Blockade of corticotropin-releasing hormone receptors reduces spontaneous waking in the rat

We have previously hypothesized that corticotropin-releasing hormone (CRH) is involved in the regulation of physiological waking. To further elucidate this role for CRH, we administered intracerebroventricularly into rats two specific CRH-receptor antagonists, alpha-helical CRH-(9-41) (alpha-hCRH) or astressin, and determined changes in electroencephalogram-defined waking and sleep. Our results indicate that both of these receptor antagonists reduce the amount of time spent awake in a dose-related manner when administered before the dark period of the light-dark cycle. However, the time courses for these effects differ between antagonists; effective doses of alpha-hCRH reduce waking during the first 2 h postinjection, whereas effective doses of astressin reduce waking during postinjection hours 7-12. In contrast to dark-onset administrations, the amount of waking is not altered by either CRH-receptor antagonist when administered before the light period. These results support our hypothesis that CRH contributes to the regulation of physiological waking, since interfering with the binding of CRH to its receptor reduces spontaneous waking.

Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate -- a structural isomer of VX

O-Isobutyl S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chemical warefare agent, O-ethyl S-[2(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 microg kg(-1); s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, approximately 13 min post-VR; Group 2, approximately 6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, approximately 28 min post-VR; Group 2, approximately 15 min post-VR). An idioventricular rhythm, which signalled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (approximately 1 min prior to respiratory failure). Thus, in addition to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in precipitating a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

Effects of tetramethylpyrazine on portal hypertensive rats

The effects of tetramethylpyrazine, an alkaloid isolated from a Chinese herb Ligusticum wallichii Franch have been assessed in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation in Sprague-Dawley rats. Two weeks after ligation, when the hyperdynamic state had stabilized, rats were anaesthetized after an overnight fast and cannulated for measurement of mean arterial pressure, portal venous pressure, cardiac index and heart rate. Tetramethylpyrazine (3.0, 9.9 and 30mgkg(-1)) induced dose-dependent reductions of portal venous pressure and mean arterial pressure after intravenous infusion. The maximum percentage reduction of portal venous pressure after tetramethylpyrazine was 6.0+/-0.8, 9.3+/-1.6 and 20+/-2% of baseline for doses of 3.0, 9.9 and 30.0mgkg(-1), respectively. Also, total peripheral resistance was significantly reduced by tetramethylpyrazine and cardiac index was slightly increased. Our results showed that tetramethylpyrazine induced portal pressure reduction in portal hypertensive rats.

325-nm Interference Microscope

We first discuss an interference microscope's 3D response in terms of Richards and Wolf's vector theory. We then report the results we obtained with a 325-nm interference microscope using an ultraviolet transparent beam splitter, short-working-distance Mirau interferometer. The microscope performs at near-ideal definitions with a measured FWHM of the intensity spot at 0.14 mum and a FWHM of the depth envelope intensity at 0.25 mum. Feasibility of a shorter wavelength system operating at 248 nm is demonstrated.

Recovery from the lethal effects of saxitoxin: a therapeutic window for 4-aminopyridine (4-AP)

We have shown that saxitoxin (STX) induced lethality can be reversed by 4-AP when it is administered at the time of respiratory arrest [Benton, B. J., Spriggs, D. L., Capacio, B. R. and Chang, F.-C. T. (1995) 4-Aminopyridine antagonizes the lethal effects of saxitoxin (STX) and tetrodotoxin (TTX). International Society of Toxicology, 5th Pan American Symposium on Animal, Plant and Microbial Toxins, Frederick, MD. July/August 1995, p. 217]. The purpose of this study was to determine whether 4-AP's efficacy could be enhanced further when administered at different times relative to STX intoxication. The animals used in this study were chronically instrumented for concurrent recordings of diaphragm electromyogram (DEMG), neck skeletal muscle electromyogram, Lead II electrocardiogram, and electrocorticogram (ECoG). There were five groups of unanesthetized guinea pigs. The first group served as 4-AP controls and received a 2 mg/kg i.m. dose of 4-AP. The four remaining groups were given a lethal dose of STX (5 microg/kg i.m.); the second group, STX controls, received no 4-AP; the third group, the 4-AP treatment group, received 4-AP immediately following cardiorespiratory collapse; the fourth group was the 4-AP/STX co-administration group and 4-AP was given concurrently with STX; and the fifth group was the 4-AP pretreatment group in which 4-AP was given 10 min before STX. At the point of STX-induced cardiorespiratory collapse, the guinea pigs were ventilated and given an i.p. injection of sodium bicarbonate. Results showed that 4-AP prevented cardiorespiratory collapse in 3/7 animals in the 4-AP pretreatment group. Also, 4-AP in conjunction with artificial ventilation and sodium bicarbonate accelerated recovery from STX-induced cardiorespiratory collapse in all the treatment groups compared to the STX controls.

