Regulation of glucose transporters GLUT-4 and GLUT-1 gene transcription in denervated skeletal muscle

Because GLUT-4 expression is decreased whereas GLUT-1 expression is increased in denervated skeletal muscle, we examined the effects of denervation on GLUT-4 and GLUT-1 gene transcription. The right hindlimb skeletal muscle of male transgenic mice containing sequential truncations (2,400, 1,639, 1,154, and 730 bp) of the human GLUT-4 promoter linked to the chloramphenacol acyl transferase (CAT) gene was denervated, and the contralateral hindlimb was sham operated. RNase protection analysis revealed that after 72 h denervation decreased CAT mRNA and GLUT-4 mRNA levels 64-85%, respectively (P < 0.05), in the gastrocnemius muscles. In contrast, denervation of the right hindlimb of male rats increased GLUT-1 gene transcription and GLUT-1 mRNA levels by 94 and 213%, respectively (P < 0.05). In conclusion, GLUT-4 transcription is decreased but GLUT-1 transcription is increased in denervated skeletal muscle, suggesting that the effects of denervation on GLUT-4 and GLUT-1 expression are, in part, transcriptionally mediated. Furthermore, these data indicate that a DNA sequence regulated by denervation is located within 730 bp of the 5'-flanking promoter region of the human GLUT-4 gene.

New findings of the correlation between acupoints and corresponding brain cortices using functional MRI

A preliminary study of the correlation between acupuncture points (acupoints) for the treatment of eye disorders suggested by ancient Oriental literature and the corresponding brain localization for vision described by Western medicine was performed by using functional MRI (fMRI). The vision-related acupoint (VA1) is located in the lateral aspect of the foot, and when acupuncture stimulation is performed there, activation of occipital lobes is seen by fMRI. Stimulation of the eye by directly using light results in similar activation in the occipital lobes by fMRI. The experiment was conducted by using conventional checkerboard 8-Hz light-flash stimulation of the eye and observation of the time-course data. This was followed by stimulation of the VA1 by using the same time-course paradigm as visual light stimulation. Results obtained with 12 volunteers yielded very clean data and very close correlations between visual and acupuncture stimulation. We have also stimulated nonacupoints 2 to 5 cm away from the vision-related acupoints on the foot as a control, and activation in the occipital lobes was not observed. The results obtained demonstrate the correlation between activation of specific areas of brain cortices and corresponding acupoint stimulation predicted by ancient acupuncture literature.

Regulation of glucose transporter GLUT-4 and hexokinase II gene transcription by insulin and epinephrine

Transport of glucose across the plasma membrane by GLUT-4 and subsequent phosphorylation of glucose by hexokinase II (HKII) constitute the first two steps of glucose utilization in skeletal muscle. This study was undertaken to determine whether epinephrine and/or insulin regulates in vivo GLUT-4 and HKII gene transcription in rat skeletal muscle. In the first experiment, adrenodemedullated male rats were fasted 24 h and killed in the control condition or after being infused for 1.5 h with epinephrine (30 microg/ml at 1.68 ml/h). In the second experiment, male rats were fasted 24 h and killed after being infused for 2.5 h at 1.68 ml/h with saline or glucose (625 mg/ml) or insulin (39.9 microg/ml) plus glucose (625 mg/ml). Nuclei were isolated from pooled quadriceps, tibialis anterior, and gastrocnemius muscles. Transcriptional run-on analysis indicated that epinephrine infusion decreased GLUT-4 and increased HKII transcription compared with fasted controls. Both glucose and insulin plus glucose infusion induced increases in GLUT-4 and HKII transcription of twofold and three- to fourfold, respectively, compared with saline-infused rats. In conclusion, epinephrine and insulin may regulate GLUT-4 and HKII genes at the level of transcription in rat skeletal muscle.

Transcriptional regulation of hexokinase II in denervated rat skeletal muscle

Hexokinase II protein is augmented in denervated skeletal muscle; therefore, we determined if hexokinase II gene transcription rates and mRNA levels are increased with denervation. The right hindlimb skeletal muscles of male rats were denervated while the left hindlimbs were sham operated. Seventy-two h following surgery, rats were sacrificed and the gastrocnemius and soleus muscles were harvested for nuclear and RNA isolation. Nuclear run-on and ribonuclease protection analyses indicated that denervation increased hexokinase II transcription rates and mRNA levels 42% and 88%, respectively (p < 0.05). Total hexokinase activity rose 23% in denervated gastrocnemius muscle. In conclusion, the increase in hexokinase II gene transcription and mRNA may account for the increase in hexokinase II protein and the subsequent rise in total hexokinase activity in denervated rat skeletal muscle.

Intramolecular isotope effects for benzylic hydroxylation of isomeric xylenes and 4,4'-dimethylbiphenyl by cytochrome P450: relationship between distance of methyl groups and masking of the intrinsic isotope effect

Intramolecular isotope effects associated with the benzylic hydroxylation of a series of selectively deuterated isomeric xylenes and 4,4'-dimethylbiphenyl as catalyzed by various rat liver microsomal preparations and CYP2B1 were determined. Substrate analogs in which each methyl group contained either one (d2 substrates) or two (d4 substrates) deuterium atoms were used to determine the intrinsic isotope effect for the reaction. Specific values of the individual primary (P) and secondary isotope effects (S) were determined. P ranged from a low of 5.32 +/- 0.48 to a high of 7.57 +/- 0.42 depending upon the specific cytochrome P450 preparation used for catalysis. S had an average value of 1.03. The d3 substrates allowed exploration of the effect of distance on the magnitude of the observed isotope effect. The results indicate that the distance of 6.62 A that separates the carbon atoms of the para methyl groups of p-xylene is insufficient to suppress (mask) the intrinsic isotope effect for benzylic hydroxylation by all of the enzyme preparations examined. Conversely, a distance of 11.05 A, the minimal separation between the carbon atoms of the para methyl groups of p,p'-dimethylbiphenyl, is large enough to almost completely mask the intrinsic isotope effect for benzylic hydroxylation by the same set of enzymes.

Quantitative estimation of ultrasonographic attenuation in the myocardium using conventional echocardiographic instrumentation

Through the careful and judicious use of the time gain controls in conventional echocardiographic instrumentation, we have found that it is possible to obtain quantitative estimates of the attenuation of ultrasound beams even in vivo. These estimates are based on the quantitative comparison of the amplitude of the echo waveforms at different depths. Here, we report on such attenuation measurements using both a tissue phantom and the interventricular septum of the myocardium in vivo. The in vitro estimates of attenuation with this method are in agreement with independent laboratory measurements of the same parameter. In vivo measurements on the myocardium indicate oscillations in the magnitude of the attenuation over the heart cycle and suggest methods for the quantitative assessment of a variety of pathologic conditions in the myocardium noninvasively using conventional ultrasound scanners.

