Specialized intestinal metaplasia, dysplasia, and cancer of the esophagus and esophagogastric junction: prevalence and clinical data

BACKGROUND & AIMS

Adenocarcinoma of the esophagus and esophagogastric junction (EGJ) is increasing, the earliest lesion being specialized intestinal metaplasia (SIM). This study determined the prevalence and demographic features of patients with SIM, dysplasia, and cancer in the esophagus and EGJ.

METHODS

Two antegrade biopsy specimens were taken distal to the squamocolumnar junction (SCJ) and any tongues of pink mucosa proximal to the SCJ. Patients were categorized endoscopically and histologically as having long-segment (LSBE) or short-segment Barrett's esophagus (SSBE), EGJ-SIM, or a normal EGJ.

RESULTS

Of 889 patients studied, 56 were undergoing esophagoduodenoscopy screening or surveillance and were not included in the prevalence calculation. The overall prevalence of SIM was 13.2%, with 1.6% LSBE, 6.0% SSBE, and 5.6% EGJ-SIM. Dysplasia or cancer was noted in 31% of LSBE, 10% of SSBE, and 6.4% of EGJ-SIM patients (P </= 0.043). Two cancers were associated with LSBE, 1 with SSBE, and 1 with EGJ-SIM. Patients with LSBE and SSBE were predominantly white (P </= 0.001), male (P </= 0. 009), and smokers (P </= 0.004), with LSBE patients having a longer history of heartburn (P </= 0.009). In contrast, patients with EGJ-SIM were similar in gender and ethnicity to the reference group, tended to be older (P </= 0.05), drank less alcohol (P </= 0.02), and had a higher prevalence of Helicobacter pylori infection (P </= 0.05).

CONCLUSIONS

The prevalence of SSBE and EGJ-SIM is similar, but each entity is 3.5 times more prevalent than LSBE. However, the prevalence of dysplasia in LSBE is 2 times greater than in SSBE and 4 times greater than in EGJ-SIM. Demographically, EGJ-SIM patients are different from patients with Barrett's esophagus and have a higher prevalence of H. pylori infection. These data help to explain the increasing incidence of adenocarcinoma of the distal esophagus and EGJ.

Cadherin-5 redistribution at sites of TNF-alpha and IFN-gamma-induced permeability in mesenteric venules

The response of the endothelial permeability barrier in microvascular networks of the rat mesentery to perfused immune inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) was examined. TNF-alpha (12.5 U/ml) treatment did not change albumin permeability, but in combination with IFN-gamma (20 U/ml), there was a marked increase in the number of sites of extravascular albumin in postcapillary venules. Endothelial integrity was characterized by cadherin-5 immunoreactivity, which was localized to the continuous intercellular junctions of endothelium in arterioles, capillaries, and venules. Perfusion with the combined cytokines showed that the increased albumin permeability was dose dependent and correlated with the focal disorganization of cadherin-5 at intercellular junctions of venular endothelium. No correlation was found between the increase in albumin permeability and the localization of intravascular leukocytes or extravascular mast cells. These results show that the combination of TNF-alpha and IFN-gamma induces an endothelial phenotype with focal loss of cadherin-5 intercellular adhesion, which, in part, facilitates passage of blood macromolecules and cells to the interstitium.

Esophagogastric fistula: a complication of Crohn's disease--case report and review of the literature

Esophagogastric fistula formation as a complication of esophageal Crohn's has been reported in only one case in the literature. In addition, only eight cases of esophageal fistulae of any type have been reported in the setting of Crohn's disease. Unlike the more often described superficial, aphthous disease of the esophagus, response of fistulae to medical therapy has been disappointing, and recurrence and progression are likely. Surgery remains the primary modality for refractory disease. The roles of salicylates, antibiotics, immunosuppressive agents, sealants, and intralesional steroid injections have not been well defined. We present a case of severe, refractory Crohn's disease with fistula formation between the esophagus and stomach, and concomitant involvement of the oropharynx, duodenum, terminal ileum, and cecum.

Requirement of protein synthesis for group I mGluR-mediated induction of epileptiform discharges

Picrotoxin (50 microM) elicited rhythmic synchronized bursting in CA3 pyramidal cells in guinea pig hippocampal slices. Addition of the selective group I metabotropic glutamate receptor (mGluR) agonist (S)-3,5-dihydroxyphenylglycine (25 microM) elicited an increase in burst frequency. This was soon followed by a slowly progressive increase in burst duration (BD), converting the brief 250-520 ms picrotoxin-induced synchronized bursts into prolonged discharges of 1-5 s in duration. BD was significantly increased within 60 min and reached a maximum after 2-2.5 h of agonist exposure. The protein synthesis inhibitors anisomycin (15 microM) or cycloheximide (25 microM) significantly impeded the mGluR-mediated development of the prolonged bursts; 90-120 min of agonist application failed to elicit the expected burst prolongation. By contrast, the mGluR-mediated enhancement of burst frequency progressed unimpeded. Furthermore, protein synthesis inhibitors had no significant effect on the frequency or duration of fully developed mGluR-induced prolonged discharges. These results suggest that the group I mGluR-mediated prolongation of synchronized bursts has a protein synthesis-dependent mechanism.

Esophageal manometry and ambulatory 24-hour pH monitoring in patients with short and long segment Barrett's esophagus

OBJECTIVE

Short segment Barrett's esophagus (SSBE) is defined as the presence of specialized intestinal metaplasia (SIM) in the distal 2-3 cm of the esophagus. Although gastroesophageal reflux and heartburn is very common in these patients, the pathophysiology of the development of a short segment of SIM versus a longer segment of Barrett's epithelium is not clear. The aim of this study was to assess the extent of gastroesophageal reflux in short versus long segments of SIM.

METHODS

Of 203 consecutive patients undergoing endoscopy with two biopsies performed just distal to the squamocolumnar junction, 28 patients were identified as having SSBE as evidenced by SIM on biopsy. Twenty-two SSBE patients underwent esophageal manometry and 24-h dual pH monitoring, and the results were compared with 18 long segment Barrett's esophagus (LSBE) patients and 15 patients with normal 24-h pH studies.

RESULTS

SSBE and LSBE patients were significantly older than normal subjects (p < 0.0001). Also, lower esophageal sphincter pressure was significantly greater in SSBE patients compared with LSBE patients (12.3 +/- 1.6 vs 5.2 +/- 1.0 mm Hg,p < 0.0008). LSBE patients had a significantly lower distal esophageal peristaltic amplitude as compared with normals (p < 0.012). At 5 cm proximal to the LES, SSBE patients had significantly lower total 24-h pH scores, percent upright and percent supine reflux as compared with LSBE patients. Similarly, when measured at the proximal LES (0 cm), SSBE patients had significantly lower 24-h pH scores when compared with LSBE patients (p < 0.03), whereas percent upright and percent supine reflux were not significantly different. Both LSBE and SSBE patients had a greater degree of GER measured at 5 cm above and just proximal to the LES when compared with normals.

CONCLUSION

As a group, SSBE patients have more competent LES sphincters and less gastroesophageal reflux at 0 and 5 cm above the LES as compared with patients with LSBE. These data indicate that the degree and length of acid exposure in the esophagus are important factors in the pathogenesis of SIM involvement of the esophagus.

