Biomedical subjects

J M Velasco

Publications and source records attributed to J M Velasco.

33 records · Page 2Linked to original sources

PubMed1993

Laparoscopic versus conventional appendectomy.

OBJECTIVE: The goal of this study was to prospectively define the impact of laparoscopy on the management of patients with a presumed diagnosis of appendicitis. SUMMARY BACKGROUND DATA: While the role of laparoscopy in the management of cholelithiasis is well established, its impact on the management of acute appendicitis needs to be objectively defined and compared to that of conventional management. Several authors have predicted that laparoscopic appendectomy will become the preferred treatment for appendicitis. METHODS: Two groups of consecutive patients with similar clinical characteristics of acute appendicitis were compared. Data on the laparoscopic group were compiled prospectively on standardized forms; data on the conventional group were collected retrospectively. Operative time, hospital stay, analgesia, cost, and return to normal activities were noted. RESULTS: Seventeen consecutive patients who underwent appendectomy were compared to 18 consecutive patients who underwent laparoscopy (16 of these 18 had laparoscopic appendectomy). There was no significant difference between the two groups in terms of clinical characteristics and appendiceal histopathology. The mean operative times were 61 +/- 4.1 minutes and 46 +/- 2.9 minutes for the laparoscopy and conventional groups, respectively (p < 0.01). Hospital stay was significantly shorter in the laparoscopic appendectomy group, with 81% of patients being discharged on their first postoperative day (p < 0.001). The laparoscopic appendectomy patients required significantly less narcotic analgesia (p < 0.02). Return to normal activity was not significantly different between the two groups. The average total cost of laparoscopic appendectomy was 30% greater than that of conventional appendectomy. CONCLUSIONS: Laparoscopy is a useful adjunct to the management of patients with a presumed clinical diagnosis of acute appendicitis.

Acute Disease↗

PubMed1989

Suprarhinal cortex response to electrical stimulation of the lateral amygdala nucleus in the rat.

Electrical stimulation of the lateral amygdala nucleus was found to evoke field potentials and influence unitary activity in the suprarhinal cortex of anesthetized rats. Laminar distributions of the field responses consisted of positive waves in superficial layers, that reversed to electronegatives from a depth of 0.4-0.5 mm. This response was followed by a shallow electropositive wave deeper than 0.7-0.8 mm. Extracellularly recorded units were studied in the posterior agranular insular area of the suprarhinal cortex. The data revealed that stimulation of the lateral amygdala produced a train of small amplitude spikes in association with a negative slow potential. Furthermore, such stimulation invariably elicited an inhibition of the spontaneous firing of large amplitude spikes, in association with a positive slow potential. The onset of this inhibitory response always occurred at longer latency than the excitatory one. The small amplitude spikes may well represent the firing of inhibitory interneurons after lateral amygdala stimulation. The study suggests that a feed-forward system of inhibition appears to be present in the connection between lateral amygdala and posterior agranular insular area of the suprarhinal cortex.

Amygdala↗

PubMed1989

The effect of a cell-permeable diacylglycerol analogue on single Ca2+ (Ba2+) channel currents in the insulin-secreting cell line RINm5F.

Depolarization evokes opening of single Ca2+ (Ba2+) channels of the 'L' type in the insulin-secreting cell line RINm5F. Stimulation of the cells with the membrane-permeable diacylglycerol analogue didecanoylglycerol (DC10; 5 micrograms/ml) markedly enhanced the proportion of time the channels spent in the open state during depolarizing voltage pulses. Similar effects have previously been demonstrated with glyceraldehyde stimulation and it therefore seems possible that carbohydrate-evoked cellular Ca2+ uptake is mediated via protein kinase C activation.

Calcium Channels↗

PubMed1988

Single-channel Ba2+ currents in insulin-secreting cells are activated by glyceraldehyde stimulation.

