of food intake and body weight and that circulating ghrelin at fasting concentrations may stimulate food intake.

K(+)- and HCO3(-)-dependent acid-base transport in squid giant axons. I. Base efflux.

We used microelectrodes to monitor the recovery (i.e., decrease) of intracellular pH (pHi) after using internal dialysis to load squid giant axons with alkali to pHi values of 7.7, 8.0, or 8.3. The dialysis fluid (DF) contained 400 mM K+ but was free of Na+ and Cl-. The artificial seawater (ASW) lacked Na+, K+, and Cl-, thereby eliminating effects of known acid-base transporters on pHi. Under these conditions, halting dialysis unmasked a slow pHi decrease caused at least in part by acid-base transport we refer to as "base efflux." Replacing K+ in the DF with either NMDG+ or TEA+ significantly reduced base efflux and made membrane voltage (Vm) more positive. Base efflux in K(+)-dialyzed axons was stimulated by decreasing the pH of the ASW (pHo) from 8 to 7, implicating transport of acid or base. Although postdialysis acidifications also occurred in axons in which we replaced the K+ in the DF with Li+, Na+, Rb+, or Cs+, only with Rb+ was base efflux stimulated by low pHo. Thus, the base effluxes supported by K+ and Rb+ appear to be unrelated mechanistically to those observed with Li+, Na+, or Cs+. The combination of 437 mM K+ and 12 mM HCO3- in the ASW, which eliminates the gradient favoring a hypothetical K+/HCO3- efflux, blocked pHi recovery in K(+)-dialyzed axons. However, the pHi recovery was not blocked by the combination of 437 mM Na+, veratridine, and CO2/HCO3- in the ASW, a treatment that inverts electrochemical gradients for H+ and HCO3- and would favor passive H+ and HCO3- fluxes that would have alkalinized the axon. Similarly, the recovery was not blocked by K+ alone or HCO3- alone in the ASW, nor was it inhibited by the K-H pump blocker Sch28080 nor by the Na-H exchange inhibitors amiloride and hexamethyleneamiloride. Our data suggest that a major component of base efflux in alkali-loaded axons cannot be explained by metabolism, a H+ or HCO3- conductance, or by a K-H exchanger. However, this component could be mediated by a novel K/HCO3- cotransporter.

K(+)- and HCO3(-)-dependent acid-base transport in squid giant axons II. Base influx.

We used microelectrodes to determine whether the K/HCO3 cotransporter tentatively identified in the accompanying paper (Hogan, E. M., M. A. Cohen, and W. F. Boron. 1995. Journal of General Physiology. 106:821-844) can mediate an increase in the intracellular pH (pHi) of squid giant axons. An 80-min period of internal dialysis increased pHi to 7.7, 8.0, or 8.3; the dialysis fluid was free of K+, Na+, and Cl-. Our standard artificial seawater (ASW), which also lacked Na+, K+, and Cl-, had a pH of 8.0. Halting dialysis unmasked a slow pHi decrease. Subsequently introducing an ASW containing 437 mM K+ and 0.5% CO2/12 mM HCO3- had two effects: (a) it caused membrane potential (Vm) to become very positive, and (b) it caused a rapid pHi decrease, because of CO2 influx, followed by a slower plateau-phase pHi increase, presumably because of inward cotransport of K+ and HCO3- ("base influx"). Only extracellular Rb+ substituted for K+ in producing the plateau-phase pHi increase in the presence of CO2/HCO3-. Mean fluxes with Na+, Li+, and Cs+ were not significantly different from zero, even though Vm shifts were comparable for all monovalent cations tested. Thus, unless K+ or Rb+ (but not Na+, Li+, or Cs+) somehow activates a conductive pathway for H+, HCO3-, or both, it is unlikely that passive transport of H+, HCO3-, or both makes the major contribution to the pHi increase in the presence of K+ (or Rb+) and CO2/HCO3-. Because exposing axons to an ASW containing 437 mM K+, but no CO2/HCO3-, produced at most a slow pHi increase, K-H exchange could not make a major contribution to base influx. Introducing an ASW containing CO2/HCO3-, but no K+ also failed to elicit base influx. Because we observed base influx when the ASW and DF were free of Na+ and Cl-, and because the disulfonic stilbene derivatives SITS and DIDS failed to block base influx, Na(+)-dependent Cl-HCO3 exchange also cannot account for the results. Rather, we suggest that the most straightforward explanation for the pHi increase we observed in the simultaneous presence of K+ and CO2/HCO3- is the coupled uptake of K+ and HCO3-.

