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Biomedical subjects

J M Velasco

Publications and source records attributed to J M Velasco.

At least 19 recordsLinked to original sources
PubMed1998

A prospective analysis of office-based breast ultrasound.

OBJECTIVE: To determine the usefulness of office-based breast ultrasound. DESIGN: Prospective, nonrandomized study. SETTING: Academic-affiliated community teaching hospital. PATIENTS: Among 653 consecutive patients seen in our office during a 30-month period, we performed 660 ultrasound examinations. The presenting complaint included a palpable mass in 53%, abnormal mammogram in 39%, and nipple discharge or retraction in 3%. INTERVENTION: Ultrasound examination was performed using a handheld 7.5-MHz linear array transducer. Findings and pertinent clinicopathologic data were recorded prospectively in our Breast Ultrasound Registry. MAIN OUTCOME MEASURE: Contribution of breast ultrasound to diagnosis and treatment. RESULTS: The sonogram was normal in 201 cases (30%), showed duct ectasia in 20 cases (3%), a simple cyst or seroma in 101 cases (15%), and a focal complex or solid abnormality in 338 cases (51%). Among the last group, 114 (97%) of 118 lesions thought to be benign on ultrasonography proved to be benign, whereas 13 (12%) of 111 indeterminate and 72 (75%) of 96 sonographically suspicious lesions proved to be cancer (including 13 cases with normal mammograms). Ultrasonographic features of malignancy included an anteroposterior-to-lateral dimension ratio of 1 or greater, heterogeneous hypoechoicity, irregular shadowing, and fuzzy and/or jagged margins. Ultrasound-guided needle biopsy accurately diagnosed 46 benign nonpalpable lesions and 20 malignant nonpalpable lesions. CONCLUSIONS: These data suggest that ultrasonography is a useful adjunct to clinical and mammographic evaluation of breast disease. Breast ultrasound identifies cysts, aids in differentiating benign from malignant lesions, and facilitates office needle biopsy of nonpalpable abnormalities, permitting timely and cost-effective patient care.

Adolescent↗
PubMed1998

Postlaparoscopic small bowel obstruction. Rethinking its management.

BACKGROUND: Patients with early postoperative small bowel obstruction (SBO) are usually managed nonoperatively with nasogastric suction, intravenous fluids, and observation. The majority of early postoperative SBO resolve without an operation. METHODS: We performed a retrospective review of patients who had been diagnosed with postlaparoscopic SBO at three Chicago area teaching hospitals. RESULTS: The patients were initially managed nonoperatively for up to 7 days. However, all of them subsequently required an operation. In every case, the postlaparoscopic SBO was caused by the small bowel being incarcerated in a peritoneal defect created either by trocar placement or peritoneal incision for herniorrhaphy. CONCLUSION: In contradistinction to the approach used for early SBO after laparotomy, prompt operative intervention for postlaparoscopic SBO is recommended.

Adult↗
PubMed1998

Laparoscopic herniorrhaphy in the geriatric population.

Laparoscopy has brought controversy to herniorrhaphy, particularly in the elderly. We reviewed our experience with this technique in patients older than 65 years at a single teaching institution. Data include demographics, American Society of Anesthesiologists (ASA) class, operative time, hernia type, type of repair, hospital stay, and complications. A telephone questionnaire was used to assess return to normal activity, recurrence, and reason for choosing the laparoscopic approach. From March 1992 through March 1996, 110 of 328 patients were eligible. Mean age was 73 +/- 5.6 years; 34 patients had bilateral and 20 had recurrent hernias; 73 patients (66.4%) were ASA-2, and 22 (20%) were ASA-3. The extra-abdominal and transabdominal preperitoneal approaches were used in 64 and 46 patients, respectively; mean operative time was 87.9 +/- 34 minutes. The overall complication rate was 15 per cent, with 71 per cent of these being urinary retention. Patients were discharged the same day (59%) and at 1 day (33%). Follow-up was available in 84.5 per cent. Recurrence rate was 9.7 per cent, which was not significantly influenced by complication rate, hernia repair type, or ASA class. Median return to normal activity was 7 days. ASA classification correlated with hospital stay (P = .02), but not with complications, recurrence, or return to normal activities (P = not significant). Laparoscopic herniorrhaphy appears safe in the elderly.