Single-channel Ba2+ current recordings have been made from the insulin-secreting cell line RINm5F with the patch-clamp technique. Depolarization evokes opening of Ca2+ (Ba2+) channels with a relatively high conductance (30 pS) and during the 200 ms depolarizing pulses there is no inactivation. The threshold is high as 50 mV depolarization from the resting membrane potential of -70 mV is required for any channel opening to occur. Glyceraldehyde, a substance evoking insulin secretion from the RINm5F cells, enhances the voltage-activated Ca2+ channel opening by increasing the mean open time and decreasing the longer of the two mean shut times and also decreases the voltage threshold for channel opening.

Action Potentials↗

PubMed1988

Unitary activity in the suprarhinal cortex of the rat and its modulation after lateral amygdala stimulation.

Unitary responses in the suprarhinal cortex were studied in anesthetized rats. Lateral amygdala stimulation gave rise to two types of cortical responses: (i) an excitatory response (59%) characterized either by a single spike discharge, or by a burst of two to four spikes, or (ii) an inhibitory response (41%) affecting cortical neurons which exhibited spontaneous discharge. The duration of inhibition appeared to be related to the intensity of stimulation and the spontaneous discharge frequency.

Amygdala↗

PubMed1987

Medialis dorsalis thalamic unitary response to tooth pulp stimulation and its conditioning by brainstem and limbic activation.

In nembutalized cats tooth pulp stimulation (TPS) was effective in exciting 18% of medialis dorsalis (MD) thalamic units. Facilitation of spontaneous MD unitary discharge followed high frequency stimulation of the lateral amygdala (25%), dorsal hippocampus (22%), mesencephalic reticular formation (20%) and septal nuclei (17%). Conditioning high-frequency stimulation of limbic and reticular structures, strongly facilitated the MD unitary responses to TPS. None of the thalamic neurons involved in nociception seems to project to the cerebral cortex. The conditioning effect on MD response of limbic and reticular stimulation suggests that these central structures may be involved in the modulation of the nociceptive input.

Animals↗

PubMed1987

Voltage-activation of high-conductance K+ channel in the insulin-secreting cell line RINm5F is dependent on local extracellular Ca2+ concentration.

Patch-clamp single-channel current recording experiments have been carried out on intact insulin-secreting RINm5F cells. Voltage-activation of high-conductance K+ channels were studied by selectively depolarizing the electrically isolated patch membrane under conditions with normal Ca2+ concentration in the bath solution but with or without Ca2+ in the patch pipette solution. When Ca2+ was present in the pipette, 40 mV to 120 mV depolarizing pulses (100 ms) from the normal resting potential (-70 mV) regularly evoked tetraethylammonium-sensitive large outward single-channel currents and the average open state probability during the pulses varied from about 0.015 (40 mV pulses) to 0.1 (120 mV pulses). In the absence of Ca2+ in the pipette solution the same protocol resulted in fewer and shorter K+ channel openings and the open-state probability varied from about 0.0015 (40 mV pulses) to about 0.03 (120 mV pulses). It is concluded that Ca2+ entering voltage-gated channels raises [Ca2+]i locally and thereby markedly enhances the open-state probability of tetraethylammonium-sensitive voltage-gated high-conductance K+ channels.

Calcium↗

PubMed1982

Detection of pancreatic tumors by ultrasound during surgery.

Real-time B-mode ultrasonic scanning was performed during 14 operations for pancreatic tumors. All operations were for adenocarcinoma, except in one patient with a Zollinger-Ellison tumor. The ultrasonic tissue appearance of pancreatic carcinoma was not specific. However, ultrasonic signs of pancreatic duct dilation, striction or invasion of the superior mesenteric veins, and common bile duct involvement may help to establish the diagnosis of malignancy. A triad of ultrasound signs indicative of malignant obstruction of the common bile duct consisted of (1) dilation, (2) absence of biliary stones, and (3) a distinctive termination pattern of the duct. Operative ultrasound was used to guide a biopsy needle to obtain pancreatic tissue samples. The Zollinger-Ellison tumor of the pancreas produced a sonolucent appearance that clearly distinguished it from the surrounding tissue.

Adenocarcinoma↗

PubMed1982