Predicted secondary structure for the Src homology 3 domain.

A de novo secondary structure prediction has been prepared for Src homology domain 3, in advance of any crystallographic information concerning any member of this interesting protein family. The prediction can be compared with a crystal structure that will be published in Nature on October 29, 1992. The prediction is based on analysis of a multiple alignment of homologous proteins. The patterns of variation and conservation of amino acids across the alignment allow the determination of surface and internal positions, which then allow the assignment of secondary structure. The prediction is quite different both in method and, in this case, result from predictions based on propensities (e.g. Garnier-Osgurthorpe-Robson) of particular amino acids to appear in particular types of secondary structure.

Bona fide prediction of aspects of protein conformation. Assigning interior and surface residues from patterns of variation and conservation in homologous protein sequences.

Heuristics have been developed for analyzing patterns of conservation and variation within a set of aligned homologous protein sequences for the purpose of assigning amino acids whose side-chains lie on the surface and inside the folded structure of a protein. These were used in several recent bona fide predictions of the secondary structure of proteins from sequence data, made and published before crystallographic information became available. Heuristics based on concurrent hydrophilic variation identify positions that lie on the surface. Heuristics based on concurrent hydrophobic conservation and variation identify positions lying in the interior. These heuristics are described here in detail and their performance evaluated when applied to seven protein families with known three-dimensional structures. The performance of individual heuristics is shown to depend on the nature of the multiple alignment within the protein family, and a strategy is presented for obtaining surface and interior assignments useful for predicting secondary structure.

Empirical and structural models for insertions and deletions in the divergent evolution of proteins.

The exhaustive matching of the protein sequence database makes possible a broadly based study of insertions and deletions (indels) during divergent evolution. In this study, the probability of a gap in an alignment of a pair of homologous protein sequences was found to increase with the evolutionary distance measured in PAM units (number of accepted point mutations per 100 amino acid residues). A relationship between the average number of amino acid residues between indels and evolutionary distance suggests that a unit 30 to 40 amino acid residues in length remains, on average, undisrupted by indels during divergent evolution. Further, the probability of a gap was found to be inversely proportional to gap length raised to the 1.7 power. This empirical law fits closely over the entire range of gap lengths examined. Gap length distribution is largely independent of evolutionary distance. These results rule out the widely used linear gap penalty as a satisfactory formula for scoring gaps when constructing alignments. Further, the observed gap length distribution can be explained by a simple model of selective pressures governing the acceptance of indels during divergent evolution. Finally, this model provides theoretical support for using indels as part of "parsing algorithms", important in the de novo prediction of the folded structure of proteins from the sequence data.

The role of essential pyrimidines in the hairpin ribozyme-catalysed reaction.

The hairpin ribozyme is an example of a small catalytic RNA that catalyses the endonucleolytic transesterification of RNA in a highly sequence-specific manner. We have utilised chemical synthesis of RNA to create mutants of the hairpin ribozyme in which a nucleoside analogue replaces one of the essential pyrimidines in the ribozyme. Individual pyrimidine nucleosides were substituted by 4-thiouridine, O4-methyluridine, O2-methyluridine or 2-pyrimidinone-1-beta-d-riboside. To facilitate the synthesis of oligoribonucleotides containing 4-thiouridine, we have devised a new synthetic route to the key intermediate 5'-O-(4, 4'-dimethoxytrityl)-2'-O-tert-butyldimethylsilyl-S-cyanoethyl-4-thiou ridine. The ability of the modified ribozymes to support catalysis was studied and the steady-state kinetic parameters were determined for each mutant. The range of analogues used in this study allows the important functional groups of the essential pyrimidines to be identified. The results demonstrate that each pyrimidine (U41, U42 and C25) plays an important role in hairpin ribozyme catalysis. The findings are discussed in terms of the various models that have been proposed for loop B of the hairpin ribozyme.

Ghrelin enhances appetite and increases food intake in humans.

