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Biomedical subjects

D F Jimenez

Publications and source records attributed to D F Jimenez.

At least 19 recordsLinked to original sources
PubMed2006

Canine intraneural perineurioma.

A 6-year-old castrated German Shepherd Dog was presented with a 6-month history of progressive, nonpainful, left pelvic limb paresis. Magnetic resonance imaging revealed atrophy of left-sided epaxial and hypaxial muscles from L5-L7 and an enlarged L5 spinal nerve. Exploratory hemi-laminectomy revealed focally and cylindrically thickened L5 and L6 nerve roots. Histologic evaluation of a surgical biopsy specimen from the L6 dorsal nerve root, and the L5 nerve roots after later amputation revealed distended hypercellular fascicles. This distension was due to widely separated axons surrounded by concentric lamellations formed by neoplastic perineurial cells and their processes. These pseudo-onion bulbs were separated from each other by a basophilic myxoid stroma. The perineurioma cell processes were immunonegative for S-100 (alpha and beta chains) and collagen IV, but were immunoreactive for laminin. The central axons were also immunoreactive for NF-200 and S-100. The proliferative index of the perineurioma cells, as determined by MIB-1 immunoreactivity, was about 3%. Ultrastructurally, the widely separated, interdigitating perineurioma cell processes were connected by desmosomal-like junctional complexes to form continuous circles. Their processes were covered by a discontinuous basal lamina. Each centrally placed axon was normally, thinly, or completely unmyelinated and was surrounded by a normal Schwann cell. These morphologic and immunologic features distinguish this lesion from hypertrophic neuropathy and were consistent with intraneural perineurioma.

Animals↗
PubMed2005

HIV-1-derived lentiviral vectors and fetal route of administration on transgene biodistribution and expression in rhesus monkeys.

The gene transfer efficiency of lentiviral vectors pseudotyped with vesicular stomatitis virus-glycoprotein (VSV-G) driven by the MND or CMV promoters and expressing the enhanced green fluorescent protein (EGFP) was investigated in fetal rhesus monkeys (Macaca mulatta) (N=21). Fetuses (50+/-10 days gestation; term 165+/-10 days) were injected under ultrasound guidance using an intraperitoneal (i.p.) or intrahepatic (i.h.) approach with a range of 1 x 10(7)-2 x 10(8) infectious particles/fetus. Analysis of transgene biodistribution and expression was performed in multiple tissues at 3-7 months postgene delivery using quantitative techniques. Overall, results indicated the following: (1) i.p. gene transfer at 40 days gestation resulted in a more diffuse distribution of the vector compared to administration at 60 days gestation; (2) vector biodistribution was similar after administration by the i.p. or i.h. routes; and (3) gene expression analysis in transduced tissues showed the presence of mRNA transcripts that correlated with the level of gene transfer. These studies suggest that fetal gene transfer using the i.p. and i.h. routes results in prolonged transduction and expression of the transgene in multiple tissues.

Animals↗
PubMed2001

Venous air embolism during endoscopic strip craniectomy for repair of craniosynostosis in infants.

BACKGROUND: Various studies have reported an incidence of venous air embolism (VAE) as high as 82.6% during surgical procedures for craniosynostosis. There has been an increase in the use of minimally invasive, endoseopie surgical procedures, including applications for endoscopic strip craniectomy. The current study prospectively evaluated the incidence of VAF during endoscopic strip craniectomy. METHODS: Continuous, intraoperative monitoring for VAE was performed using precordial Doppler monitoring. A recording was made of the Doppler tones and later reviewed to verify its accuracy. RESULTS: The cohort for the study included 50 consecutive neonates and infants ranging in age from 3.5 to 36 weeks and ranging in weight from 3 to 9 kg. Surgical time varied from 31 to 95 min for a total of 2,701 mm of operating time, during which precordial Doppler tones were auscultated. In 46 patients, there was no evidence of VAE. In four patients, there was a single episode of VAE. Two of the episodes of VAE were grade I (change in Doppler tones), and two were grade H (change in Doppler tones and decrease in end-tidal carbon dioxide). No grade III (decrease in systolic blood pressure by 20% from baseline) VAF was noted. CONCLUSION: In addition to previously reported benefits of decreased blood loss, decreased surgical time, and improved postoperative recovery time, the authors noted a low incidence of VAF during endoscopic strip craniectomy in neonates and infants.