Aged↗
PubMed1998

Use of ultrasound-guided fine needle aspiration biopsy in the management of thyroid disease.

Fine-needle aspiration biopsy (FNAB) of thyroid nodules has resulted in fewer patients needing thyroidectomy. Nondiagnostic FNAB specimens may require surgery for diagnosis. Ultrasound can help decrease nondiagnostic biopsies by visualizing lesions and guiding biopsy needles. Between 1996 and 1997, 76 patients had ultrasound-guided needle biopsies of thyroid nodules. Sixteen patients had clearly palpable nodules, whereas 19 were described as difficult to palpate. There were 32 patients who presented with either prominent thyroids or enlarged lobes. Six patients presented only with nonspecific symptoms, and 3 had nodules discovered incidentally on imaging studies. Biopsies were diagnostic in 73 of 76 (96%) patients. This varied with the size of the nodule, with the rate of nondiagnostic biopsies being 13 per cent in lesions <1.0 cm and 3 per cent in lesions >2.0 cm. Fifteen patients had surgery based on the FNAB, with a surgical yield of malignancy of 47 per cent. Ultrasound-guided FNAB is extremely useful in evaluating thyroid lesions that are difficult to palpate or nonpalpable, as well as the remainder of the gland and surrounding structures. The use of ultrasound guidance in performing FNAB results in a low rate of nondiagnostic biopsies, which may decrease the number of unnecessary thyroidectomies performed to rule out malignancy.

Biopsy, Needle↗
PubMed1997

Different voltage-gated sodium currents are expressed by human neuroblastoma NB69 cells when cultured in defined serum-free and in astroglial-conditioned media.

Voltage-gated Na+ currents (INa) were analysed with the whole-cell patch-clamp technique in human neuroblastoma NB69 cells plated in serum-free "defined" medium (DM) or in "astroglial-conditioned" medium (CM). Cells survived in both media and expressed the microtubule associated protein 1A, indicating neuron-like differentiation. Two INa types with different time-, voltage-dependent properties and tetrodotoxin (TTX) sensitivities were expressed in DM and CM. The INa in DM-plated cells was present from day 4 and its surface density increased from 11 pA/pF (days 5-7) to 68 pA/pF (days 15-30). The underlying conductance (GNa) half-activated (V0A) at -24 mV. INa inactivation was fitted by single exponentials with 7.5 ms time constant (th) at the -35 mV half-inactivation voltage (V0I). INa was not affected by 10 nM, was reduced (65%) by 100 nM, and not completely abolished (92%) by 300 nM tetrodotoxin (TTX). The INa of CM-plated cells appeared at day 3-4 and its surface density increased from 14 pA/pF (days 3-6) to 28 pA/pF (days 11-14). The GNa V0A was -29 mV and inactivation was fitted by single exponentials with 2.6 ms that the -58 mV V0I. This INa was reduced (55%) by 10 nM and totally abolished by 100 nM tetrodotoxin (TTX). In conclusion, NB69 cells displayed a slow, "TTX-resistant," or a fast, "TTX-sensitive" INa in DM and CM, respectively, suggesting that the CM contained diffusible trophic factors of astroglial origin that induced the expression of a different Na+ channel type. About half of the CM- and DM-plated cells also displayed a persistent Na+ current (INaP).

Action Potentials↗
PubMed1997

Differential expression of voltage-gated Ca2+ conductances in human neuroblastoma NB69 cells cultured in defined serum-free and astrocyte-conditioned media.