Evidence for arylamine N-acetyltransferase activity in the Escherichia coli

N-Acetyltransferase activities with p-aminobenzoic acid and 2-aminofluorene as substrates were determined in isolates of the bacterium Escherichia coli. The N-acetyltransferase activity was determined by an acetyl CoA recycling assay and high pressure liquid chromatography. The N-acetyltransferase activities from a number of E. coli isolates were found to be 0.67 +/- 0.04 nmole/min/mg protein for 2-aminofluorene, and 0.46 +/- 0.02 nmole/min/mg protein for p-aminobenzoic acid. The apparent Km and Vmax values obtained were 2. 85 +/- 0.65 mM and 7.51 +/- 0.86 nmol/min/mg protein, respectively, for 2-aminofluorene, and 2.35 +/- 0.39 mM and 9.43 +/- 0.78 nmol/min/mg protein, respectively, for p-aminobenzoic acid. The optimal pH value for the enzyme activity was 7.0 for both substrates tested. The optimal temperature for enzyme activity was 37 degrees C for both substrates. The N-acetyltransferase activity was inhibited by iodoacetamide: at 0.25 mM iodoacetamide, activity was reduced 50%, and at 1.0 mM, more than 90%. Among a series of divalent cations and salts, Cu2+ and Zn2+ were demonstrated to be the most potent inhibitors. This report is the first demonstration of acetyl CoA:arylamine N-acetyltransferase activity in E. coli.

Sonographic examination of abdominal trauma by senior surgical residents

The focused ultrasound examination is assuming an important role in the evaluation of abdominal trauma. We evaluated the ability of senior surgical residents to independently use this technique. We also evaluated the efficacy of a single sonographic examination instead of serial examinations. Senior surgical residents underwent sonography instruction by two attending surgeons certified in the technique. Once proficiency was attained, a single sonographic examination was performed on patients with abdominal trauma triaged to a Level I trauma center. Residents obtained additional diagnostic studies deemed appropriate. Ultrasound results were compared with other diagnostic studies and clinical course. Sonography was performed on 518 patients between January 10, 1995 and June 30, 1996. Mechanism of injury was blunt in 92 per cent of patients and penetrating in 8 per cent. There were 22 true positives, 12 false positives, 8 false negatives, and 476 true negatives. Five of the eight false negatives were secondary to limited hollow viscus injuries with minimal associated intraperitoneal fluid. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 73.3, 97.5, 96.1, 64.7, and 98.3 per cent, respectively. The use of computed tomography and diagnostic peritoneal lavage decreased from 25 to 18 per cent and 3.2 to 0.2 per cent, respectively, as diagnostic tools. We conclude that surgical residents can competently perform trauma ultrasound. A single sonographic examination is effective and reliable. Sonography has essentially replaced diagnostic peritoneal lavage in our institution.