Effects of thyroid hormone on GLUT4 glucose transporter gene expression and NIDDM in rats

Previous studies have shown that T3 coordinately stimulates GLUT4-glucose transporter messenger RNA (mRNA) and protein expression in mixed fiber-type skeletal muscle of the rat and produces a concomitant elevation in basal (noninsulin mediated) glucose uptake. The aim of the present study was to 1) determine the precise mechanism(s) for the T3-induced expression of GLUT4 in skeletal muscle, and 2) investigate the potential benefits of T3 on noninsulin dependent diabetes mellitus (NIDDM). Ten daily ip injections of T3 (100 micrograms/100 g BW) administered to hypothyroid male Sprague-Dawley rats, increased both GLUT4 mRNA and transcription approximately 70% (P < 0.05) in mixed fiber-type hindlimb skeletal muscle. Transcriptional induction was subsequently defined to be restricted to red (oxidative) muscle fibers (2.5-fold; P < 0.05), whereas GLUT4 protein was increased in both red and white (glycolytic) skeletal muscle. GLUT4 mRNA and protein expression were similarly inducible in the skeletal muscle of insulin-resistant Zucker rats. More importantly, T3 treatment totally ameliorated hyperinsulinemia in obese animals (P < 0.001), although their moderately elevated plasma glucose levels were not significantly altered. In conclusion, regulation of GLUT4 expression by T3 was shown to lie at the transcriptional level in red skeletal muscle, whereas in white muscle fiber types, it appears to operate via an alternative posttranscriptional mechanism. These data also support the potential of hormonally inducing glucose transporter expression in insulin-resistant muscle. However, high levels of T3 are associated with a number of adverse side-effects, in particular the stimulation of hepatic gluconeogenesis. Nevertheless, future studies may demonstrate, e.g. subthyrotoxic levels, to be similarly effective but without side effects, and thus perhaps find a clinical application in reducing both hyperinsulinemia and hyperglycemia in NIDDM.

Prenatal nicotine effects on memory in rats: pharmacological and behavioral challenges

Cigarette smoking during pregnancy has been shown in a variety of studies to be associated with cognitive deficits in the children. Nicotine administration to rats during gestation has been found to cause subtle cognitive effects in the offspring. Some individual differences in cognitive impairment may be related to prenatal nicotine effects on noradrenergic (NE) systems. In the current study, 10 Sprague-Dawley rat dams were infused with approximately 2 mg/kg/day of nicotine ditartrate via osmotic minipumps and 10 control dams were exposed to vehicle-containing minipumps from gestational day (GD) 4-20. Starting on postnatal day (PND) 50, the offspring were tested for T-maze rewarded spatial alternation with intertrial intervals of 0, 10, 20, or 40 s. There was a sex- and delay-dependent effect of prenatal nicotine exposure on T-maze alternation. Nicotine-exposed males showed a significant deficit at the 0 s delay. In radial-arm maze (RAM) acquisition training there were no significant nicotine effects. However, significant nicotine-related effects were seen with subsequent behavioral and pharmacological challenges in the RAM. Changing the RAM testing location to an identical maze in a different room elicited a significant choice accuracy deficit in the prenatal nicotine-exposed rats compared with controls. Acute nicotine challenge did not cause any differential effects in the prenatal nicotine and control groups. During the isoproterenol (beta-NE agonist) challenge phase there appeared a significant facilitation of choice accuracy and speeding of response in the prenatal nicotine exposure group which was not seen in the control group. The alpha-NE agonist phenylpropanolamine caused a significant deficit in control females but not in the females prenatally exposed to nicotine. No differential effects of the alpha-NE antagonist phenoxybenzamine were seen in the prenatal nicotine and control groups. Throughout RAM testing there was a significant sex effect with males having better choice accuracy than females. These results demonstrate that the persisting cognitive effects of prenatal exposure to 2 mg/kg/day cause subtle effects in cognitive performance which can be elicited with behavioral and pharmacological challenge. These results also support previous studies suggesting the involvement of NE systems in persisting effects of prenatal nicotine exposure.

Differential expression of ob mRNA in rat adipose tissues in response to insulin

The recently cloned obese (ob) gene encodes a fat-specific mRNA and a protein which is believed to regulate satiety and metabolic rate so as to control fat storage. In the present study we investigated rat ob mRNA levels in different fat depots and the effects of insulin infusion on ob mRNA expression. Northern blot analysis showed the abdominal fat (epididymal and perirenal fat pads) had higher ob mRNA levels than subcutaneous fat. After a 2.5-hr infusion of insulin into fasted rats, ob mRNA levels were increased by 3.0 and 1.9-fold in epididymal and perirenal fat pads, respectively. However, no change of ob mRNA level was observed in the subcutaneous fat depot. These data demonstrate adipose depot site-specific expression of ob mRNA and support the hypothesis that insulin plays an important role in the expression of ob mRNA.

Reaction of trifluoroacetaldehyde with amino acids, nucleotides, lipid nucleophiles, and their analogs

Trihaloacetaldehydes are used as sedatives, are key intermediates in the metabolism of 1,1,1,2-tetrahaloethanes, some of which are chlorofluorocarbon substitutes, and are metabolites of trihaloethanols, which are intestinal and bone marrow toxins. In the present study, trifluoroacetaldehyde was used as a model to examine the reactions of trihaloacetaldehydes with cellular nucleophiles, including amino acids, nucleotides, and lipid components. Reaction of trifluoroacetaldehyde hydrate (10 mM) with amino acids (100 mM) in buffer at pH 7.0 and 30 degrees C showed that only L-cysteine formed stable adducts, which were identified as (2R,4R)- and (2S,4R)-2-(trifluoromethyl)thiazolidine-4-carboxylic acid. The absolute stereochemistry of (2R,4R)- and (2S,4R)-2-(trifluoromethyl)thiazolidine-4-carboxylic acid was determined by homonuclear Overhauser effect experiments. The diastereoisomers were formed in a 2.8:1 ratio at 37 degrees C and in a 1:4.0 ratio at 80 degrees C. Trifluoroacetaldehyde also reacted with L-cysteine methyl ester and 2-mercaptoethylamine to form stable thiazolidine derivatives, but did not react with N-acetyl-L-cysteine. The reaction of trifluoroacetaldehyde with the amino groups of ATP, GMP, CMP, L-citrulline, and urea resulted in the formation of stable imines. TMP, which lacks an exocyclic amino group, did not react. Glutathione reacted with trifluoroacetaldehyde to form (2R,5R)- and (2S,5R)-5-amino-6-[carboxymethyl)imino]-2-(trifluoromethyl)-1,3- oxathiane, whose formation was accompanied by simultaneous cleavage of the glutamyl moiety. The reactivity of nucleophilic groups with trifluoroacetaldehyde follows the order SH > NH2 > OH. The results of the present study indicate that trifluoroacetaldehyde covalently modifies cellular nucleophiles. The biological significance of these reactions warrants further investigation. The reaction of trifluoroacetaldehyde with L-cysteine and glutathione may afford routes for the stereoselective synthesis of cysteine prodrugs and five- or six-membered heterocyclic compounds.