Voltage-gated Ca2+ conductances were investigated with the whole-cell patch-clamp technique-either using Ca2+ or Ba2+ as charge carriers-in NB69 human neuroblastoma cells plated in "defined" serum-free (DM) and in "astroglial-conditioned" media (CM). Cells expressed the microtubule associated protein 1A when plated in both media, indicating neuronlike differentiation. Cells of similar sizes and shapes were selected for recordings. Different sets of voltage-gated Ca2+ current types were usually expressed in DM- and CM-plated cells. DM-plated cells exhibited a high-voltage-activated current (HVAC) in isolation, whereas 43% of the CM-plated cells also displayed the low-voltage-activated current (LVAC). The membrane surface density of the HVAC was about twofold higher in CM than in DM-plated cells and increased with plating time from 10 and 16pA/pF (days 1-4) to 24 and 37 pA/pF (days 5-10) in DM- and CM-plated cells, respectively. However, the amplitude of the LVAC did not change significantly with culture age. In conclusion, NB69 cells expressed HVAC in isolation when plated in DM, whereas both HVAC and LVAC were present in many CM-plated cells, suggesting that the CM contained diffusible factors secreted by astroglial cells which: (1) could induce the appearance of the LVAC and (2) increased HVAC current expression.

Astrocytes↗
PubMed1996

The influence of laparoscopy on lymphocyte subpopulations in the surgical patient.

BACKGROUND: Surgical stress is known to disturb the immune system so that the overall picture is one of generalized immunosuppression proportional to the degree of stress. It has been suggested that minimally invasive procedures, i.e., laparoscopic cholecystectomy, should be accompanied by decreased surgical stress. METHODS: The present study utilized a panel of monoclonal antibodies to identify peripheral blood lymphocyte subpopulations in 11 patients scheduled for elective laparoscopic cholecystectomy. These were obtained immediately preoperatively, one day postoperatively, and one week postoperatively. RESULTS: The results demonstrated a significant (p < 0.05) decrease in T-helper to T-suppressor cell ratios the first day postoperatively compared to the preoperative ratios; the mean decrease was 13% below the preoperative ratios. There was no significant change in the ratios one week postoperatively. CONCLUSIONS: Even though laparoscopic cholecystectomy has been documented to have less disability and postoperative pain than open cholecystectomy, alterations in immune function, although attenuated, do persist.

Adult↗
PubMed1996

Preperitoneal bilateral inguinal herniorrhaphy evolution of a technique from conventional to laparoscopic.

BACKGROUND: Simultaneous repair of bilateral inguinal hernia remains controversial. METHODS: Seventy-two consecutive patients underwent a preperitoneal prosthetic repair of bilateral groin hernia; 25 via laparoscopy. ASA classification, Nyhus type, hospitalization, convalescence time, and cost were examined. Mean follow-up was 36 and 12 months for the conventional and laparoscopic group respectively. RESULTS: Sixty-nine patients were available for long-term follow-up. Average hospital stay, recurrence rate, perioperative urinary retention, transient thigh neuralgia, and return to normal activities were 48 hours, 5%, 9%, 6%, and 22 days as compared to 4 hours, 6%, 20%, 12%, and 9 days for the conventional and laparoscopic group respectively. The cost for laparoscopic repair was $500 greater. CONCLUSIONS: The preperitoneal approach to repair of bilateral hernias demonstrates an acceptable recurrence rate with low long-term morbidity. Experience with conventional preperitoneal technique greatly facilitates transition to laparoscopic repair.

Costs and Cost Analysis↗
PubMed1994

A technique for laparoscopic retraction of the acutely inflamed thick-walled gallbladder.

Utilizing the described technique, we have been able to obtain adequate cephalad retraction of the acutely inflamed, tense, and thick-walled gallbladder with minimal trauma. This has made it possible to more adequately identify key anatomical landmarks and to more safely perform the dissection in this area. We believe that the benefits of a shorter hospital stay, decreased postoperative pain, and earlier return to normal activity that patients realize when having an elective laparoscopic cholecystectomy for chronic cholecystitis can be made available as well to more patients presenting with acute cholecystitis.

Acute Disease↗
PubMed1994

Laparoscopic cholecystectomy in acute cholecystitis.

Between January 1991 and December 1992, 220 patients underwent laparoscopic cholecystectomy and were monitored prospectively. Twenty-seven patients (12.3%) had acute cholecystitis, according to strict clinical and pathologic criteria. Their average age was 60.4 years. The average operative time was 121 min. Two of the 27 patients (7.4%) required conversion to open laparotomy. The postoperative morbidity rate was 11%. The average hospital stay was 1.9 days. This series provides further evidence that laparoscopic cholecystectomy can be used safely and effectively to treat acute cholecystitis when performed by experienced surgeons.

Acute Disease↗
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↗