Antagonism of soman-induced convulsions by midazolam, diazepam and scopolamine

The effects of midazolam (MDZ), diazepam (DZ) and scopolamine (SCP) therapies on soman-induced electrocorticogram (ECoG) and biceps femoris electromyogram (EMG) activities and brain lesions were assessed in male rats. Animals received pyridostigmine (26 micrograms/kg, im) 30 min before soman (87.1 micrograms/kg, im) followed by therapy consisting of atropine (1.5 mg/kg) admixed with 2-PAM (25 mg/kg, im) 1 min later; MDZ (0.5 mg/kg), DZ (1.77 mg/kg) or SCP (0.43 mg/kg) was administered im at 1 min after the onset of convulsions (CVs). Typically, within 5 min after soman the ECoG profile changed to a full-blown, spike-and-dome epileptiform (SDE) pattern followed by CVs and increased amplitude of EMG activity. Treatment with SCP restored ECoG and EMG profiles by 30 min. At 2 hr after exposure only 1 animal demonstrated a slight abnormality in ECoG activity which was normal at 24 hr. Similarly, DZ and MDZ restored EcoG and EMG profiles by 30 min; however, in contrast to SCP, 83% of the animals demonstrated reappearance of SDE 2 hrs after soman. SCP therapy also enabled rats to move about in their cages by 30 min post treatment. In contrast, DZ- and MDZ-treated rats remained incapacitated as late as 2 hr post-exposure. Animals were euthanized at 24 hr, and the extent of soman-induced brain lesions was determined by light microscopic analysis. When present, brain lesions were minimal in SCP-treated rats. The mean brain lesion scores across all experimental conditions ranked as follows: soman control > MDZ > DZ > or = SCP = saline control. These observations suggest that SCP may be highly effective in severe soman intoxication.

Pharmacokinetics and pharmacodynamics of 4-aminopyridine in awake guinea pigs

The selective blockade of potassium channels on excitable membranes by 4-aminopyridine (4-AP) leads to facilitation of neurotransmitter release at a wide variety of synapses. This compound has been shown to be efficacious against lethality induced by saxitoxin (STX) and tetrodotoxin (TTX) in guinea pigs. To characterize the actions of 4-AP in guinea pigs we have investigated its pharmacokinetics (PK) and pharmacodynamics following a 2 mg/kg, intramuscular (im) dose in awake chronically instrumented (IN) animals. Animals were chronically instrumented for electrophysiologic recordings of diaphragmatic electromyogram (DEMG), lead II electrocardiogram (ECGII) and electrocorticogram (ECoG). Also, PK studies were carried out in uninstrumented (UN) guinea pigs. Blood and electrophysiologic data were collected at predetermined time intervals up to 4 hours post 4-AP administration. High performance liquid chromatography was used to determine plasma 4-AP concentrations. For IN and UN animals, plasma concentration-time data best fit a one-compartment model, and PK parameter estimates were similar for both groups. Peak plasma levels were found to occur between 16 and 17 min, and the half-lives of elimination were 65 and 71 min for IN and UN animals respectively. Heart and respiratory rates were elevated as early as 5 and 15 min respectively in response to 4-AP administration. The duration of action was approximately 1-1.5 half-lives of elimination beyond peak plasma levels. Maximum ECoG responses were observed between 12-15 min after 4-AP injection; some residual drug effects were still apparent at 240 min. The difference between the heart and respiratory rates and ECoG profiles suggests that these different physiological systems respond with varying degrees of sensitivity to plasma 4-AP concentrations. The stimulation of these systems is consistent with the action of 4-AP in reversing STX- and TTX-induced cardiorespiratory depression and decreased ECoG power in guinea pigs.

Arylamine N-acetyltransferase activity in Staphylococcus aureus

N-Acetyltransferase (NAT) activities were determined by incubation of Staphylococcus aureus cytosols with p-aminobenzoic acid (PABA) or 2-aminofluorene (2-AF) followed by high pressure liquid chromatography assays. The NAT activities from S. aureus were found to be 0.67 +/- 0.04 nmol/min/mg protein for the acetylation of 2-AF and 0.46 +/- 0.02 nmol/min/mg protein for the acetylation of PABA. The apparent K(m) and Vmax values obtained were 2.85 +/- 0.65 mM and 7.51 +/- 0.86 nmol/min/mg protein for 2-AF, and 2.35 +/- 0.39 mM and 9.43 +/- 0.78 nmol/min/mg protein for PABA, respectively. The optimal pH value for the enzyme activity was 7.0 for both substrates tested. The optimal temperature for enzyme activity was 37 degrees C for both substrates. The NAT activity was inhibited by iodoacetamide at 0.25 mM, and activity was reduced 50%. At 1.0 mM iodoacetamide activity was inhibited more than 90%. Among a series of divalent cations and salts, Zn2+, Ca2+, and Fe2+ were demonstrated to be the most potent inhibitors. The molecular weight of NAT from S. aureus was found to be 44.9 kDa. This report is the first demonstration of acetyl CoA: arylamine NAT activity in S. aureus.