Metabolism of 1,2-dichloro-1-fluoroethane and 1-fluoro-1,2,2-trichloroethane: electronic factors govern the regioselectivity of cytochrome P450-dependent oxidation

1,2-Dichloro-1-fluoroethane (HCFC-141) and 1,1,2-trichloro-2-fluoroethane (HCFC-131) were chosen as models to study the regioselectivity of halogenated alkane metabolism. Metabolites in the urine of rats given HCFC-131 ip were the following: inorganic fluoride, chlorofluoroacetic acid, dichloroacetic acid, N-(2-hydroxyethyl)chlorofluoroacetamide, and three unidentified minor metabolites. In vitro incubation of HCFC-131 with either rat liver microsomes from pyridine-treated rats or expressed human cytochrome P450 2E1 isozyme in the presence of NADPH gave fluoride, chlorofluoroacetic acid, and dichloroacetic acid as metabolites. HCFC-141 was biotransformed in rats to inorganic fluoride, chlorofluoroacetic acid, 2-chloro-2-fluoroethanol, and 2-chloro-2-fluoroethyl glucuronide, which were detected in urine. Incubation of HCFC-141 with NADPH-fortified liver microsomes from pyridine-induced rats or expressed human cytochrome P450 2E1 afforded fluoride, chlorofluoroacetaldehyde hydrate, and chloroacetic acid as products. The metabolites identified were consistent with a cytochrome P450-dependent oxidation mechanism. The data also indicated that phosphatidylethanolamine may be a cellular target for chlorofluoroacetyl chloride, a reactive intermediate generated from HCFC-131 by cytochrome P450-dependent oxidation. Chlorofluoroacetic acid given to rats ip was largely recovered in the rat urine, although the formation of inorganic fluoride as a metabolite was observed. The mechanism of defluorination of chlorofluoroacetic acid is not clear. Regioselective oxidation by cytochrome P450 was observed between the two potential oxidizable sites in HCFC-141 and in HCFC-131. Comparison of the observed ratio of oxidation at different sites in in vitro experiments with the calculated activation energies for hydrogen-atom abstraction from these sites indicated that electronic factors are the primary determinant of regioselectivity. In vivo regioselectivity could not be compared with theory since this ratio does not reflect the true regioselectivity due to differences in excretion, reabsorption, secondary metabolism (e.g., fluoride generation from chlorofluoroacetic acid), other routes of fluoride formation, and limitation of the method of detection.

Designing safer chemicals: predicting the rates of metabolism of halogenated alkanes

A computational model is presented that can be used as a tool in the design of safer chemicals. This model predicts the rate of hydrogen-atom abstraction by cytochrome P450 enzymes. Excellent correlations between biotransformation rates and the calculated activation energies (delta Hact) of the cytochrome P450-mediated hydrogen-atom abstractions were obtained for the in vitro biotransformation of six halogenated alkanes (1-fluoro-1,1,2,2-tetrachloroethane, 1,1-difluoro-1,2,2-trichloroethane, 1,1,1-trifluro-2,2-dichloroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1,1,1,2,2,-pentafluoroethane, and 2-bromo-2-chloro-1,1,1-trifluoroethane) with both rat and human enzyme preparations: In(rate, rat liver microsomes) = 44.99 - 1.79(delta Hact), r2 = 0.86; In(rate, human CYP2E1) = 46.99 - 1.77(delta Hact), r2 = 0.97 (rates are in nmol of product per min per nmol of cytochrome P450 and energies are in kcal/mol). Correlations were also obtained for five inhalation anesthetics (enflurane, sevoflurane, desflurane, methoxyflurane, and isoflurane) for both in vivo and in vitro metabolism by humans: In[F(-)]peak plasma = 42.87 - 1.57(delta Hact), r2 = 0.86. To our knowledge, these are the first in vivo human metabolic rates to be quantitatively predicted. Furthermore, this is one of the first examples where computational predictions and in vivo and in vitro data have been shown to agree in any species. The model presented herein provides an archetype for the methodology that may be used in the future design of safer chemicals, particularly hydrochlorofluorocarbons and inhalation anesthetics.

Stereoselectivity and isotope effects associated with cytochrome P450-catalyzed oxidation of (S)-nicotine. The possibility of initial hydrogen atom abstraction in the formation of the delta 1', 5-nicotinium ion

The stereochemical course of cytochromes P450 [P4501A1, P4502B1, P4502B4, and P450101 (P450cam)] catalyzed alpha-carbon oxidations of the cis-(Z)- and trans-(E)-5'-d1 diastereomers of (S)-nicotine has been examined. All enzyme preparations led to the stereoselective abstraction of the 5'-hydrogen atom trans to the pyridine ring with P450101 and human liver microsomal preparations displaying the highest (90%) and P4502B1 the lowest (67%) degree of stereoselectivity. No isotope effect was detected for any of the enzyme-catalyzed reactions, although the existence of an intrinsic isotope effect was inferred by the observation of an intramolecular isotope effect of 2-2.6 observed for the N-demethylation of (S)-N'-dideuteromethylnornicotine. Evidence for P450101-catalyzed N'-oxidation was sought but could not be found at higher than trace levels. These results, together with those obtained by computational methods, are interpreted in terms of an alpha-carbon oxidative pathway involving hydrogen atom abstraction rather than single electron transfer as the initiating event in the P450-catalyzed oxidation of (S)-nicotine to its delta 1',5'-iminium ion metabolite.

Stereospecific activation of the procarcinogen benzo[a]pyrene: a probe for the active sites of the cytochrome P450 superfamily

It has been established previously that the sterochemistry of epoxidation of the procarcinogen benzo[a]pyrene determines the potency of the ultimate carcinogen. Herein we report that seven human P450s, five rodent P450s, and two bacterial P450s all convert B[a]P to the most potent carcinogenic often differ in both regioselectivity and stereoselectivity. This is likely due to the large size of the substrate molecule and its constraints in the active sites. Smaller substrates that can rotate more freely in the active site may be expected to have greater variations in binding orientations and therefore greater differences in stereoselectivities. Molecular mechanics is used to determine the specific amino acids responsible for the stereochemical outcome. Molecular dynamics is then used to strengthen the hypothesis that a single helical region, one that is likely to be conserved in all P450s, plays a primary role in determining the stereoselectivity of the reaction.