Craniosynostoses↗
PubMed2001

Effects of synthetic craniofacial materials on cerebral microcirculation.

Four groups were studied to look at effects of synthetic materials on the pial vasculature. Using Sprague-Dawley rats, an open pial window approach was used in which there was a control group, a hydroxyapatite cement group mixed with sodium phosphate, a methylmethacrylate slow-set, and a methylmethacrylate fast-set group. There were 10 animals with 20 vessels studied within each group. The permeability leakage outside the vessel was evaluated to determine the vascular albumin leakage, and the number of rolling and adherent leukocytes was studied within each group. It was seen that the control group was significantly different compared with the fast-set methylmethacrylate group during a 2-hour period in regard to the percentage leakage, as well as a number of rolling and adherent leukocytes. This is one of the first studies to demonstrate the effects of synthetic craniofacial materials on the underlying pial vasculature.

Animals↗
PubMed2001

Temporalis muscle resuspension using titanium miniplates and screws: technical note.

OBJECTIVE: To describe the technique for and results of using titanium miniplates and screws for resuspension of the temporalis muscle after osseous detachment during cranial procedures requiring exposure of and access to the frontotemporoparietal region. METHODS: Thirty-four patients, who were being treated with various cranial procedures, underwent resuspension of the dissected temporalis muscle, using 1.5-mm or 1.3-mm titanium plates and screws, after bone flap replacement. RESULTS: The temporalis muscle was successfully and securely resuspended in all cases, using the plates and screws. There were no infections, muscle tears, dislodgement, fractures, or temporal hollowing in any of the cases. In four cases that required re-exploration, the muscle was observed to be rigidly fixated and scarred to the bone. CONCLUSION: The use of titanium plates and screws is a safe, simple, successful alternative for reattachment of temporalis muscles for patients undergoing cranial procedures.

Adolescent↗
PubMed2001

Primary canine and feline nervous system tumors: intraoperative diagnosis using the smear technique.

The recent application of neuroimaging techniques in veterinary neurology has led to the accurate localization of many types of intracranial lesions but has also created a clinical need, particularly with brain tumors, for a specific intraoperative diagnosis. For human brain tumors, a smear technique has been used successfully for many years to provide an extremely rapid, highly accurate intraoperative diagnosis. In similar smear preparations of intracranial lesions, obtained either by computed tomography (CT)-guided stereobiopsy or from a craniotomy, we have described distinguishing cytologic features of some primary spontaneous nervous system tumors in 80 dogs and 13 cats. A final diagnosis was confirmed by evaluation of paraffin-embedded sections from the same sample and, when appropriate, by immunocytochemical staining. Preliminary findings indicate that, in dogs and cats, this procedure is useful for rapid, accurate intraoperative diagnosis of many primary nervous system tumors. The distinguishing features of the canine and feline tumors bear a remarkably close resemblance to their human counterparts.

Animals↗
PubMed2000

Endoscopy-assisted wide-vertex craniectomy, "barrel-stave" osteotomies, and postoperative helmet molding therapy in the early management of sagittal suture craniosynostosis.