The value of screening for psychiatric disorders prior to upper endoscopy

Gastrointestinal (GI) complaints are among the most common symptoms in primary care yet are frequently unexplained and often lead to costly diagnostic testing. We sought to determine the prevalence of psychiatric disorders in patients with unexplained GI complaints undergoing upper endoscopy, and the likelihood of endoscopic abnormalities in patients with and without psychiatric diagnoses. We prospectively evaluated 116 adult patients who were undergoing upper endoscopy to evaluate GI complaints. All subjects received a structured psychiatric interview prior to endoscopy using PRIME-MD, and endoscopists were blinded to the PRIME-MD results. Psychiatric disorders were detected in 70 (60%) patients. Overall, there were 113 diagnoses (some patients had multiple disorders) with the most common being somatoform (44%), depressive (29%), and anxiety (19%) disorders. Only 29 patients had major endoscopic abnormalities, including esophageal disease (14), peptic ulcer (9), severe gastritis (4), gastric cancer (1), and esophageal cancer (1). There was a much higher prevalence of psychiatric disorders in patients without major endoscopic abnormalities (74% vs. 21%, p < 0.0001). Psychiatric disease was strongly predictive of endoscopic findings (OR for major abnormality = 0.11 in women, and 0.40 in men), especially if somatoform disorder was present (OR = 0.15). We conclude that, with a simple questionnaire, psychiatric disorders can be diagnosed in a large proportion of patients with unexplained GI complaints who are referred for upper endoscopy. The presence of a psychiatric disorder, particularly if somatoform, makes it unlikely that endoscopy will reveal significant GI disease.

Zn2+ blocks the NMDA- and Ca2+ -triggered postexposure current ipe in hippocampal pyramidal cells

Whole cell voltage-clamp recordings from acutely isolated hippocampal CA1 pyramidal cells from adult guinea pigs were used to evaluate divalent cations as possible blockers of the postexposure current (Ipe). Ipe is a cation current that is triggered by the rise in intracellular Ca2+ concentration that occurs after the application of a toxic level of N-methyl-D-aspartate (NMDA). Once triggered, Ipe continues to grow until death of the neuron occurs. Ipe may be a critical link between transient NMDA exposure and cell death. Ipe was blocked by micromolar concentrations of Zn2+. The Zn2+ effect had an IC50 of 64 microM and saturated at 500 microM. Prolonged Zn2+ block of Ipe revealed that the maintenance of a steady Ipe is not dependent on Ipe-mediated Ca2+ influx but that the continuous growth in Ipe is dependent on Ipe-mediated Ca2+ influx. The availability of an effective blocker of Ipe should facilitate the investigation of the intracellular activation pathway of Ipe and the role of Ipe in neuronal death.

Heterogeneity of polarographic oxygen tension measurements in cervix cancer: an evaluation of within and between tumor variability, probe position, and track depth

PURPOSE

To evaluate the heterogeneity of cervix cancer oxygenation as measured using the Eppendorf polarographic electrode and define the optimal number of measurements required to adequately sample a cervix cancer.

METHODS AND MATERIALS

Two to 6 tracks with 20-30 measurements per track were obtained in each of the 44 patients evaluated. One hundred sixty-eight tracks and 4719 measurements formed the basis of this analysis. Median pO2 and hypoxic proportion (HP5), defined as the percentage of pO2 values <5 mmHg, were calculated for each track and for each tumor. Within-tumor (W) and between-tumor (B) variability in oxygenation was evaluated using a variance component analysis. The standard error of the measured HP5 with each additional track in each patient was analysed as a function of the total number of tracks.

RESULTS

The ratio W/W + B was 0.67 and 0.76 for median pO2 and HP5, respectively, indicating that multiple measurements are needed to adequately sample a tumor. The median value of the standard error of the HP5 decreased from 7.0 to 4.0% from the first to the fifth track, respectively. It was estimated that adding the sixth track would only result in a small change (<0.3%) in the standard error. There was no significant difference in oxygen tension measurements as a function of the location of the measurements around the circumference of the cervix or the depth along the measurement tracks.

CONCLUSIONS

There is significant within tumor variability in oxygen tension in cervix cancer. Five tracks with 20-30 measurements per track is optimal to sample the oxygenation status of a cervix cancer. The present data does not suggest that there is a significant difference related to the position in the tumor at which the pO2 measurements were taken.

Role of group I metabotropic glutamate receptors in the patterning of epileptiform activities in vitro

In guinea pig hippocampal slices, picrotoxin elicited spontaneous epileptiform bursts 300-550 ms in duration. Additional application of (R,S)-3,5-dihydroxyphenylglycine or (S)-3-hydroxyphenylglycine, agonists specific for group I metabotropic glutamate receptors (mGluRs), or (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid, a broad-spectrum mGluR agonist, converted picrotoxin-induced interictal bursts into prolonged discharges measured on the order of seconds. The prolonged discharges induced by selective group I mGluR agonist continued to be produced for hours after agonist removal. The antagonists (S)-4-carboxyphenylglycine and (+)-alpha-methyl-4-carboxyphenylglycine had no effect on the duration of picrotoxin-induced interictal bursts. However, after agonist exposure, the persistent prolonged discharges occurring in the absence of agonist were reversibly suppressed by the antagonists, suggesting that the activity is maintained via endogenous activation of group I mGluRs by synaptically released glutamate. Our results suggest that, under some conditions, activation of group I mGluRs produces long-lasting enhancement of synaptic responses, mediated at least in part by autopotentiation of the group I mGluR response itself, which may result in the production of seizure discharges and contribute to epileptogenesis.

Secondary activation of a cation conductance is responsible for NMDA toxicity in acutely isolated hippocampal neurons

One of the key questions concerning glutamate toxicity is how a transient NMDA exposure can lead to a delayed death of neurons. To address this issue, we performed whole-cell recording on acutely isolated hippocampal CA1 neurons to monitor the membrane response after NMDA exposure. Transient NMDA exposure (100 microM, 10 min) induced an inward current (postexposure current; Ipe) which was associated with a Ca2+- and Na+-permeable cation conductance. Ipe continuously increased (in the absence of NMDA) until death of the neuron occurred. Application of NMDA in the absence of extracellular calcium failed to trigger Ipe and neuronal death. Postexposure suppression of Ipe protected against NMDA toxicity. These results indicate that a cation current, which is induced by an increase in intracellular calcium concentration ([Ca2+]i) and is itself partly carried by Ca2+, links the initial NMDA exposure to neuronal death.

Analysis of gunshot residues on human tissues and clothing by X-ray microfluorescence

The analysis of gunshot residues on human tissues and clothing in suicide, homicide, suspicious death, or attempted murder events, permits the forensic scientist to confirm the possibility of an entry wound caused by a gunshot bullet from a pistol, revolver, rifle, etc. The residues to be detected are lead (Pb), antimony (Sb), barium (Ba) usually from the primer, copper (Cu) and zinc (Zn) usually from the metal jacket bullet and iron (Fe) possibly from the barrel of the gun used. The presence or absence of these elements and their relative concentrations can help in the interpretation of the event.

The depolarizing GABA response

In some situations the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) elicits a hyperpolarizing response (H response) followed by a depolarizing response (D response) on cortical neurons. It has recently been established that the D response on hippocampal pyramidal cells is largely carried by bicarbonate ions (HCO3-). However, there is still controversy over whether the hyperpolarizing and depolarizing responses to GABA are mediated by the same receptor channel. A relatively new single receptor channel model proposes that the D response appears because chloride (Cl-) accumulates as a results of the Cl(-)-HCO3- conductance mediating the GABA response, dissipating the Cl- driving force and unmasking a net inward HCO3- current. This chloride accumulation model has gained favor because it provides an explanation for why higher concentrations of GABA are required to elicit the D response and why the D response generally follows an H response. On the other hand, there are some data that are best explained if there are two separate types of receptor channels mediating the H and D responses. This paper presents evidence for and against both the chloride accumulation hypothesis and the two different receptor channels hypothesis in the hope that investigators will recognize that this key problem concerning the generation of the D response remains unsolved.