Ghrelin is a recently identified endogenous ligand for the growth hormone secretagogue receptor. It is synthesized predominantly in the stomach and found in the circulation of healthy humans. Ghrelin has been shown to promote increased food intake, weight gain and adiposity in rodents. The effect of ghrelin on appetite and food intake in man has not been determined. We investigated the effects of intravenous ghrelin (5.0 pmol/kg/min) or saline infusion on appetite and food intake in a randomised double-blind cross-over study in nine healthy volunteers. There was a clear-cut increase in energy consumed by every individual from a free-choice buffet (mean increase 28 +/- 3.9%, p<0.001) during ghrelin compared with saline infusion. Visual analogue scores for appetite were greater during ghrelin compared to saline infusion. Ghrelin had no effect on gastric emptying as assessed by the paracetamol absorption test. Ghrelin is the first circulating hormone demonstrated to stimulate food intake in man. Endogenous ghrelin is a potentially important new regulator of the complex systems controlling food intake and body weight.

Pancreatic polypeptide reduces appetite and food intake in humans.

Pancreatic polypeptide (PP) is a gut hormone released from the pancreas in response to ingestion of food. Plasma PP has been shown to be reduced in conditions associated with increased food intake and elevated in anorexia nervosa. In addition peripheral administration of PP has been shown to decrease food intake in rodents. These findings suggest that PP may act as a circulating factor that regulates food intake. Therefore we investigated the effect of intravenous infusion of PP (10 pmol/kg/min) on appetite and food intake in a randomised double-blind placebo-controlled crossover study in ten healthy volunteers. Infusion of PP reduced appetite and decreased the energy intake at a buffet lunch two hours post-infusion by 21.8 +/- 5.7% (P < 0.01). More importantly the inhibition of food intake was sustained, such that energy intake, as assessed by food diaries, was significantly reduced both the evening of the study and the following morning. Overall PP infusion reduced cumulative 24-hour energy intake by 25.3 +/- 5.8%. In conclusion our data demonstrates that PP causes a sustained decrease in both appetite and food intake.

Fluoroquinolones: relationships between structural variations, mammalian cell cytotoxicity, and antimicrobial activity.

Fluoroquinolones are potent inhibitors of bacterial topoisomerase II (DNA gyrase). They can also inhibit eukaryotic topoisomerases, which could possibly lead to clastogenicity and/or cellular toxicity. Recent studies have demonstrated a correlation between mammalian cell cytotoxicity of the fluoroquinolones and the potential of these compounds to induce micronuclei, a genetic toxicity endpoint. In an effort to identify potent nontoxic quinolone antibacterials, we have examined the structural features of the fluoroquinolones associated with mammalian cell cytotoxicity. An investigation of a wide variety of substituents at the 1, 5, 7, and 8 positions of a quinolone nucleus was conducted. The results indicate that no one position has a controlling effect on the observed cytotoxicity. Instead, a combination of the various substituents contributes to the effects seen. Certain trends were apparent, such as the fact that compounds with pyrrolidines at the R-7 position were more cytotoxic than those with piperazines, and halogens at R-8 (X-position) were associated with more cytotoxicity relative to hydrogen. A general trend also existed between the cytotoxicity of the compounds and their Gram-positive antibacterial activity. A detailed comparison between the various groups and positional variations as they controlled the cytotoxicity and antibacterial activity is presented.

The synthesis, structure-activity, and structure-side effect relationships of a series of 8-alkoxy- and 5-amino-8-alkoxyquinolone antibacterial agents.

A series of 1-cyclopropyl-6-fluoro-8-alkoxy (8-methyoxy and 8-ethoxy)-quionoline-3-carboxylic acids and 1-cyclopropyl-5-amino-6-fluoro-8-alkoxyquinoline-3-carboxylic acids has been prepared and evaluated for antibacterial activity. In addition, they were also compared to quinolones with classic substitution at C8 (H, F, Cl) and the naphthyridine nucleus in a phototoxicity and mammalian cell cytotoxicity assay. The series of 8-methoxyquinolones had antibacterial activity against Gram-positive, Gram-negative, and anaerobic bacteria equivalent to the most active 8-substituted compounds (8-F and 8-Cl). There was also a concomitant reduction in several of the potential side effects (i.e., phototoxicity and clonogenicity) compared to the most active quinolones with classic substitution at C-8. The 8-ethoxy derivatives had an even better safety profile but were significantly less active (2-3 dilutions) in the antibacterial assay.

Utilizing routine sonohysterography to detect intrauterine pathology before initiating hormone replacement therapy.