OBJECT: The purpose of this study was to assess the efficacy, safety, associated complications, and outcome in patients with sagittal suture craniosynostosis in whom endoscopy-assisted wide-vertex craniotomy and "barrel-stave" osteotomy were performed. METHODS: During a 4-year period, 59 patients with sagittal suture synostosis underwent endoscopy-assisted wide-vertex craniectomies, barrel stave-like osteotomies, and postoperatively were fitted with custom-made molding helmets. Data on operative time, blood loss, transfusion rates, hospital length of stay, complications, and hospital charges were collected prospectively. The mean patient age at the time of surgery was 3.7 months. The average blood loss was 31.8 ml; and only one patient required an intraoperative blood transfusion. Nine patients received transfusions of donor blood postoperatively. The mean operative time was 50 minutes, and all but three patients were discharged from the hospital the morning following surgery. There were no intraoperative complications. Normocephaly as well as normal cephalic indices were observed at latest follow up. CONCLUSIONS: The authors conclude that early treatment of infants with sagittal suture craniosynostosis by using minimally invasive, endoscopy-assisted wide-vertex craniectomies provides excellent results and a significantly lower morbidity rate than traditional calvarial vault reconstructive procedures.

Blood Transfusion↗
PubMed2000

BoneSource solidification: a comparison between water and sodium phosphate as the solvent.

The purpose of this study was to determine the solidification rates for BoneSource (hydroxyapatite cement) mixed with sterile water versus BoneSource mixed with 0.25 ml of sodium phosphate. The average time for cure for BoneSource mixed with sterile water was 99 minutes, with a SD of 5.3 minutes. The average time for cure for BoneSource and sodium phosphate was 43 minutes, with a SD of 3.6 minutes (P < 0.0003). The average temperature for BoneSource in sterile water was 19.1 degrees C with a SD of 0.082, and the average temperature of BoneSource in sodium phosphate was 20.1 degrees C, with a SD of 0.1. Therefore, sodium phosphate shows that there is a significantly decreased amount of time required to solidify BoneSource and it remains isothermic throughout this reaction.

Bone Cements↗
PubMed1999

Endoscopic craniectomy for early correction of craniosynostosis.

Twelve patients between 0.4 and 7.8 months of age were treated by an endoscopic approach to strip craniectomy. Nine patients had sagittal suture involvement. Two patients had a single unilateral lambdoid suture synostosis, and one patient had a combination of a right coronal synostosis and a metopic synostosis. Postoperatively, all patients were placed in cranial remodeling helmets and the results showed that the estimated blood loss ranged from 5 cc to 150 cc, with blood transfusion required in only one patient. All patients were discharged from the hospital by day 2, and all patients had an improvement in their cranial head shape. The specific technique of using the endoscope to aid in performing a strip craniectomy will be discussed. Nine endoscopically treated patients with the diagnosis of sagittal suture synostosis were compared with nine patients treated by using the Marchac remodeling techniques. The mean operative time (1.6 hours versus 3.5 hours), estimated blood loss (43 cc versus 168 cc), hospital costs ($11,671 versus $36,685), and length of stay (1.16 days versus 5.1 days) were less by using the endoscopic technique. All nine patients treated by using the Marchac technique required a blood transfusion, whereas only one patient was transfused in the endoscopically treated group.

Brain↗
PubMed1999

Propofol for sedation and control of intracranial pressure in children.

Following central nervous system insults, control of intracranial pressure may lessen the incidence of morbidity and mortality. Therapies to control intracranial pressure include osmolar agents, prevention of and control of seizures, drainage of cerebrospinal fluid, hypothermia, and barbiturates. Control of agitation and excessive patient movement are additional components in the management of ICP. Although opioids and benzodiazepines are generally effective, in a small subset of patients, alternative agents may be necessary. The authors present 2 children with increased ICP in whom propofol was used to provide sedation and control ICP. The use of propofol in this setting and its possible applications in the children with increased ICP are discussed.

Child↗
PubMed1998

Socioeconomic issues and education of neurologic surgery residents in the United States.