Regulation of oxidation-reduction potentials through redox-linked ionization in the Y98H mutant of the Desulfovibrio vulgaris [Hildenborough] flavodoxin: direct proton nuclear magnetic resonance spectroscopic evidence for the redox-dependent shift in the pKa of Histidine-98

Flavodoxin from Desulfovibrio vulgaris is a low molecular weight (15 000 Da) acidic flavoprotein that contains a single flavin mononucleotide (FMN) cofactor. A distinguishing feature of the flavodoxin family is the exceptionally low midpoint potential of the semiquinone/hydroquinone couple. Tyrosine-98, which flanks the outer or si face of the FMN, plays an important role in establishing the oxidation-reduction properties of the bound cofactor as demonstrated by the substitution of a number of amino acids at this position [Swenson, R. P., & Krey, G. D. (1994) Biochemistry 33, 8505-8514]. The midpoint potential for the semiquinone/hydroquinone couple increases substantially when basic residues are introduced at this position. The pH dependency in the Y98H mutant is consistent with a redox-linked ionization model in which the favorable electrostatic coupling between the imidazolium cation and the flavin hydroquinone anion is responsible for the higher potential. Such a model predicts an increase in the pKa of 1.5 units for His98 upon complete reduction of the FMN. In this study, proton nuclear magnetic resonance spectroscopy was used to directly determine the intrinsic pKa of His98 as a function of the redox state of the cofactor in this flavodoxin. Values for the pKa of His98 in the oxidized and fully reduced flavodoxin are 7.02 +/- 0.08 and 8.43 +/- 0.11, respectively, an increase in the pKa by 1.41 units, which conforms with the previous prediction. These results provide direct experimental proof of the redox-linked ionization of this residue and provides further evidence of the crucial role of electrostatic interactions, in this case, in the stabilization of the flavin hydroquinone anion. This phenomenon may represent a general mechanism in the modulation of the reduction potential of the flavin cofactor within flavoenzymes in which ionizable groups such as histidine in the active center change ionization states during the catalytic cycle.

4-Aminopyridine reverses saxitoxin (STX)- and tetrodotoxin (TTX)-induced cardiorespiratory depression in chronically instrumented guinea pigs

The extent to which cardiorespiratory infirmity and other sublethal effects of saxitoxin (STX) and tetrodotoxin (TTX) can be reversed by 4-aminopyridine (4-AP) was investigated in guinea pigs chronically instrumented for the concurrent electrophysiological recordings of electrocorticogram (ECoG), diaphragmatic electromyogram (DEMG), Lead II electrocardiogram, and neck skeletal muscle electromyogram. Animals were intoxicated with either STX or TTX (2 and 3 microg/kg, im) to produce a state of progressive cardiorespiratory depression (depicted by decreasing DEMG amplitude, bradypnea, and bradycardia). At the point where cardiorespiratory performance was most seriously compromised (approximately 30 min posttoxin), 4-AP (1 or 2 mg/kg, im) was administered. The therapeutic effect of 4-AP was striking in that, within minutes, the toxin-induced diaphragmatic blockade, bradypnea, bradycardia, and depressed cortical activity were all restored to a level either comparable to, or surpassing, that of control. The optimal 4-AP dose level was determined to be 2 mg/kg (im) based on analyses of cardiorespiratory activity profiles throughout the course of intoxication and 4-AP treatment. At the dose levels (either 1 or 2 mg/kg) used to restore ventilatory function and cardiovascular performance, 4-AP produced no sign of seizures and convulsions. Although less serious secondary effects such as cortical excitant/arousal effect (indicated by ECoG power spectral analysis) and transient periods of skeletal muscle fasciculation were observed, these events were of minor concern particularly in view of the remarkable therapeutic effects of 4-AP.