A new probable increasing cause of esophageal ulceration: alendronate

We present a case of esophageal ulcerations caused by alendronate (Fosamax), a recently marketed medication. The patient presented with a chief complaint of retrosternal pain and severe odynophagia of 5 days duration. She was taking prednisone 10 mg and azathioprine 100 mg p.o. q.d. for systemic lupus erythematosus. To prevent osteoporosis, she was started on alendronate 10 mg q.d. 2 wk before her symptoms started. Endoscopy of the upper GI tract revealed two deep, large ulcers at the gastroesophageal junction. Multiple biopsy specimens revealed necroinflammatory debris and acute esophagitis. However, no organisms were identified, and the result of her HIV test (ELISA) was negative. Alendronate was discontinued, and her symptoms resolved completely in 1 wk. Follow-up endoscopy performed 4 wk later revealed complete healing of the ulcers.

Ionic basis of the postsynaptic depolarizing GABA response in hippocampal pyramidal cells

1. Whole cell voltage-clamp recording with recording pipette solutions of differing ionic composition was used to determine the ionic basis of the depolarizing gamma-aminobutyric acid (GABA) response. In the presence of 4-aminopyridine and excitatory amino acid receptor blockers, giant GABA-mediated postsynaptic currents (GPSCs) were recorded from CA3 pyramidal neurons in hippocampal slices from adult guinea pigs. With the GABAB component blocked, the GPSC was composed of an initial outward current (GABAA component) that peaked at 115 ms followed by a late inward current (GABAD component) that peaked at 400-600 ms. 2. Reduction of the intracellular concentration of potassium ([K+]i)resulted in no significant change in the reversal potential of the GABAD component of the GPSC, indicating that it is not a nonspecific cation current. 3. The HCO3- permeability of the channel mediating the GABAD response was assessed by using recording pipette solutions containing three different concentrations of bicarbonate ([HCO3-], 19, 49, and 102 mM). The reversal potential of the GABAD response shifted in the depolarizing direction as the HCO3- equilibrium potential was shifted in the depolarizing direction, indicating that the channel mediating the GABAD response is permeable to HCO3-. The reversal potential of the GABAD response was more sensitive to changes in recording pipette [HCO3-] than the reversal potential of the GABAA response, indicating that the GABAD response is carried by HCO3- to a greater extent than the GABAA response. 4. The outward current-inward current sequence of the biphasic GPSC was reversed to an inward current-outward current sequence by using a high [Cl-]/low [HCO3-] recording pipette solution (40 mM Cl-/6 mM HCO3-), indicating that the GABAA component is more sensitive to changes in [Cl-]i, and the GABAD component is more sensitive to changes in [HCO3-]i. 5. These data indicate that the GABAD component of the GPSC is predominantly carried by HCO3-. While this result supports the recently propsed chloride accumulation model, the model in its present form cannot explain the inward current-outward current polarity sequence of the GPSC recorded with the high [Cl-]/low [HCO3-] intracellular solution. The data obtained using that solution reveal the need for a more expansive chloride accumulation/ depletion model or for a model utilizing two distinct ionotropic GABA channels with different anion permeability ratios to account for the biphasic nature of the GPSC.

Selective expression of transient outward currents in different types of acutely isolated hippocampal interneurons

1. Voltage-dependent outward currents in CA1 interneurons were studied with the use of whole cell voltage-clamp techniques. Tissue slices containing strata lacunosum-moleculare and radiatum (L-M-R regions) of the hippocampal CA1 region were prepared. Neurons were then isolated from these tissue slices with the use of an acute dissociation procedure. The morphologies of the isolated neurons were distinct from those of pyramidal cells and correlated with those of interneurons identified in the L-M-R regions after immunohistochemical stainings. 2. Total outward currents were elicited from the isolated cells by depolarization steps applied after a 300-ms hyperpolarization prepulse to 100 mV from a holding potential of 50 mV. Delayed outward currents were obtained by intercalating a 120-ms step at 55 mV between the hyperpolarizing prepulse and the depolarization. The intercalating step served to inactivate transient outward currents. Transient outward current were isolated by subtracting the delayed outward currents from the total outward currents. 3. Interneurons were subgrouped on the basis of their ability to produce transient outward current in response to the above protocol. 4. The two groups of interneurons possessed distinct morphological features. Cells producing transient outward currents had polygonal-shaped somata with thick primary processes that gave rise to smaller secondary processes at a short distance from the soma. Interneurons without activatable transient outward currents had somata that were not polygonal and they had more slender primary dendritic processes. 5. These results suggest that interneurons in the L-M-R regions can be divided into two groups on the basis of the presence or absence of voltage-dependent transient outward currents. The two groups of cells differentiated on this basis also have distinguishable morphological traits. The difference in the properties of the outward current may be a factor contributing to the variation in the firing pattern of recorded interneurons reported in previous studies.

Extracellular Mg2+ modulates intracellular Ca2+ in acutely isolated hippocampal CA1 pyramidal cells of the guinea-pig

Using digital imaging microscopy and fluorescent probes, isolated hippocampal CA1 pyramidal neurons of the guinea-pig were used to examine the roles of [Mg2+]o in regulation of [Ca2+]i and [Mg2+]i. Low extracellular Mg ([Mg2+]o) (0.3 mM) significantly increased [Ca2+]i compared to 1.2 and 4.8 mM [Mg2+]o. In contrast, [Mg2+]i levels remained relatively constant, irrespective of alterations of [Mg2+]o. The sustained rise in [Ca2+]i induced by low [Mg2+]o was reduced 70% by 1 microM verapamil and 42% by 1 mM Ni2+, and completely abolished by 5 mM Ni2+. The data suggest that [Mg2+]o regulates [Ca2+]i in hippocampal neurons, probably by modulating Ca2+ entry via voltage-sensitive Ca2+ channels, which may play important roles in epileptogenesis, memory, learning and brain trauma. Furthermore, the results demonstrate that intracellular Mg2+ concentration does not follow passively the concentration of Mg2+ in the extracellular solution.

Synchronized oscillations in hippocampal CA3 neurons induced by metabotropic glutamate receptor activation

The metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3 dicarboxylic acid (ACPD) at concentrations above 60 microM produced stereotypic oscillatory activity in CA3 pyramidal cells of rat hippocampal slices. This oscillatory activity consisted of trains of depolarizations with overriding action potentials. On average, individual trains lasted 7 sec and recurred at intervals of 24 sec. During each train, the constituent depolarizations achieved a maximum frequency of 27 Hz, then slowed to 8 Hz toward the end of the train. Extracellular and dual intracellular recordings suggested that this ACPD-induced oscillatory activity occurred synchronously in the CA3 population. The oscillations persisted in the presence of GABAA, GABAB, and NMDA receptor antagonists. In contrast, the oscillations were blocked by the AMPA/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 10-30 microM). Likewise, the oscillations were blocked by the metabotropic glutamate receptor antagonists (+)-alpha-methyl-4-carboxyphenylglycine [(+)-MCPG; 1 mM], (S)-4-carboxy-3-hydroxyphenylglycine [(S)-4C3HPG; 1mM] and (S)-4-carboxyphenylglycine [(S)-4CPG; 1 mM]. The results suggest that activation of metabotropic glutamate receptors can result in a permissive state that allows AMPA/kainate receptor-mediated conductances to mediate synchronized activity among hippocampal CA3 neurons.