Potent inhibitors of human inosine monophosphate dehydrogenase type II. Fluorine-substituted analogues of thiazole-4-carboxamide adenine dinucleotide

Three analogues of thiazole-4-carboxamide adenine dinucleotide (TAD) (1-3) containing a fluorine atom at the C2' of the adenine nucleoside (in the ribo and arabino configuration) and at the C3' (in the ribo configuration) were synthesized in high yield from the corresponding 5'-monophosphates of 2'-deoxy-2'-fluoroadenosine (9), 9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-adenine (17), and 3'-deoxy-3'-fluoroadenosine (14), respectively. Pure 2',3'-O-isopropylidene-tiazofurin 5'-phosphorimidazolide (8) was obtained by phosphorylation of the protected tiazofurin followed by treatment with carbonyldiimidazole and HPLC purification. Reaction of 8 with 9 in DMF-d7 (monitored by 1H and 31P NMR) afforded the desired dinucleotide 12, which after deisopropylidenation gave 1 in 82% yield. Small amounts of symmetrical dinucleotides AppA (10, 7.2%) and TRppTR (11, 8.0%) were also isolated during HPLC purification of the major product 12. In a similar manner, compounds 2 and 3 were obtained by coupling of 8 with 14 and 17 in 80% and 76% yield, respectively. All newly prepared fluoro-substituted compounds as well as beta-CF2-TAD, earlier synthesized by us, showed good inhibitory activity against inosine monophosphate dehydrogenase type II, the isozyme which is predominant in neoplastic cells. Binding of 1 (Kis = 0.5 microM), 2 (Kis = 0.7 microM), and 3 (Kis = 2.9 microM) was comparable to that of TAD (Ki = 0.2 microM). The difluoromethylene bisphosphonate analogue, beta-CF2-TAD (Ki = 0.17 microM), was found to be equally effective as the best cofactor-type inhibitor, beta-CH2-TAD (Ki = 0.11 microM). Interestingly, the level of inhibition of horse liver alcohol dehydrogenase by these compounds was found to be much lower (0.1 mM for 1 and 2 and no inhibition up to 10 mM for 3). These findings show that inhibition of tumor-induced inosine monophosphate dehydrogenase type II is selective and may be of therapeutic interest.

Metabolism of 1-fluoro-1,1,2-trichloroethane, 1,2-dichloro-1,1-difluoroethane, and 1,1,1-trifluoro-2-chloroethane

1-Fluoro-1,1,2-trichloroethane (HCFC-131a), 1,2-dichloro-1,1-difluoroethane (HCFC-132b), and 1,1,1-trifluoro-2-chloroethane (HCFC-133a) were chosen as models for comparative metabolism studies on 1,1,1,2-tetrahaloethanes, which are under consideration as replacements for ozone-depleting chlorofluorocarbons (CFCs). Male Fischer 344 rats were given 10 mmol/kg ip HCFC-131a or HCFC-132b or exposed by inhalation to 1% HCFC-133a for 2 h. Urine collected in the first 24 h after exposure was analyzed by 19F NMR and GC/MS and with a fluoride-selective ion electrode for the formation of fluorine-containing metabolites. Metabolites of HCFC-131a included 2,2-dichloro-2-fluoroethyl glucuronide, 2,2-dichloro-2-fluoroethyl sulfate, dichlorofluoroacetic acid, and inorganic fluoride. Metabolites of HCFC-132b were characterized as 2-chloro-2,2-difluoroethyl glucuronide, 2-chloro-2,2-difluoroethyl sulfate, chlorodifluoroacetic acid, chlorodifluoroacetaldehyde hydrate, chlorodifluoroacetaldehyde-urea adduct, and inorganic fluoride. HCFC-133a was metabolized to 2,2,2-trifluoroethyl glucuronide, trifluoroacetic acid, trifluoroacetaldehyde hydrate, trifluoroacetaldehyde-urea adduct, inorganic fluoride, and a minor, unidentified metabolite. With HCFC-131a and HCFC-132b, glucuronide conjugates of 2,2,2-trihaloethanols were the major urinary metabolites, whereas with HCFC-133a, a trifluoroacetaldehyde-urea adduct was the major urinary metabolite. Analysis of metabolite distribution in vivo indicated that aldehydic metabolites increased as fluorine substitution increased in the order HCFC-131a < HCFC-132b < HCFC-133a. With NADPH-fortified rat liver microsomes, HCFC-133a and HCFC-132b were biotransformed to trifluoroacetaldehyde and chlorodifluoroacetaldehyde, respectively, whereas HCFC-131a was converted to dichlorofluoroacetic acid. No covalently bound metabolites were detected by 19F NMR spectroscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of self-esteem and wellness in health promotion professionals

When researchers tested 90 wellness professionals attending the National Wellness Conference using the Adult Form of Coopersmith's Self-esteem Inventory and TestWell, participants scored above the norm on self-esteem and over-all wellness and on the subscales of Sexuality and Emotional Awareness, Safety, and Emotional Management. In addition, TestWell, a revised wellness inventory, showed internal reliability (alpha) of .84.

Dose-response study of intravenous torsemide in congestive heart failure

In a double-blind dose-response study, 49 patients with New York Heart Association functional class III or IV heart failure were randomized to receive a single intravenous dose of 5, 10, or 20 mg torsemide or 40 mg furosemide. Torsemide produced dose-related decreases in body weight and increases in sodium and chloride excretion and urine volume. With the 20 mg dose of torsemide and the 40 mg dose of furosemide, body weight decreased significantly relative to baseline, and total and fractional 24-hour urinary excretion of sodium, chloride, and potassium and urine volume increased significantly. The 10 mg torsemide dose also produced a significant increase in urine volume. The results indicate that intravenous torsemide is effective for the acute treatment of sodium and fluid retention resulting from moderate to severe congestive heart failure.

Correlation between fructose 2,6-bisphosphate and lactate production in skeletal muscle

The epinephrine-induced production of lactate in nonexercising muscles may be due in part to allosteric activation of 6-phosphofructo-1-kinase by fructose 2,6-bisphosphate (F-2,6-P2). To determine if a correlation exists between F-2,6-P2 and lactate production in skeletal muscle, isolated rat hindlimbs were perfused for 30 min with a medium containing epinephrine at concentrations varying between 1.7 +/- 0.5 and 72.4 +/- 4.2 nM. In comparison to control values, hindlimbs perfused with 72.4 +/- 4.2 nM epinephrine had a two- to threefold increase in F-2,6-P2 and a fourfold increase in muscle lactate production. Hindlimb lactate production was highly correlated to gastrocnemius adenosine 3',5'-cyclic monophosphate (r = 0.80), fructose 6-phosphate (r = 0.87), and F-2,6-P2 (r = 0.81). The adenosine 3',5'-cyclic monophosphate-mediated increase in glycogenolysis with consequent increase in fructose 6-phosphate (substrate for 6-phosphofructo-1-kinase and 6-phosphofructo-2-kinase) is likely important for induction of lactate production by inactive muscle. The high correlation between muscle F-2,6-P2 and muscle lactate production at varying concentrations of epinephrine supports the hypothesis that the epinephrine-induced activation of glycolysis and lactate production in nonexercising muscle is mediated in part by increases in F-2,6-P2 levels.