Characterization of a lily tapetal transcript that shares sequence similarity with a class of intracellular pathogenesis-related (IPR) proteins

This study addresses isolating and characterizing a cDNA clone corresponding to a tapetum-specific transcript, designated as PR-10a from Lilium longiflorum. Anther ontogeny is histologically divided into three consecutive phases. The first encompasses early proliferative stages and differentiation of the locules. The second concerns microspore development from the onset of meiosis through microspore maturation. The final phase involves pollen maturation, originating with microspore mitosis through pollen formation. The lily PR-10a transcript is anther-specific and temporally expressed only at the phase of microspore development during which the tapetal cells become polarized, highly secretory, and exhibit loss of cell walls. The maximal level of PR-10a transcript coincides strictly with the peak of tapetal secretory function. Comparing mRNA and cDNA insert sizes reveals that PR-10a is close to full-length. Sequence analysis demonstrates similarity between the predicted lily PR-10a and asparagus AoPR1 protein, potato pSTH2 and pSTH21 proteins, parsley PcPR1 and PcPR3 proteins, bean PvPR1 and PvPR2 proteins, lupin L1R18B protein, pea 149 protein and a family of major allergens including Cor a 1 of hazel, Car b 1 of hornbeam, Aln g 1 of alder, Bet v 1 of birch and Api g 1 of celery. To the authors' knowledge, this is the first reported organ/tissue-specific IPR protein.

Nitrogen-rich silicon nitride thin films for deep-ultraviolet Mirau interferometry

We report experimental results on UV-transparent low-pressure chemical-vapor-deposition nitride thin films. We show that, by using nitrogen-rich rather than conventionally silicon-rich thin-film membranes, we are able to obtain more than 95% UV transparency below 250 nm, while keeping the stress of the membrane manageable and below standard nitride's giga-Pascal stress. Using these results, we were able to microfabricate a UV Mirau interferometer for correlation microscopy.

4-Aminopyridine antagonizes saxitoxin-and tetrodotoxin-induced cardiorespiratory depression

Antagonism of saxitoxin-and tetrodotoxin-induced lethality by 4-aminopyridine was studied in urethane-anesthetized guinea pigs instrumented for the concurrent recordings of medullary respiratory-related unit activities (Bötzinger complex and Nu. para-Ambiguus), diaphragmatic electromyogram, electrocorticogram, Lead II electrocardiogram, blood pressure, end-tidal CO2 and arterial O2/CO2/pH. The toxin (either saxitoxin or tetrodotoxin) was infused at a dose rate of 0.3 microgram/kg/min (i.v.) to produce a state of progressive cardiorespiratory depression. The animals were artificially ventilated when the magnitude of integrated diaphragm activities was reduced to 50% of control. Immediately after the disappearance of the diaphragm electromyogram, the toxin infusion was terminated, and 4-aminopyridine (2 mg/kg, i.v.) was administered. The therapeutic effect of 4-aminopyridine was striking in that the toxin-induced blockade of diaphragmatic neurotransmission, vascular hypotension, myocardial anomalies, bradycardia and aberrant discharge patterns of medullary respiratory-related neurons could all be promptly restored to a level comparable to that of control condition. The animals were typically able to breathe spontaneously within minutes after 4-aminopyridine. At the dose level used to achieve the desired therapeutic responses, 4-aminopyridine produced no sign of seizure and convulsion. Although less serious side-effects such as cortical excitant/arousal and transient periods of fascicular twitch could be observed, these events were of minor concern, in our opinion, particularly in view of the remarkable therapeutic effects of 4-aminopyridine.