OBJECTIVE: To assess the utility of performing routine sonohysterography in conjunction with endometrial thickness measurement for detecting intrauterine pathology in asymptomatic postmenopausal women. DESIGN: Asymptomatic postmenopausal women (n = 60, mean age 52.7 +/- 4.5 years, amenorrhea > or = 6 months, follicle stimulating hormone > or = 40 mIU/mL) were evaluated with sonohysterography followed by endometrial biopsy before initiating hormone replacement therapy. RESULTS: Hyperplasia was detected in 5 of 22 (22.7%) patients with endometrial thickness of > 5 mm and in 0 of 38 (0.0%) patients with endometrial thickness of < or = 5 mm. When sonohysterography was performed, intracavitary pathology was discovered in 14 of 38 (36.8%) patients with endometrial thickness of < or = 5 mm (10 polyps, three submucosal myomas, and one septate uterus) and 14 of 22 (63.6%) patients with endometrial thickness of > 5 mm (nine polyps, four submucosal myomas, and one Asherman's syndrome). CONCLUSIONS: Endometrial thickness of < or = 5 mm excludes hyperplasia but does not eliminate other intrauterine pathology that may be discovered by sonohysterography.

Treatment of experimental Pseudomonas corneal ulcers with enoxacin, a quinolone antibiotic.

Enoxacin is a broad-spectrum quinolone-derivative antibiotic. In a rabbit model of keratitis caused by a Pseudomonas species, enoxacin (3 mg/mL) was as effective as gentamicin sulfate (3 mg/mL) and enoxacin (10 mg/mL) in reducing viable bacterial counts in corneas after 24 hours of hourly therapy with eye drops. Bacterial counts were reduced by about 5000-fold by enoxacin treatment when compared with placebo-treated controls. Penetration studies of topical enoxacin (3 mg/mL) showed that concentrations in cornea and aqueous humor reached levels above reported minimal inhibitory concentrations when an epithelial defect was present. Further investigation of enoxacin for treatment of ocular disease is warranted.

Dissemination of HIV: how serious is it for women, medically and psychologically?

PIP: In the US, women comprise the population group with the most rapidly increasing rate of human immunodeficiency virus (HIV) infection, yet these women--predominantly poor and Black or Hispanic--must face the added trauma of discrimination in the health care system. Even the clinical case definition of acquired immunodeficiency syndrome (AIDS) fails to include recurrent pelvic inflammatory disease, recurrent vulvovaginal candidiasis, and cervical carcinoma in situ, thereby excluding thousands of women from AIDS-related entitlements. Essential for HIV-infected women is empowerment to facilitate sound decision making about choice of partners, barrier contraception, pregnancy, abortion, and breast feeding. The vast majority of women with sex partners in high-risk groups do not use condoms, in part because of fear of loss of the relationship or withdrawal of financial support. HIV-positive women are especially in need of condom use to prevent further transmission and unwanted pregnancy. Pregnancy in HIV-positive women is associated with a 30% chance that the infant will acquire the infection and alarming increases in the ranks of the 20,000 US children already orphaned by AIDS. Nonetheless, the right of HIV-infected women to bear children should be protected, and these women should be given the option of artificial insemination of washed semen and Cesarean section delivery to reduce the risk of transmission to partner and child. Finally, because substance abusing women are not always able to make appropriate decisions about their sexual practices, drug treatment on demand and comprehensive outreach programs for HIV-infected women at shelters, the streets, and shooting galleries must be implemented.^ieng

Activity of clinafloxacin, trovafloxacin, quinupristin/dalfopristin, and other antimicrobial agents versus Staphylococcus aureus isolates with reduced susceptibility to vancomycin.

Isolations of Staphylococcus aureus strains with reduced susceptibility to vancomycin are now being reported worldwide. In testing here by broth microdilution according to NCCLS guidelines and applying vancomycin breakpoint criteria (susceptible at 4 micrograms/mL), two of three strains were susceptible (MICs at 4 micrograms/mL) rather than intermediate (MICs at 8 micrograms/mL) as previously reported by other laboratories. Clinafloxacin was more active (MICs/MBCs at 0.5 to 2 micrograms/mL) than ciprofloxacin, grepafloxacin, levofloxacin, ofloxacin, and sparfloxacin. Trovafloxacin, trimethoprim/sulfamethoxazole, and quinupristin/dalfopristin were the next most active agents, although quinupristin/dalfopristin was bactericidal against only two of these three strains. Amikacin, imipenem, oxacillin, and rifampin were less active.