Low-dose radiography of scoliosis in children. A comparison of methods

STUDY DESIGN

Records of 1,582 conventional and computed radiographic examinations performed to evaluate scoliosis were reviewed and compared to determine differences in total radiation burden.

OBJECTIVE

This study evaluated the impact of computed radiographic imaging (CRI) on radiation exposure in children undergoing serial spinal radiographs for scoliosis assessment and compared exposure from CRI with that of low-dose film-screen combinations.

SUMMARY OF BACKGROUND DATA

CRI permits diagnostic radiographic studies to be performed with a dose reduction of 80%-95% compared to conventional film-screen systems. High speed film-screen systems also permit a significantly lower exposure. Each approach has unique advantages and disadvantages.

METHODS

Over 6 years, we performed 1,582 spinal examinations in children 4-14 years old using reduced dosage techniques with computed radiography. The images were obtained with Fuji FCR 101 and Philips PCR/SP systems. The adequacy of diagnostic image quality in the serial evaluation of scoliosis at different exposure levels was evaluated and compared with regular and film-screen systems with speeds ranging from 250 to 1,200.

RESULTS

Diagnostic-quality images for evaluating scoliosis can be obtained with doses of 5% or less than required with conventional film-screen systems. Computed radiography provides image quality and dose reduction comparable to a 1,200-speed film-screen system.

CONCLUSION

CRI gives satisfactory images at 5% reduction of the standard film-screen dose. Based on comparison with a 1,200 speed film-screen system, CRI provides equal or better image quality at a similar radiation dose. The cost of CRI is higher than for film-screen radiography, but wide latitude and the ability to tailor dose with requirements for image quality are significant advantages for CRI.

CNAD: a potent and specific inhibitor of alcohol dehydrogenase

CNAD (5-beta-D-ribofuranosylnicotinamide adenine dinucleotide) is an isosteric and isomeric analogue of NAD, in which the nicotinamide ring is linked to the sugar via a C-glycosyl (C5-C1') bond. CNAD acts as a general dehydrogenase inhibitor but shows unusual specificity and affinity for liver alcohol dehydrogenase (ADH, EC 1.1.1.1). The pattern of inhibition is congruent to 4 nM, with NAD as the variable substrate. These values are 3-5 orders of magnitude smaller than those obtained for CNAD in other dehydrogenases and are comparable to values observed for the tightest binding ADH inhibitors known. The specificity and affinity of CNAD for ADH are likely due to coordination of the zinc cation at the ADH catalytic site by the CNAD pyridine nitrogen. This is supported by kinetic and computational studies of ADH-CNAD complexes. These results are compared with those for a related analogue, CPAD. In this analogue, displacement of the pyridine nitrogen to the opposite side of the ring removes the specificity for ADH.

Muscle fructose-2,6-bisphosphate and glucose-1,6-bisphosphate during insulin-induced hypoglycemia

Glucose production during insulin-induced hypoglycemia in the fasted state is heavily dependent on the process of hepatic gluconeogenesis. Skeletal muscle glycogen is one possible source of lactate for hepatic gluconeogenesis. Fructose 2,6-bisphosphate (F-2,6-P2) and glucose 1,6-bisphosphate (G-1,6-P2) are two allosteric activators of muscle glycolysis. To investigate their putative role in the control of muscle lactate production during hypoglycemia, fasted rats were infused via jugular catheters with insulin in 0.9% NaCl or with 0.9% NaCl alone for 60 or 120 min. Muscles were removed and clamp frozen in liquid nitrogen. The insulin infusion produced plasma insulin values of 97 +/- 13 microU/ml after 1 h and 100 +/- 9 microU/ml after 2 h. Blood glucose in the saline-infused rats was 4.6 +/- 0.2 mM after 1 h and 5.1 +/- 0.1 mM after 2 h compared with 1.5 +/- 0.01 and 1.0 +/- 0.1 mM after 1 and 2 h, respectively, in the insulin-infused rats. The hypoglycemic rats had significantly elevated plasma epinephrine and blood lactate levels compared with the saline-infused rats. F-2,6-P2 and G-1,6-P2 were increased two- to five-fold in white quadriceps of hypoglycemic rats compared with that of saline-infused rats. The results are consistent with F-2,6-P2 and G-1,6-P2 playing a role in stimulating muscle lactate production as a source of gluconeogenic substrate during insulin-induced hypoglycemia.

Mechanistic studies of uridine diphosphate glucuronosyltransferase

Bisubstrate reaction kinetics and product inhibition studies were used to characterize the kinetic mechanism of a partially purified uridine diphosphate glucuronosyltransferase (UDPGT). These studies indicate that the reaction most likely occurs via a random order sequential mechanism. The effect of electron withdrawing and donating groups on the rate of reaction was also determined. It was found that electron donating groups increased the rate of glucuronide conjugation. This result is consistent with nucleophilic attack of the C-1 carbon of the UDP-glucuronic acid (UDPGA) by an SN2 mechanism. This is the first direct evidence for a SN2 mechanism in UDPGT catalysis.

The pathophysiologic role of fat in dysbaric osteonecrosis

Dysbaric osteonecrosis (DON) can occur in humans and sheep after a single hyperbaric air exposure with inadequate decompression. The authors hypothesize that DON does not result from primary embolic or compressive effects of nitrogen bubbles on the osseous vasculature, but by secondary injury to the marrow adipose tissue by rapidly expanding nitrogen gas that triggers local, and possibly systemic, intravascular coagulation. A 28-year-old scallop diver remained at a depth of 92 feet in sea water for 4.5 hours on surface-supplied compressed air. Decompression sickness occurred after a no-stop ascent to the surface, and he died 70 minutes later. Autopsy showed multiple gas bubbles, not only within the great vessels, but in the fatty marrow of his femoral and humeral heads. Lipid and platelet aggregates were found on the surface of marrow bubbles. Fibrin-platelet thrombi were detected within dilated venous sinusoids adjacent to bubbles, and in veins, capillaries, and arterioles. Since pulmonary, renal, and intraosseous (subchondral) fat embolism and fibrin thromboses were observed, it is suggested that injured marrow adipocytes can release liquid fat, thromboplastin, and other vasoactive substances, which conceivably can also play a systemic procoagulant role in triggering disseminated intravascular coagulation and additional DON.