A method for determining 4-aminopyridine in plasma: pharmacokinetics in anaesthetized guinea pigs after intravenous administration

An HPLC assay has been developed to measure 4-aminopyridine (4-AP) in guinea pig plasma. For the assay, all plasma samples (50 microL) were microfiltered following the addition of an internal standard (3,4-diaminopyridine). Filtrates (10 microL) were directly injected into a spherical silica column (100 x 2.1 mm; 5 microns); detection was achieved at 266 nm. Standard curves had correlation coefficients ranging from 0.9923 to 0.9992 and coefficients of variation expressed as a percentage (% CV) of below 8%. Precision was expressed as between-day and within-day variability of five test sample concentrations. Between-day % CV ranged from 4.0 to 6.5%. Within-day % CV ranged from 3.6 to 6.9%. Accuracy was assessed by examining expected within-day test sample concentrations against calculated concentrations; per cent errors were all below 10%. Stability studies demonstrated % CV below 5% after repeated freezing. The method was employed to study the pharmacokinetics of 4-AP after intravenous administration to anaesthetized guinea pigs. Serial blood samples (150 microL) were collected at predetermined time intervals up to 4 h post-4-AP (2 mg/kg, i.v.) administration. 4-AP demonstrated a biexponential decline in the plasma-concentration curve as a function of time indicating a two compartment model for this drug. Selected mean pharmacokinetic parameter estimates were alpha-half-life, 0.37 min; beta-half-life (biological half-life) for terminal slope, 109 min; and volume of distribution at steady state, 1036.18 mL/kg. 4-AP was found to rapidly and extensively partition into a peripheral tissue compartment and demonstrated a relatively long biological half-life. The findings from the current pharmacokinetic experiments support the pharmacology of 4-AP in its role for reversing saxitoxin (STX)- and tetrodotoxin (TTX)-induced diaphragmatic failure in terms of onset of action and duration of effect in anaesthetized guinea pigs.

Changing trends in the management of splenic injury

BACKGROUND

A gradual change in the management of splenic injuries has occurred at our institution. This study was therefore undertaken to determine whether changes in management of splenic injury influenced outcomes during the past 30 years.

PATIENTS AND METHODS

A retrospective study of patients admitted with splenic trauma between 1965 and 1994 was performed. Two hundred seven patients were identified and demographic and outcome data were recorded. Patients were then grouped based upon the period in which they received treatment (ie, Period I [1965 to 1974], Period II [1975 to 1984], and Period III [1985 to 1994]), and the type of treatment received (ie, splenectomy, splenorrhaphy, or observation).

RESULTS

More patients were treated in Period III than in the other two periods, and Period III patients had shorter hospital stays. Splenectomy was solely used during Period I; splenorrhaphy and observation were occasionally performed during Period II; and splenectomy, splenorrhaphy, and observation were performed in near-equal numbers during Period III. Mortality was similar for each period, though Injury Severity Scores (ISS) were higher during later years. When compared by treatment modality, patients receiving splenectomy had higher ISS and splenic injury classifications.

CONCLUSION

Patients treated by splenorrhaphy and observation for splenic injury have markedly increased over the past 30 years without adverse outcome.

PASG: does it help in the management of traumatic shock?

A prospective, randomized study was designed to determine the efficacy of pneumatic antishock garment (PASG) in the treatment of traumatic shock in a medium-size urban community. A total of 291 traumatic shock patients were assigned to either the PASG or No-PASG treatment groups. Of these, data from 248 patients were analyzed in detail. Analysis of demographic factors--such as age, sex, and mechanism of injury--as well as prehospital evaluative tools--such as trauma and CRAMS scores, and injury severity scores--revealed that the two groups were well-matched. This study did not demonstrate significant differences in hospital stay or mortality between PASG and No-PASG patients. Similarly, in the subset of patients with blunt trauma, PASG was not found to be beneficial.

Delayed hemothorax resulting from stab wounds to the internal mammary artery

Massive delayed hemothorax as a result of stab wounds to the internal mammary artery have not recently been reported. A patient who died after such an injury prompted a 10-year retrospective review. During that time period, 88 patients with stab wounds to the chest were identified. Thirty-five of these involved injuries to the parasternal region. This region is described as being located below the clavicles, between the midclavicular lines, and above the costal margins. We identified 5 patients with internal mammary artery injuries: 4 had massive delayed bleeding and 2 died. Our current recommendations for managing stable patients with parasternal stab wounds include maintaining a high index of suspicion, intensive care monitoring, and placement of chest tubes for monitoring. Should delayed bleeding occur, a prompt thoracotomy is mandatory.