Excitatory synaptic potentials dependent on metabotropic glutamate receptor activation in guinea-pig hippocampal pyramidal cells

1. Intracellular and extracellular recordings of CA1 and CA3 neurones were performed in guinea-pig hippocampal slices to examine synaptic activities dependent on metabotropic glutamate receptors (mGluRs). 2. Long burst activities were elicited by 4-aminopyridine in the presence of ionotropic glutamate receptor and GABAA receptor blockers (6-cyano-7-nitroquinoxaline-2,3-dione and 3-(RS-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid, and picrotoxin). Long bursts were also elicited by alpha-dendrotoxin. 3. Long bursts consisted of a 5-25 s depolarization with overriding action potentials and occurred rhythmically at intervals ranging from 1 to 20 min. Long bursts were generated in a population of CA3 neurones and the synchronized output elicited long bursts in CA1 cells. Depolarizing potentials underlying long bursts in CA1 cells had a reversal potential of -14.8 +/- 5.1 mV. 4. Long burst-associated depolarizations in CA1 neurones were suppressed by local application of L-(+)-2-amino-3-phosphonopropionic acid (L-AP3) and of the phenylglycine derivatives (+)-alpha-methyl-4-carboxyphenylglycine ((+)-MCPG), S-4-carboxyphenylglycine (S-4CPG) and S-4-carboxy-3-hydroxyphenylglycine (S-4C3HPG). (-)-MCPG or atropine application did not affect the long burst-associated depolarization. 5. Bath perfusion of (+)-MCPG (0.5 mM), S-4CPG (0.5 mM), S-4C3HPG (0.5 mM) or L-AP3 (1 mM) blocked the occurrence of long bursts. 6. The results suggest that the long burst-associated depolarizations are synaptic potentials dependent on mGluR activation. Activation of mGluRs may also be involved in the generation of synchronized long bursts in the CA3 region.

Role of metabotropic glutamate receptor subtypes in the patterning of epileptiform activities in vitro

1. Epileptiform activities were elicited from the in vitro guinea pig hippocampus by the addition of picrotoxin. Modification of the picrotoxin-induced activities by agents active at metabotropic glutamate receptors (mGluRs) was examined using intracellular and extracellular recordings. 2. Picrotoxin typically elicited synchronized discharges (epileptiform bursts) in CA3 neurons. These spontaneously occurred at regular intervals. In the presence of (+)-alpha-methyl-4-carboxyphenylglycine (MCPG; 700-1,000 microM), an antagonist at multiple mGluR subtypes, the frequency of spontaneous epileptiform bursts decreased. In contrast, when the mGluR agonists (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD; 5 microM) or (2S,3S,4S)-alpha-(carboxycyclopropyl)-glycine (L-CCG-I; 10 microM) were added to the incubating medium, the frequency of epileptiform bursts increased. No consistent change in membrane potential, burst duration, nor burst afterhyperpolarization was associated with the changes in burst frequency. 3. When spontaneous burst frequency was reduced in MCPG, stimulation at a higher frequency entrained bursts without failure. Bursts evoked in MCPG were similar in waveform and amplitude to those evoked in the control state. 4. (S)-4-carboxyphenylglycine (S-4CPG) and (R,S)-4-carboxy-3-hydroxyphenylglycine (RS-4C3HPG) are antagonists at mGluR subtypes 1 and 5 but agonists at mGluRs 2 and 3. Addition of either of these agents increased the frequency of epileptiform bursts. 5. These results suggest that sufficient glutamate is released during epileptiform activities to activate mGluRs. The overall effect is to increase the frequency of synchronized discharges. This modulatory action on burst frequency is probably mediated via the mGluR 2 and 3 receptor subclass.

A method allowing intracellular and extracellular single-unit recordings from brain slices in the grease-gap chamber

The grease-gap chamber makes it possible to perfuse two parts of a brain slice separately. Hence, it lies between bath application and iontophoresis or pressure ejection in terms of the size of the region that receives controlled drug dosing. Modifications of a commercially available chamber are described which have permitted the first extracellular and intracellular single-unit recordings to be taken from brain slices in a grease-gap preparation. In addition, we describe the electrical resistance of the gap as a measure of the integrity of the barrier and a simple method for monitoring this resistance continuously. The resistance monitor is particularly useful during low flow rate conditions that improve mechanical stability. These techniques extend the grease-gap method to electrophysiological studies of single cells in slices.

Analysis of 3,294 cases of upper gastrointestinal bleeding in military medical facilities

OBJECTIVES

Upper gastrointestinal bleeding (UGIB) remains a commonly encountered medical emergency with significant morbidity and mortality. Most large studies detailing the specific incidence, demographic, and mortality data were performed more than a decade ago. This study analyzes 3,294 cases of UGIB from 139 military medical treatment facilities over a 12-month period.

METHODS

A retrospective chart review of Department of Defense military medical treatment facilities for UGIB was performed from October 1990 through September 1991. Core data such as demographic information were analyzed, as well as specific data relating to UGIB.

RESULTS

The incidence of UGIB was 36 per 100,000 population with a male-to-female ratio of 2.18 and a mean age of 52 +/- 19.65 yr. The number of cases increased with age; 44.5% of all patients were > or = 60 yr old. The overall mortality was 7.0% (231 of 3294), and death rates were similar among males and females (7.1% vs. 6.8%) with an odds ratio of 1.03 (CI: 0.77-1.402). Mortality increased with age in both genders; 73.2% of deaths occurred in patients more than 60 yr old. Comorbid illness was noted in 50.9% (1675 of 3294) of patients, with similar occurrence in males (48.7%) and females (55.4%). One or more comorbid illnesses were noted in 98.3% of the patients who died, and in 72.3% of cases, they were the primary cause of death. Bleeding was the primary cause of death in 18.6% of patients. Upper endoscopy was performed in 68.8% of cases, therapeutic endoscopy in 12.6%, repeat endoscopy in 10.7%, and surgery in 4.4%. Blood transfusions were administered in 47.3% of cases, with most patients receiving < 5 units of blood. Rebleeding after initial hemostasis was noted in 7.1% of cases. Factors related to increased mortality include age > 60 (p < 0.001), transfusion requirement > 5 U (p < 0.001), presence of comorbid illness (p < 0.001), rebleeding after initial hemostasis (p < 0.005), surgery (p < 0.001), and UGIB occurring during hospitalization (p = 0.027).

CONCLUSIONS

We conclude: 1) The incidence of UGIB is 2-fold greater in males than in females, in all age groups; however, the death rate is similar in both sexes. 2) The mortality rate in this study is slightly lower than in most previous studies and may be more reflective of the average mortality in the community at large. 3) In UGIB patients, comorbid illness and not actual bleeding is the major cause of death. 4) Upper endoscopy was performed less often in this study than in other studies, and there were fewer blood transfusions; however, rebleeding and mortality rates remained similar.