Slow-binding inhibition of carboxylesterase and other serine hydrolases by chlorodifluoroacetaldehyde

The chlorofluorocarbon substitute 1,2-dichloro-1,1-difluoroethane (HCFC-132b) undergoes oxidative metabolism in rats to give a range of metabolites, including chlorodifluoroacetaldehyde [Harris and Anders (1991) Chem. Res. Toxicol. 4, 180]. The present experiments were undertaken after studies to characterize an unidentified metabolite of HCFC-132b revealed that chlorodifluoroacetaldehyde was toxic in vivo: rats given chlorodifluoroacetaldehyde died showing signs of cholinergic stimulation. Because some fluoroketones are known inhibitors of hydrolases, including acetylcholinesterase, the inhibitory effects of chlorodifluoroacetaldehyde on acetylcholinesterase (electric eel and human erythrocyte), on pseudocholinesterase (horse serum), on carboxylesterase (pig liver), and on alpha-chymotrypsin (bovine pancreas) were studied. In aqueous solution, the ratio chlorodifluoroacetaldehyde:chlorodifluroacetaldehyde hydrate, as determined by 1H nuclear magnetic resonance spectroscopy, was 1:157. Chlorodifluoroacetaldehyde was a slow-binding inhibitor of both acetylcholinesterases, of pseudocholinesterase, and of carboxylesterase; the Ki values, corrected for the aldehyde:hydrate ratio, were 150 nM, 1.7 nM, 3.7 nM, and 23 pM, respectively, as determined by final velocity of the progress curves; the kon values were 9.1 x 10(4), 1.1 x 10(5), 3.2 x 10(4), and 9.2 x 10(5) M-1 min-1, respectively. Chlorodifluoroacetaldehyde did not inhibit alpha-chymotrypsin. Acetaldehyde and trichloroacetaldehyde were classical competitive inhibitors of acetylcholinesterase. These results show that hydrochlorofluorocarbon metabolites may exert significant biological effects.

Fat embolism, intravascular coagulation, and osteonecrosis

A triad of intraosseous fat embolism, intravascular coagulation (both thrombosis and hemorrhage), and osteonecrosis was pathologically demonstrated to coexist for the first time in humans. Specimens were evaluated from the earliest nontraumatic (18 hours) and traumatic (29 hours) femoral head lesions yet reported, and the cause and early pathogenesis were confirmed in a third case. An absolute overload of subchondral fat emboli, with hypercoagulability, stasis, and endothelial damage by free fatty acids, appears to cause end-organ death by triggering intravascular coagulation. This intermediary pathway appears to be capable of producing osteonecrosis by progressive fibrin platelet thromboses, which begin in vulnerable subchondral capillaries and sinusoids, especially when associated with arteriolar vasoconstriction and impaired secondary fibrinolysis (reperfusion of necrotic vessels with peripheral marrow hemorrhages). A relative overload of subperiosteal and subchondral fat emboli, which is below the ischemic/anoxic threshold but insufficient for intravascular coagulation, may cause osteopenia.

Effect of adrenodemedullation on decline in muscle malonyl-CoA during exercise

Malonyl-CoA is an inhibitor of carnitine palmitoyltransferase, a rate-limiting enzyme of fatty acid oxidation. Previous studies have indicated that muscle malonyl-CoA declines in rats during treadmill running. This decrease may be important for allowing an increased rate of fatty acid oxidation during prolonged exercise. This study was designed to determine whether epinephrine is essential for inducing the decline in muscle malonyl-CoA during exercise. Male Sprague-Dawley rats underwent adrenodemedullation (ADM) or sham operation. After allowing 3 wk for recovery, rats were killed (pentobarbital anesthesia) at rest or after running at 21 m/min up a 15% grade for 60 min. Red quadriceps malonyl-CoA decreased from 2.6 +/- 0.3 to 0.8 +/- 0.07 nmol/g in sham-operated rats and from 2.2 +/- 0.3 to 0.8 +/- 0.1 nmol/g in ADM rats. White quadriceps malonyl-CoA decreased to similar levels during exercise in both sham-operated and ADM rats. A second experiment on 24-h fasted rats also showed no impairment in the exercise-induced decline in red quadriceps malonyl-CoA as a result of adrenodemedullation. The hormones of the adrenal medulla are therefore unessential for inducing the decline in malonyl-CoA during exercise.

Predicting the cytochrome P450 mediated metabolism of xenobiotics

The cytochrome P450s play a unique role in the metabolism of xenobiotics. Characteristics which allow a vast number of foreign compounds to be metabolized by a limited number of enzymes include broad substrate specificity and broad regioselectivity. Because of their importance in both the metabolism and toxicity of drugs and environmental contaminants, efforts are being made to use computational methods to predict these biotransformation pathways. This review describes the recent progress towards the prediction of the tertiary structures of the various P450s and the determination of the electronic characteristics of substrates which determine their tendency to be oxidized by the P450s.

The added gradient echo pulse sequence technique: application to imaging of fluid in the temporomandibular joint

PURPOSE

To assess the value of an added gradient echo in the same pulse sequence with a T1-weighted spin echo for determining the presence of an abnormal fluid collection in the temporomandibular joint with no additional imaging time.

MATERIALS AND METHODS

Using a standard T1-weighted sequence used in cine temporomandibular joint imaging, a readout gradient reversal was added and the resulting gradient echo collected. This image was compared with standard T1- and T2-weighted sequences, a short inversion recovery imaging sequence, and a small flip angle fast low-angle shot gradient-echo sequence.

RESULTS

The T1-weighted spin echo preceding the added gradient echo is not affected by the gradient reversal, but the additional gradient echo adds T2* contrast information that displays fluid as bright as and compares favorably with other fluid detection sequences.

CONCLUSION

The added gradient-echo technique adds sensitivity for the detection of an abnormal increase in fluid in the temporomandibular joint without adding to the overall imaging time of a routine T1-weighted sequence.

Laparoscopic intraperitoneal marsupialization: report on a new treatment for lymphoceles

Lymphocele formation, a common complication of pelvic surgery, can produce considerable morbidity. Treatment is problematic, with no single procedure considered optimal. We recently treated a 67-year-old man with a symptomatic lymphocele by laparoscopic internal marsupialization. Total operative time was 45 min, and the patient was discharged home the same day with minimal need for pain medications. Total resolution of the symptoms occurred within 24 h. In comparison to other methods compiled and analyzed from the literature, this highly effective, minimally invasive procedure offers a significant advantage to the patient.