Spontaneous recanalization of the esophagus after exclusion using nonabsorbable staples

Perforations of the thoracic esophagus can be fatal unless diagnosed promptly and treated effectively. Two patients in whom primary repair was not feasible were treated by esophageal exclusion and diversion using nonabsorbable stapling devices. Both patients had spontaneous recanalization of the esophagus without leakage or stricture formation. We conclude that nonabsorbable staples can be used safely to achieve effective esophageal exclusion, thereby allowing complete healing of the perforation. Furthermore, use of this technique may eliminate the necessity for another major procedure to reestablish esophageal continuity.

Potential bile acid metabolites. 23. Syntheses of 3-glucosides of nonamidated and glycine- and taurine-amidated bile acids

The 3-glucosides of nonamidated lithocholic, chenodeoxycholic, ursodeoxycholic, deoxycholic, and cholic acids, and their double conjugate forms with glycine and taurine were synthesized. The key reactions used were 1) beta-D- glucosidation at C-3 by the Koenigs-Knorr condensation reaction of 3 alpha-hydroxylated bile acid methyl (or p-nitrophenyl) esters with 1 alpha-bromo-1-deoxy-2, 3, 4, 6-tetra-O-acetyl-D-glucopyranose in the presence of cadmium carbonate in refluxing benzene; 2) indirect and direct amidations at C-24 by the activated p-nitrophenyl ester and by the diethylphosphorylcyanide methods, respectively, using glycinate ester and taurine as coupling agents; and 3) simultaneous alkaline hydrolysis of the hydroxyl-protecting and ester groups in both the sugar and aglycone moieties.

The involvement of metabotropic glutamate receptors in long-term depression of N-methyl-D-aspartate receptor-mediated synaptic potential in the rat hippocampus

The frequency-dependent long-term modifications of pharmacologically isolated N-methyl-D-aspartate (NMDA) receptor-mediated excitatory postsynaptic potential (EPSPNMDA) was studied. Intracellular recordings were obtained from CA1 cells of rat hippocampal slices and in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (10 microM) and bicuculline (20 microM) which block non-NMDA and GABAA receptors, respectively. Low-frequency stimulation at 5 Hz resulted in a long-term depression (LTD) of EPSPNMDA in 12 of 17 cells. However, when the stimulus frequency was increased to 30 Hz, a long-term potentiation (LTP) of EPSPNMDA was observed in 7 out of 9 cells. The LTD was not affected by pretreating the slices with okadaic acid (0.5-1 microM) suggesting that activation of endogenous protein phosphatase is not responsible for this process. In the presence of L-2-amino-3-phosphonopropionic acid (50 microM) or (RS)-alpha-methyl-4-carboxyphenylglycine (200 microM), 5 Hz tetanization resulted in LTP instead of LTD. These results suggest that activation of metabotropic glutamate receptor (mGluR) is necessary for the induction of EPSPNMDA LTD and blockade of mGluR unmasks a LTP.

Kansas surgeons' attitudes toward immediate breast reconstruction: a statewide survey

BACKGROUND

Immediate reconstruction following mastectomy provides patients the benefit of emerging from their operation with a reconstructed breast mound.

METHODS

A survey was distributed to 197 Kansas surgeons to determine the frequency of breast reconstruction and to identify factors that may influence them to refer patients for immediate reconstruction.

RESULTS

A response of 78.2% was obtained. Ten percent of mastectomy patients had breast reconstruction. Significant findings were that younger surgeons were more likely to discuss reconstruction with all patients and were more likely to preoperatively refer their patients to a plastic surgeon; surgeons in larger communities had more patients who had undergone immediate reconstruction; surgeons who discussed reconstruction with all patients had more patients who underwent immediate reconstruction; and frequency of immediate reconstruction increased along with increased time spent discussing reconstruction preoperatively.

CONCLUSION

Our survey indicated that immediate breast reconstruction was rarely performed; however, when it was, a number of factors were correlated. These included the surgeon's age and practice location, attitude toward reconstruction, and time spent preoperatively with patients.