Intracellular QX-314 blocks the hyperpolarization-activated inward current Iq in hippocampal CA1 pyramidal cells

1. Whole cell voltage-clamp recordings (access resistance < or = 12 M omega) from CA1 pyramidal cells in the guinea pig hippocampal slice revealed a hyperpolarization-activated inward current with an inward tail upon repolarization. The current activation range extended from approximately -50 mV to -130 mV, with half-activation at -86 mV. This current was identified as the q current (Iq). 2. Intracellular QX-314 (5 or 10 mM), a quaternary derivative of lidocaine, blocked Iq completely throughout its activation range. 3. There is a growing realization that Iq may be responsible for the pacemaker depolarization in cells that display rhythmic calcium spikes. Because QX-314 blocks Iq completely, it could be used to test whether Iq is essential to this oscillatory activity.

Suppression of a Ca2+ current by NMDA and intracellular Ca2+ in acutely isolated hippocampal neurons

1. Ca2+ current was examined in acutely isolated hippocampal cells with the use of whole cell voltage-clamp recording and under continuous intracellular perfusion. A persistent Ca2+ current was activated by depolarization to -10 mV from a holding potential of -50 mV. 2. The persistent Ca2+ current was suppressed upon a wash out of the intracellular Mg(2+)-ATP. Adenosine 3',5'-cyclic monophosphate (cAMP) introduced intracellularly potentiated the Ca2+ current, and kinase A inhibitor blocked the current. 3. Reversible suppression of the persistent Ca2+ current was also observed by elevating intracellular Ca2+. This Ca(2+)-dependent suppression was retarded by the addition of a phosphatase inhibitor, okadaic acid, to the intracellular solution. 4. N-methyl-D-aspartate (NMDA) elicited inward current (NMDA response) in the isolated cells. The persistent Ca2+ current was transiently suppressed after the NMDA response. Suppression of the Ca2+ current by NMDA was reduced when intracellular Ca2+ buffering capacity was increased by increasing the concentration of bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid (BAPTA) from a concentration of 1-10 mM. 5. Substitution of ATP in the intracellular solution with ATP-gamma-S or the addition of okadaic acid to the intracellular solution reduced the suppressive effect of NMDA on the Ca2+ current. 6. The results suggest that the persistent Ca2+ current in the hippocampal cells is maintained by a kinase A-mediated phosphorylation. Increases in the intracellular Ca2+ concentration suppressed the Ca2+ current via a mechanism involving a phosphatase. Ca2+ entry through the NMDA receptor channel suppressed the Ca2+ channel by activating the phosphatase.

Suppression of GABAA receptor responses by NMDA application in hippocampal neurones acutely isolated from the adult guinea-pig

1. In acutely isolated hippocampal cells, NMDA and glutamate application suppressed GABAA receptor-mediated responses. We studied the cellular events underlying the interaction between the two classes of receptors by using a whole-cell voltage-clamp approach. 2. Following an NMDA application, an outward current mediated by GABAA receptor activation (GABA response) was suppressed for up to 12 s. The suppression of the GABA response was reduced when Ca2+ in the extracellular solution was replaced by Ba2+ or when intracellular BAPTA (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) was increased from 1 to 10 mM. 3. Replacing ATP in the intracellular solution by adenosine-5'-O-3-thiotriphosphate reduced the suppressive effect of NMDA application on the GABA response. Okadaic acid, a phosphatase inhibitor, also prevented the NMDA-induced suppression of the GABA response. In addition, when the intracellular perfusing solution contained the calcineurin autoinhibitory fragment (50 microM), suppression of the GABA response by the NMDA current was also reduced. 4. Intracellular perfusion of an activated form of the Ca(2+)-dependent phosphatase, calcineurin, suppressed GABA responses. 5. The results show that NMDA responses elicited in hippocampal neurones transiently suppressed GABA responses. The data suggest that the functional linkage of the NMDA response with the GABA response was established via a Ca(2+)-dependent dephosphorylation process.

Benign colonic ulcers associated with nonsteroidal antiinflammatory drug ingestion

Nonsteroidal antiinflammatory drugs can be associated with benign colonic ulcers. The ulcers are easily diagnosed by colonoscopy, and, if uncomplicated, they are best treated by cessation of the nonsteroidal antiinflammatory drugs. Benign colonic ulcers should be included in the differential diagnosis of any patient who presents with gastrointestinal complaints and is taking nonsteroidal antiinflammatory drugs.

Recurrent clinical exacerbations of liver disease during the course of infection with hepatitis C virus

Symptomatic clinical relapses during the course of chronic hepatitis C virus (HCV) infection are uncommon. Furthermore, acute liver dysfunction with elevated bilirubin during alpha-interferon therapy without other apparent coexisting diagnoses is rare. The case of a 31-yr-old man with three clinical exacerbations of HCV infection over an 18-month period is described. The third episode was characterized by rising serum aminotransferase levels on alpha-interferon therapy. The precise cause of this patient's flares is unknown. An immunologically mediated clearance of the hepatitis C virus, mutation of HCV, or infection with different HCV viral strains are the leading possibilities.

Carbachol-induced synchronized rhythmic bursts in CA3 neurons of guinea pig hippocampus in vitro

1. Carbachol effects on CA3 hippocampal cells were studied in the absence of ionotropic glutamatergic and GABAergic transmission with intracellular and extracellular recordings from guinea pig septohippocampal slices. 2. In all experiments the perfusing solution contained ionotropic glutamate and gamma-aminobutyric acid (GABA) receptor blockers [6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10-20 microM), 3-((+/-)-2-carboxypiperazin-4-il)propyl-1-phosphonic acid (CPP, 10-20 microM), and picrotoxin (50 microM), respectively]. Under these conditions, the excitatory and early inhibitory postsynaptic potentials, evoked in CA3 pyramidal cells by mossy fiber stimulation before the addition of the blockers, were completely suppressed. 3. Carbachol (50 microM) introduced via bath perfusion or pulse application elicited a series of rhythmic bursts with overriding action potentials. Each rhythmic burst lasted up to 30 s and repeated at intervals of 0.7-6 min. Rhythmic bursts were blocked by atropine (1 microM). 4. At membrane potentials more depolarized than -70 mV, carbachol also elicited a sustained depolarization associated with an increase in membrane input resistance and action-potential firing. This response was blocked by atropine (1 microM). 5. Carbachol can induce both rhythmic bursts and sustained depolarizations in the same cell. Rhythmic bursts were elicited when the membrane potential of the cell was more hyperpolarized than -70 mV; sustained depolarizing responses were activated by carbachol when the cell membrane potential was more depolarized than -70 mV. 6. Extracellular field potential responses in the CA3 region occurred simultaneously with rhythmic bursts, indicating the synchronization of the event in the CA3 field. Dual intracellular recordings confirmed that rhythmic bursts occurred simultaneously in CA3 hippocampal pyramidal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Synchronization of inhibitory neurones in the guinea-pig hippocampus in vitro