Visualization of myocardial cellular architecture using acoustic microscopy

The resolution of an ultrasound transducer depends on its frequency. The resolution improves when higher frequency transducers are used. A 1000 MHz transducer has a resolution of approximately 1 micron. Acoustic microscopy utilizes very high-frequency ultrasound (600 to 1000 MHz) to visualize structures on a microscopic level. Unstained, deparaffinized, 5 microns sections of myocardial biopsy specimens from 10 patients were placed on a slide and imaged using an Olympus UH3 scanning acoustic microscope. To compare with light microscopy, the section used for acoustic microscopy was subsequently stained with hematoxylin and eosin and a serial section from the paraffin block was stained with PTAH stain. Myocytes, myofibrils, and interstitial tissue were accurately imaged. Pathologic phenomena such as cell fallout, interstitial fibrosis, and lymphocytic infiltration were identified by acoustic microscopy. Intramural vessels, nuclei of endothelial cells, and the media were clearly identified by this technique. There was close correlation between findings by acoustic microscopy and light microscopy. Acoustic microscopy permitted the visualization of cardiac cellular detail with a resolution similar to that of light microscopy. Unlike light microscopy, acoustic microscopy requires no staining of the specimen.

Cine magnetic resonance imaging of the temporomandibular joint

Magnetic resonance imaging (MRI) provides a significant amount of information about both the position of the meniscoligamentous complex and the osseous structures in evaluation of internal derangements of the temporomandibular joint (TMJ). With the advent of computer-driven cine displays, dynamic information is now available, providing cost-effective diagnostic evaluation similar to cine fluoroscopy with arthrography, but without the ionizing radiation exposure or discomfort. Using a bite block, a series of sagittal images are obtained with the patient "posing" at different degrees of jaw opening. The subsequent cine MRIs with "posed" motion are striking and very helpful in evaluating various types of TMJ dysfunction. At the authors' institution, 205 patients were examined with a history of TMJ arthralgia. Correlation of imaging studies and surgical findings reveals a sensitivity (98%) and specificity (96%) for identifying the meniscoligamentous complex.

Laparoscopic cystectomy: initial report on a new treatment for the retained bladder

The retained bladder of a 27-year-old paraplegic woman suffering from recurrent pyocystis was removed laparoscopically. Operative time was 130 minutes. Postoperative hospital stay was 5 days, which was significantly less than that in 5 similar patients undergoing open cystectomy for vesical empyema in whom the mean hospital stay was 20.6 days. We believe that laparoscopic cystectomy represents a plausible, minimally invasive alternative to standard cystectomy for the symptomatic bladder left behind after supravesical urinary diversion.

Laparoscopic diverticulectomy: preliminary report of a new approach for the treatment of bladder diverticulum

Laparoscopic techniques have expanded the possibilities of endo-surgically approaching urological abnormalities that would otherwise be managed via an open operation. We report on another useful application of the laparoscope, bladder diverticulectomy. A large bladder diverticulum, responsible for incomplete bladder emptying and recurrent urinary tract infections in an 87-year-old man, was successfully excised endoscopically. The technique and possible future indications are described.

Pentahaloethane-based chlorofluorocarbon substitutes and halothane: correlation of in vivo hepatic protein trifluoroacetylation and urinary trifluoroacetic acid excretion with calculated enthalpies of activation

The hydrochlorofluorocarbons (HCFCs) 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) and 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124) and the hydrofluorocarbon (HFC) pentafluoroethane (HFC-125) are being developed as substitutes for chlorofluorocarbons that deplete stratospheric ozone. The structural similarity of these HCFCs and HFCs to halothane, which is hepatotoxic under certain circumstances, indicates that the metabolism and cellular interactions of HCFCs and HFCs must be explored. In a previous study [Harris et al. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 1407], similar patterns of trifluoroacetylated proteins (TFA-proteins) were detected by immunoblotting with anti-TFA-protein antibodies in livers of rats exposed to halothane or HCFC-123. The present study extends these results and demonstrates that in vivo TFA-protein formation resulting from a 6-h exposure to a 1% atmosphere of these compounds follows the trend: halothane approximately HCFC-123 much greater than HFC-124, greater than HFC-125. The calculated enthalpies of activation of halothane, HCFC-123, HCFC-124, and HFC-125 paralleled the observed rate of trifluoroacetic acid excretion in HCFC- or HFC-exposed rats. Exposure of rats to a range of HCFC-123 concentrations indicated that TFA-protein formation was saturated at an exposure concentration between 0.01% and 0.1% HCFC-123. Deuteration of HCFC-123 decreased TFA-protein formation in vivo. Urinary trifluoroacetic acid excretion by treated rats correlated with the levels of TFA-proteins found after each of these treatments. No TFA-proteins were detected in hepatic fractions from rats given 1,1,1,2-tetrafluoroethane (HFC-134a), which is not metabolized to a trifluoroacetyl halide.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-induced hypoglycemia in fed and fasted exercising rats

To determine running performance and hormonal and metabolic responses during insulin-induced hypoglycemia, fed and fasted male rats (315 +/- 3 g) were infused with insulin (100 mU/ml, 1.5 ml/h) or saline (1.5 ml/h) for 60 min and then killed at rest or after running on the treadmill (21 m/min, 15% grade). Insulin-infused fed rats ran poorly during the second 10 min of a 20-min exercise test. They were capable of running a total of 43 +/- 5 min, compared with 138 +/- 6 min for saline-infused fed rats. Fasted insulin-infused rats were able to run only 12.8 +/- 0.8 min, compared with 122 +/- 15 min for fasted saline-infused rats. In fasted rats, blood glucose was 1.6 +/- 0.1 mM after 60 min of insulin infusion and 1.2 +/- 0.1 mM after running to exhaustion. Artificial increase of plasma free fatty acids had no effect on performance. Intravenous infusion of glucose at the time of fatigue produced an immediate recovery, allowing the formerly fatigued rats to run 20 min without development of fatigue. These results provide evidence that severe hypoglycemia can be a significant cause of fatigue, even if it occurs early in the course of an exercise bout.

Intravascular coagulation and osteonecrosis

Current evidence suggests that intravascular coagulation (IC), an intermediary mechanism, is the most likely final common pathway by which intraosseous fat embolism causes nontraumatic osteonecrosis (ON). Stage 1A lesions (fatty osteocytic necrosis) appear to progress to classic Stage 1B lesions (ischemic degeneration of necrotic osteocytes and adipocytes) when the ischemic threshold is exceeded by absolute subchondral fat overload with insufficient local clearance of procoagulants, especially tissue thromboplastin. The result is vascular stasis, hypercoagulability, endothelial damage (by free fatty acids) and IC, especially if there is coexistent subchondral vasoconstriction and impaired secondary fibrinolysis. Osteonecrosis can be produced in animals by IC, which begins in the vulnerable subchondral microcirculation (Arthus phenomenon). Cartography (embolic scintimetry with superselective angiography) indicates early complete devascularization of the femoral head, suggesting progressive venous and retrograde arterial thrombosis. Increased plasma fibrinopeptide A and direct histologic evidence of intraosseous thromboses and peripheral hemorrhages further indicate that IC is the final pathway. Best evidence are 51 ON lesions complicating disseminated IC in eight children (Shwartzman phenomenon), with collateral histologic evidence of intraosseous thrombosis and ON.