1. Intracellular recordings were obtained from pyramidal, granule and hilar cells in transverse slices of guinea-pig hippocampus to examine synaptic interactions between GABAergic neurones. 2. In the presence of the convulsant compound 4-aminopyridine (4-AP), after fast excitatory amino acid (EAA) neurotransmission was blocked pharmacologically, large amplitude inhibitory postsynaptic potentials (IPSPs) occurred rhythmically (every 4-8 s) and synchronously in all principal cell populations (triphasic synchronized IPSPs). In the presence of the GABAA receptor blocker picrotoxin (PTX), a large amplitude IPSP continued to occur spontaneously in all principal cells simultaneously (monophasic synchronized IPSP). 3. Burst firing occurred simultaneously in a group of hilar neurones (synchronized bursting neurones) coincident with triphasic synchronized IPSPs in principal cells. After PTX was added, the bursts and the underlying depolarizing synaptic potentials were completely suppressed in some of the synchronized bursting neurones (type I hilar neurones), while others (type II hilar neurones) continued to fire in bursts coincident with monophasic synchronized IPSPs in principal cells. Intense hyperpolarization blocked burst firing and revealed underlying attenuated spikes of less than 10 mV, but did not uncover any underlying depolarizing synaptic potentials. 4. In type II hilar neurones, during sufficient hyperpolarization, spontaneous activity consisted of attenuated spikes. With depolarization, the small spikes began to trigger full size action potentials. These data suggest the presence of electrotonically remote spike initiation sites. 5. The morphology of synchronized bursting neurones was revealed by intracellular injection of the fluorescent dye Lucifer Yellow. Attempts to inject dye into one type II hilar neurone often resulted in the labelling of two to four cells (dye coupling). Dye coupling was not observed in type I hilar neurones. 6. These findings indicate that excitatory interactions synchronizing the firing of GABAergic neurones can occur in the absence of fast EAA neurotransmission. GABAergic neurones can become synchronized via their recurrent collaterals through the depolarizing action of synaptically activated GABAA receptors. In addition, a subpopulation of GABAergic neurones can become synchronized by a mechanism probably involving electrotonic coupling.

Differences in voltage-dependent sodium currents exhibited by superficial and deep layer neurons of guinea pig entorhinal cortex

1. Sodium currents were studied using whole-cell voltage-clamp techniques in neurons acutely isolated from superficial (II/III) and deep (V/VI) layers of guinea pig entorhinal cortex. 2. Sodium currents were larger (peak amplitude) in superficial than in deep layer cells under the same conditions: -1939 +/- 780 (SD) pA (N = 6) versus -307 +/- 257 pA (N = 6). Specific membrane conductance was calculated to be 12.3 +/- 9.6 mS/cm2 for superficial layer cells and 1.4 +/- 0.9 mS/cm2 for deep layer cells. 3. Sodium currents could be activated in superficial layer cells from potentials as depolarized as -20 mV, whereas no significant currents could be activated in deep neurons from potentials more depolarized than about -50 mV. Using a protocol consisting of a 25-ms prepulse and a 20 ms test pulse, the inactivation curves for superficial layer cells were found to be shifted toward more depolarized potentials by an average of 15 mV (V50 = -59.8 +/- 3.8 mV compared with -75.7 +/- 12.0 mV for deep cells). This produced a region of overlap with the activation curves for superficial cells. 4. Over a range of about -50 to -20 mV in superficial layer cells, the region of overlap of the activation and inactivation curves, a sodium current could be activated, which did not fully inactivate during the test pulse (average peak amplitude: -89.5 +/- 48.7 pA; crossover voltage: -39.2 +/- 2.0 mV). Voltage steps to more depolarized potentials, outside the voltage "window", permitted complete inactivation of the sodium current.(ABSTRACT TRUNCATED AT 250 WORDS)

Colocalization of nitric oxide synthase and somatostatin immunoreactivity in rat dentate hilar neurons

Distribution of nitric oxide synthase (NOS), somatostatin (SSN), and parvalbumin (PV) was studied in the rat hippocampus by immunohistochemical methods. The aim was to explore the interrelationship between SSN-immunoreactive (SSN-IR) neurons in the dentate hilus, which have been shown to be vulnerable to a number of pathophysiological insults, and the presence or absence of NOS and/or PV in the same subset of dentate hilar neurons. Small NOS-IR neurons were scattered in the pyramidal, oriens, and radiatum layers of the CA1-CA3 areas and in the subiculum, where larger NOS-IR neurons were occasionally noted. In the area dentata, NOS-IR neurons, which were composed of small and large polymorphic cells, appeared as a single file at the hilar border with the granule cell layer and clustered in the hilus in fairly high density. Double-labeling techniques showed that most NOS-IR neurons in the hilus were SSN-IR, whereas coexistence of NOS and PV immunoreactivity or SSN and PV immunoreactivity was low in dentate hilar neurons. In other areas of the hippocampus, colocalization of NOS and SSN in the same neurons was much less frequent. Thus, SSN-IR neurons in the dentate hilus constitute a population of neurons that contain the enzyme NOS as well. The presence of NOS coupled to the lack or low level of PV in this group of neurons may provide a neurochemical basis for their high susceptibility to certain pathophysiological insults.

Multiphasic desensitization of the GABAA receptor in outside-out patches

GABAA receptor function was studied in outside-out patches from guinea pig hippocampal neurons using a drug application system with an exchange time of under 1.5 ms. Application of GABA to these patches induced a Cl- conductance that desensitized with prolonged exposure. Increasing GABA concentrations induced larger conductance increases that were associated with more complex patterns of desensitization. Smaller GABA responses desensitized with monophasic kinetics, whereas large responses displayed bi- and triphasic kinetics. Desensitization of the response to 1 mM GABA was triphasic in about 70% of the patches (tau = 15.4, 207, and 1370 ms) and biphasic in about 30% of the patches (tau = 44 and 725 ms). All phases of desensitization reversed at the Cl- equilibrium potential. Over the concentration range from 3 microM to 3 mM, both the rate and the extent of desensitization increased; however, complete desensitization was rarely observed. The increase in desensitization rate was due to an increase in the relative contribution of the faster phases with increasing GABA. The time constants of the three phases were independent of concentration. The different phases are not mediated by separate receptor populations, because double pulse experiments demonstrated interconversion among the fastest phase and the two slower phases. We demonstrate the plausibility of a model in which multiphasic desensitization is a consequence of the faster association rate at higher GABA concentrations.

Superior mesenteric venous thrombosis masquerading as Crohn's disease

Superior mesenteric venous (SMV) thrombosis is an uncommon cause of mesenteric ischemia, frequently presenting with nonspecific and subacute symptoms. We report a case of a 28-yr-old man presenting with symptoms and radiographic changes suggestive of Crohn's disease who, upon further evaluation, was found to have SMV thrombosis. A search for a precipitating condition revealed a strong family history of thromboembolic disease and deficiency of protein C. The patient responded to supportive therapy and anticoagulation.

The effect of indomethacin on the secretion of human salivary epidermal growth factor

Ulceration associated with nonsteroidal anti-inflammatory drug (NSAID) use is a common problem in elderly patients. The postulated cause of NSAID ulceration is multifactorial but is probably related to the inhibition of the cyclo-oxygenase pathway and a subsequent decrease in mucosal prostaglandin levels. Epidermal growth factor (EGF), on the other hand, has been shown to be gastroprotective, stimulating DNA synthesis, and preventing ASA-induced gastric ulceration. Since EGF is important in gastric mucosal protection, we questioned whether the potential ulcerogenic properties of indomethacin were related in part to decreasing salivary EGF. Twenty healthy male volunteers with no gastrointestinal complaints received indomethacin 50 mg P.O. t.i.d. for 3 consecutive days. Saliva and serum were collected before indomethacin treatment and repeated 2 h after the last indomethacin dose. Stimulated salivary samples were collected for 15 min in fasted subjects and assayed for EGF, whereas serum indomethacin levels were determined by high-performance liquid chromatography. EGF levels significantly decreased by 33% after indomethacin (p < 0.03), and this decrement was linearly related to serum indomethacin concentrations (r = 0.58; p < 0.048). Salivary output did not change after indomethacin treatment. Based on this data, we concluded that indomethacin's ulcerogenic properties may be related to its prostaglandin inhibitory properties as well as its ability to decrease salivary EGF output.

Diffusion versus iontophoresis in the transport of gentamicin in the burned rabbit ear model

This experimental study demonstrates that iontophoresis can be used to transport biologically active gentamicin into auricular cartilage. Fifty female New Zealand White rabbits were divided into three groups: live controls with unburned ears, live animals with burn-injured ears (deep or partial-thickness), and euthanized animals with unburned ears. Each group was then divided into subgroups that received gentamicin transported by iontophoresis or diffusion. In ears subjected to iontophoresis, adequate gentamicin activity could be demonstrated only in the cartilage of euthanized animals with unburned ears and live animals with full-thickness burned ears. Diffusion did not transport a detectable level of gentamicin in any instance. Diffusion is ineffective in the transport of gentamicin and should not be used as a primary method of treatment for ear chondritis. Iontophoresis did not transport active gentamicin across partial-thickness burns, presumably because the migrating antibiotic molecules were dispersed throughout the body by the circulation. However, if the circulation is destroyed, as in a full-thickness burn, iontophoresis can move the biologically active gentamicin into the cartilage.

Informatics in medical practice: billing systems survey by the Hawaii Medical Association

The Information Age has arrived! Our offices are quickly integrating information machines for the business part of our profession, just as the stethoscope and scalpel are requisites for the practice of medicine and surgery. The mission of the HMA Computer Committee is to provide guidance in the direction of medical informatics for its members. We hope to assist the membership in the selection, evaluation and use of the products relating to the processing of information in the modern practice of medicine.

Synaptic modifications accompanying epileptogenesis in vitro: long-term depression of GABA-mediated inhibition

We used an in vitro model similar to kindling to examine the processes underlying epileptogenesis. A 60 Hz train was applied every 5-10 min to the Schaffer collateral pathways in guinea pig hippocampal slices until epileptiform bursting was elicited in the CA3 region. The resultant alterations in both spontaneous and evoked activities were studied using intracellular recordings from CA3 pyramidal cells. An attempt was made to elucidate the synaptic modifications responsible for the conversion to this state of enhanced excitability. Analyses revealed that the emergence of epileptiform discharge was accompanied by a long-term depression of evoked inhibitory conductances. This tetanus-induced reduction of inhibition involved both the early and late phases of the evoked hyperpolarization, suggesting modification of both the GABAA and GABAB receptor-mediated events. Previous studies have suggested that NMDA receptor activation plays an important role in the induction of epileptiform activity in this model. Our data, showing that depression of inhibition can be induced in the presence of CNQX, is consistent with this hypothesis. The parallel development of long-term depression of inhibition and epileptiform bursting following tetanic stimulation suggests that plasticity of the inhibitory transmission process is a potential source of vulnerability contributing to epileptogenesis.

Acute infectious diarrhea

Diarrhea continues to be a major cause of mortality and morbidity in third world countries as well as a major symptomatic complaint in the primary care setting in the United States. The etiologic pathogen depends on an exposure history to include recent travel to foreign countries, consuming fecally contaminated water or food, prior use of antibiotics, or homosexual behavior. A careful history from patients directed at attempting to identify particular risk factors may help in making a diagnosis. Not all patients require a diagnostic workup. A large number of patients may only require oral rehydration, careful observation over time with or without use of antimotility agents. In toxic appearing patients or patients with fever, however, bloody stools, abdominal pain or tenesmus, a selective diagnostic workup is indicated. Antimicrobial treatments are not always required, some pathogens clearly call for treatment while some have less clear indications and other pathogens are not responsive to antimicrobial agents at all. Finally, one needs to remember that the differential diagnosis of acute diarrhea includes many noninfectious origins.

Pre-reconstruction tattooing eliminates the need for skin grafting in nipple areolar reconstruction

Tattooing the skin of the reconstructed breast as a prelude to reconstruction of the nipple provides a nipple areolar reconstruction that has a uniform color. There is no requirement for a skin graft donor site. Tedious tattooing of the nipple papule is avoided. It is much easier to tattoo a flat surface than a projecting papule, and this technique gives a more uniform color. We believe that this approach to nipple areolar reconstruction provides a simpler, dependable technique.

beta-Carotene inhibits rectal mucosal ornithine decarboxylase activity in colon cancer patients

Colonic adenocarcinoma affects approximately 6% of adults in many Western countries. beta-Carotene (BC), a safe, inexpensive, and widely available compound, has been proposed as a cancer chemopreventive agent. To evaluate whether BC shows promise as an inhibitor of colonic carcinogenesis, we studied 20 male subjects who had previously undergone resection of colonic adenocarcinoma. Each subject received beta-carotene, 30 mg orally, daily for 6 months. Rectal mucosa was sampled at multiple intervals prior to, during, and following BC administration. Mucosal ornithine decarboxylase (ODC) activity and serum and mucosal BC concentrations were determined at each interval. ODC activity was inhibited by 44% (P < 0.05) and 57% (P < 0.01) after 2 and 9 weeks, respectively, of BC administration and remained low compared with baseline even 6 months following discontinuation of BC. Serum and mucosal BC concentrations increased as expected during BC administration and remained elevated for 6 months following BC discontinuation. The demonstrated inhibition of rectal mucosal ODC activity in these patients with resected colon cancer suggests that BC may prove useful as a cancer chemopreventive agent.

Intrinsic properties and evoked responses of guinea pig subicular neurons in vitro

1. Intracellular recordings were used to examine the membrane properties and evoked responses of subicular neurons in horizontal and parasagittal slices from guinea pig brain as a step toward understanding excitatory transmission through the hippocampus. 2. Most cells (49/74) could fire a burst discharge, a portion of which was Ca2+ dependent, in response to direct depolarization or in response to orthodromic or antidromic activation. Other cells (23/74) could not be made to burst, but instead fired single repetitive spikes when directly depolarized or single spikes in response to orthodromic or antidromic activation. Two recorded cells appeared to be interneurons and differed from bursting and non-bursting cells in action-potential shape and response to extracellular stimulation. 3. Bursting cells differed from nonbursting cells in their membrane properties: 1) their time constants were typically shorter (averaging 7.4 ms for bursting cells and 11.5 ms for nonbursting cells), 2) they exhibited a pronounced "sag" in the potential response to hyperpolarizing current injection, and 3) they responded at the break of a hyperpolarizing stimulus with a depolarization (anodal break potential). The sag and the anodal break potential were not detected in recordings from nonbursting neurons. 4. A single-spiking mode could be induced in bursting cells by depolarization from resting potential to about -60 mV. Conversely, hyperpolarization of nonbursting cells did not convert them to bursting cells. 5. Both bursting and nonbursting cell types could be antidromically driven. Whereas both excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) were prominent in nonbursting cells, IPSPs were observed at a lower stimulus intensities than EPSPs in most cells. EPSPs were evident in bursting cells and they triggered burst discharges. IPSPs in bursting cells were detected only when these cells were depolarized, eliminating burst responses. 6. Spontaneous firing rates were low (averaging < 1 spike/s) for both cell types. Addition of picrotoxin produced spontaneous burst or EPSP responses in bursting cells, synchronous with different patterns of picrotoxin-induced population bursts originating in CA3 and/or entorhinal cortex. Individual subicular cells followed CA3 or entorhinal cortex or both. No such activity was recorded in nonbursting cells. No increases in activity in either cell type were seen after picrotoxin application to isolated pieces of subicular cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Graded pneumatic dilation using Rigiflex achalasia dilators in patients with primary esophageal achalasia

Pneumatic dilation is the initial therapy for primary esophageal achalasia. Recently, polyethylene balloon (Rigiflex) dilators have been used with varying success and complication rate. We performed a total of 47 dilations in 29 consecutive patients with achalasia using the Rigiflex dilators. The 3.0-cm balloon was always used first. If there was no symptomatic response, a 3.5-cm balloon was used after 4-8 wk. If there was still no symptomatic response after 4-8 wk, a 4.0-cm dilator was used. Eighteen (62%) patients were successfully dilated with a 3.0-cm balloon only. Of 11 patients not responding to a 3.0-cm balloon, five were dilated successfully with a 3.5-cm balloon. Of six patients not responding to a 3.5-cm balloon, four were successfully dilated with a 4.0-cm balloon dilator. Two patients eventually required surgery. The overall success with Rigiflex balloon dilator was achieved in 27 of 29 (93%) patients. There were no complications. We conclude that pneumatic dilation for esophageal achalasia performed in a graded fashion starting with Rigiflex 3.0-cm balloon dilator has a high success rate without complications in patients with achalasia.