Modification by focused ultrasound pulses of electrically evoked responses from an in vitro hippocampal preparation

The application of short pulses of focused ultrasound was studied as a method of modifying electrically evoked responses in the mammalian brain. The in vitro hippocampal preparation was employed to facilitate delivery and dosimetry of ultrasound, and assessment of mechanisms of ultrasound effects. Cellular and dendritic field potential responses evoked by electrical stimulation of the Schaffer/Commissural afferents were examined before, during and after exposure of a portion of the CA1 region to focused ultrasound pulses for periods ranging from 2 to 15 min. Focused ultrasound with a repetition rate of 150 kHz was delivered in pulses comparable in duration to an electrical pulse that could initiate activity in the nervous system. The pulses had a center frequency of 750 kHz, durations of about 6 microseconds, and spatial-peak-temporal-averaged intensities of about 80 W/cm2. These parameters are markedly different from those employed in conventional diagnostic ultrasound. Temperatures in the bath and tissue were monitored. Extracellular field potentials reflecting the presynaptic fiber volley, dendritic response and cellular discharge were significantly reduced by exposure to ultrasound. Recovery occurred to varying degrees, and in one experiment was complete. Average temperature changes observed were less than 1 degree C. The present study demonstrates that the electrically evoked response in mammalian brain can be altered by ultrasound in a non-thermal, non-cavitational mode, and that such effects are potentially reversible.

Secondary 18O isotope effects for hexokinase-catalyzed phosphoryl transfer from ATP

Secondary 18O isotope effects in the gamma-position of ATP have been measured on phosphoryl transfer catalyzed by yeast hexokinase in an effort to deduce the structure of the transition state. The isotope effects were measured by the remote-label method with the exocyclic amino group of adenine as the remote label. With glucose as substrate, the secondary 18O isotope effect per 18O was 0.9987 at pH 8.2 and 0.9965 at pH 5.3, which is below the pK of 6.15 seen in the V/K profile for MgATP. With the slow substrate 1,5-anhydro-D-glucitol, the value was 0.9976 at pH 8.2. While part of the inverse nature of the isotope effect may result from an isotope effect on binding, the more inverse values when catalysis is made more rate limiting by decreasing the pH or switching to a slower substrate suggest a dissociative transition state for phosphoryl transfer, in agreement with predictions from model chemistry. The 18O equilibrium isotope effect for deprotonation of HATP3- is 1.0156, while Mg2+ coordination to ATP4- does not appear to be accompanied by an 18O isotope effect larger than 1.001.

Scanning acoustic microscopy of neoplastic and inflammatory cutaneous tissue specimens

Acoustic microscopy utilizes high frequency ultrasound to generate microscopic images. The current study was designed to examine representative disorders of the skin by use of a reflective scanning acoustic microscope (R-SAM), and to determine whether the obtainable resolution was sufficient to render a microscopic diagnosis. An Olympus UH3 Scanning Acoustic Microscope was utilized with lenses producing burst wave frequencies at 600 and 800 MHz (600 and 800 million cylces/sec). Cutaneous tissue specimens representing 12 different neoplastic and inflammatory disorders were examined. Acoustic images of unstained sections were compared with conventional light microscopic study of sections stained with hematoxylin-eosin. In most neoplasms examined, it was possible to make a specific diagnosis primarily from low magnification pattern analysis. Although individual cells could be visualized, cytologic atypia was poorly defined. In the inflammatory disorders, a specific diagnosis was possible in all but bullous pemphigoid and lichen planus, because the composition of the inflammatory infiltrate was difficult to determine. The advantages of the R-SAM include the capability of producing an acoustic profile of the tissue and the future possibility of in situ diagnosis.

The double jeopardy of sales promotions

The maturing of most consumer markets in the United States has put great pressure on manufacturers in their search for growth. They have concentrated on building sales and expanding share proportions in the stagnant markets with devices like niche products, product extensions, mergers, and international ventures. They have shifted emphasis to sales promotions at the expense of advertising. But promotions, when you come right down to it, mean price reductions. Trade promotions are almost always rebates, and consumer promotions are usually temporary price reductions or coupons. The cost in reduced profit, demonstrated mathematically through calculations of price elasticity, is severe. Besides, when the promotion is over, the manufacturer has not moved forward an inch in shoring up the brand franchise. Promotions bring volatile demand, whereas the producer seeks stable demand. By sustaining a brand image and building customer loyalty, on the other hand, theme advertising can stabilize demand. Moreover, this type of advertising is less likely than promotion is to invite destructive competitive retaliation. Calculation of the advertising elasticity of a brand indicates that sometimes even modest sales increases can produce healthy profit improvement. In a well-planned marketing campaign, there is often good reason to include trade or consumer promotion--to counter a leading competitor's moves, for example. But there is no point in carrying out wild swings at rivals in a struggle for market share. Mathematical techniques can aid the efficiency of marketing planning and put on a more rational basis the decision on where to put the dollars.

Intrinsic isotope effects suggest that the reaction coordinate symmetry for the cytochrome P-450 catalyzed hydroxylation of octane is isozyme independent

The mechanism of the omega-hydroxylation of octane by three catalytically distinct, purified forms of cytochrome P-450, namely, P-450b, P-450c, and P-450LM2, was investigated by using deuterium isotope effects. The deuterium isotope effects associated with the omega-hydroxylation of octane-1,1,1-2H3, octane-1,8-2H2, and octane-1,1,8,8-2H4 by all three isozymes were determined. From these data the intrinsic isotope effects were calculated and separated into their primary and secondary components. The primary intrinsic isotope effect for the reaction ranged from 7.69 to 9.18 while the secondary intrinsic isotope effect ranged from 1.13 to 1.25. Neither the primary nor secondary isotope effect values were statistically different for any of the isozymes investigated. These data are consistent with a symmetrical transition state for a mechanism involving initial hydrogen atom abstraction followed by hydroxyl radical recombination which is essentially independent of the specific isozyme catalyzing the reaction. It is concluded that (1) in general the porphyrin-[FeO]3+ complex behaves as a source of a triplet-like oxygen atom, (2) the regioselectivity for the site of oxidation is dictated by the apoprotein of the specific isozyme of cytochrome P-450 catalyzing the reaction, and (3) the maximum primary intrinsic isotope effect for any cytochrome P-450 catalyzed oxidation of a carbon center is about 9, assuming no tunneling effects.