Different firing patterns generated in dendrites and somata of CA1 pyramidal neurones in guinea-pig hippocampus

1. Intracellular recordings, taken from CA1 pyramidal cells in guinea-pig hippocampal slices, were used to examine the origins of repetitive and burst firing in these cells. Single action potentials were elicited by depolarizing current injection at somatic recording sites. In contrast, current injection during intradendritic recordings initiated burst firing in the dendrites. Burst firing could be elicited in the soma by direct depolarization of distal apical dendrites (> 150 microns from the cell body layer) with large extracellular polarizing electrodes. 2. Intracellular recordings were taken simultaneously from the apical dendrites and pyramidal cell somata with the intention of impaling the same neurone with both electrodes. Paired dendrite-soma recordings confirmed that rhythmic single action potentials were generated at the cell soma, whereas bursts of action potentials were initiated in the distal apical dendrites (> 150 microns from the cell body layer). Fast spikes in the dendrite often triggered fast spikes in the soma, but not all fast spikes in the dendritic burst were 'relayed' to the soma. 3. In paired recordings, when a dendritic action potential failed to elicit a full somatic action potential, a 'd-spike' was commonly recorded in the soma. Somatic d-spikes were uniform all-or-none responses that could be shown, in some cases, to trigger the full somatic action potentials. 4. Attenuated spikes could be recorded in the dendrites, triggered by action potentials initiated at the cell soma. Dendritic responses to somatic stimulation sometimes varied in amplitude, but always showed a direct correspondence with somatic action potentials. 5. Dendritic recordings taken closer to the pyramidal cell bodies (< 150 microns from the cell body layer) showed a 'transitional' region where single action potentials rather than burst discharges could be evoked. After-potentials of these single spikes differed from those associated with somatic spikes in that proximal dendritic spikes had depolarizing after-potentials. The observed shift from after-hyperpolarization to depolarizing after-potentials in intradendritic recordings taken progressively further from the cell body corresponds to the change from repetitive to burst firing. 6. The results indicate that activity of the CA1 pyramidal cell soma, presumably a reflection of its output, can be either burst or repetitive firing. Somatic 'bursts,' unlike the burst discharges seen in the apical dendrites or the burst discharges reported in CA3 cells, are not initiated locally. Rather, they appear to be simply a rapid spike-for-spike response by the soma to the fast spikes that form part of the apical dendritic burst.(ABSTRACT TRUNCATED AT 400 WORDS)

Aeromonas hydrophila infections following use of medicinal leeches in replantation and flap surgery

Aeromonas hydrophila infections are a recognized complication of postoperative leech application, and can occur with measurable frequency in populations of patients treated with leeches. We review 11 previously reported leech-related Aeromonas infections and analyze seven unreported cases. These infections range from minor wound complications to extensive tissue loss and sepsis. Often, these infections followed leech application to tissue with questionable arterial perfusion. Onset of clinical infection in these patients ranged from within 24 hours of leech application to 10 days or more after leech application. Late infections may represent bacterial invasion from colonized necrotic tissue. Based on these observations, we recommend that leech applications be restricted to tissue with arterial perfusion to minimize contamination of necrotic tissue. We also recommend that patients treated with leeches receive antibiotics effective against Aeromonas hydrophila before leech application. Patients treated with leeches and discharged with eschars or open wounds might benefit from oral antibiotic therapy until wound closure. These precautions may minimize or eliminate this complication of leech use.

Different effects of intracellular and extracellular TEA on voltage-dependent K currents of acutely isolated hippocampal CA1 neurons

Tetraethylammonium (TEA) effects on K currents were examined on either side of the membrane of hippocampal CA1 neurons by means of whole-cell voltage-clamp recording and intracellular perfusion. Recording media contained ion channel blockers to allow the selective activation of voltage-dependent K currents which consisted of a rapidly decaying component (A-current) and a delayed component. Voltage protocols were applied to separate the A-current from the delayed component. Results show that 10 mM extracellular TEA suppressed 50 +/- 11% (S.D., n = 4) of the delayed current at different levels of depolarization but had little effect on the A-current. In contrast 10 mM TEA applied by intracellular perfusion suppressed the A-current by 42 +/- 10% (S.D., n = 4) in addition to inhibiting the delayed currently 55 +/- 15% (S.D., n = 4). Both the intracellular and extracellular actions of TEA on K currents showed no voltage- nor time-dependency. The results suggest that voltage-dependent transient current (A-current) is mediated through a separate group of ionic channels distinct from those that sustained the delayed current. Furthermore, the asymmetrical effects of intracellular and extracellular TEA on the transient current are similar to those described for the A-current in molluscan neurons. This observation supports the notion that the structure of the ion channel mediating the A-current is closely conserved across different species.

Serum and tissue zinc concentrations in patients with endoscopic esophagitis

Because zinc is an important metabolic requirement for growth and repair of squamous tissue, we questioned whether changes in serum and esophageal tissue zinc were present in patients with reflux esophagitis. To investigate this question, we prospectively studied 49 patients undergoing upper gastrointestinal endoscopy for symptoms of abdominal pain and discomfort; 19 patients were taking H2 antagonists at the time of the study. Blood was obtained to measure serum zinc concentrations prior to endoscopy and tissue zinc levels were obtained from esophageal biopsies from the distal, middle, and proximal esophagus in patients who were either endoscopically normal or who exhibited endoscopic esophagitis. Serum zinc concentrations were significantly lower in patients with endoscopic esophagitis compared to the endoscopically normal group (77 +/- 3.8 micrograms/dl vs 88 +/- 2.4 micrograms/dl, P less than 0.02). Distal esophageal tissue concentrations were significantly higher in patients with endoscopic esophagitis compared to the endoscopically normal group (200 +/- 30 micrograms/liter vs 135 +/- 15 micrograms/liter, P less than 0.05); whereas there were no differences between values obtained in the proximal or middle esophagus. Serum and tissue zinc concentrations in patients with esophagitis receiving H2 antagonists were more similar to values obtained in patients who were endoscopically normal than to patients with endoscopic esophagitis without treatment. This study suggests that in endoscopic esophagitis: (1) greater amounts of zinc are concentrated in the rapidly proliferating distal esophageal epithelium, (2) the serum zinc pool may serve as a major zinc source, and (3) decreasing esophageal mucosal inflammation with H2 antagonists may decrease zinc loss via the esophageal epithelium.