BACKGROUND: The goals of this project were to ascertain the extent to which socioeconomic issues are being formally addressed within neurologic training programs in the United States and to determine the perception of chief neurosurgery residents and program directors regarding training and preparation as it relates to these issues. METHODS: The chief neurosurgery residents and program directors for the 1995 academic year were identified and mailed a survey with questions regarding the formal training of socioeconomic issues within their programs. RESULTS: Residents indicated that 95% did not believe their residency program provided adequate training in socioeconomic issues; 97% and 95% respectively, did not feel adequately prepared to deal with the business aspects of a medical practice or to deal with insurance companies and the managed care environment; and 87% did not think they were adequately prepared to deal with a lawsuit. Moreover, from 25%-87% did not know the meaning of terms such as capitation, RVUs, PPOs, or IPAs. The program directors indicated that 58% of the programs did not formally deal with socioeconomic issues. CONCLUSIONS: This survey indicates that socioeconomic issues are not currently being properly addressed in a large proportion of neurosurgical residency programs. An overwhelming majority of the residents did not feel they are adequately prepared to deal with those nonmedical-surgical aspects of the practice of neurosurgery. This perception was corroborated by the response of the program directors. There appears to be a significant deficiency in the training of neurosurgical residents with regard to socioeconomic issues in the United States.

Education, Medical↗
PubMed1998

Endoscopic craniectomy for early surgical correction of sagittal craniosynostosis.

OBJECT: The authors sought to minimize scalp incisions, blood loss, and operative time by using endoscopically assisted strip craniectomies and barrel-stave osteotomies to treat infants with sagittal suture synostosis. METHODS: Four patients, aged 2, 4, 9, and 12 weeks, who presented with scaphocephaly underwent endoscopic midline craniectomies through small midline scalp incisions. The mean operative time for the procedure was 1.68 hours (range 1.15-2.8 hours); the mean blood loss was 54.2 ml (range 12-150 ml). Three patients did not require blood transfusions and were discharged within 24 hours. Postoperatively, all patients were fitted with custom cranial molding helmets. Follow-up evaluation ranged between 8 and 15 months. All patients had successful correction of their scaphocephaly with no mortalities, morbidities, or complications. CONCLUSIONS: The use of endoscopic techniques for early correction of sagittal synostosis is safe; decreases blood loss, operative time, and hospitalization costs; and provides excellent early surgical results.

Cranial Sutures↗
PubMed1998

Endoscopic treatment of carpal tunnel syndrome: a critical review.

OBJECT: The goal of this paper is to present a critical review of the endoscopic procedures currently in use for the treatment of carpal tunnel syndrome. Endoscopic techniques and outcomes are discussed. METHODS: An extensive review of published articles on the subject of endoscopic carpal tunnel release surgery is presented, encompassing six endoscopic techniques used to treat carpal tunnel syndrome. Since the first report in 1987, 7091 patients have undergone 8068 operations. The overall success rate has been 96.52%, with a complication rate of 2.67% and a failure rate of 2.61%. The mean time to return to work in patients not receiving Workers' Compensation was 17.8 days, ranging between 10.8 and 22.3 days. The most common complications were transient paresthesias of the ulnar and median nerves. Other complications included superficial palmar arch injuries, reflex sympathetic dystrophy, flexor tendon lacerations, and incomplete transverse carpal ligament division. In many studies in which open and endoscopic techniques were compared, it was reported that patients in the the latter group experienced significantly less pain and returned to work and activities of daily living earlier. CONCLUSIONS: Success and complication rates of endoscopic carpal tunnel release surgery are similar to those for standard open procedures.

Absenteeism↗
PubMed1998

Usefulness of endoscopy in craniofacial trauma.

To determine the extent of endoscopy utilized in craniofacial trauma, a questionnaire was mailed to 400 surgeons in the United States. A 40% response was obtained; 21.3% of the surgeons stated that they had used endoscopy to treat facial fractures; 33% of them had been in practice for 6 to 10 years, and 47% of those who had used endoscopy in craniofacial trauma were in full-time private practice. In facial fractures, endoscopes were used primarily to treat Le Fort fractures (55.9%), followed by zygomatic arch fractures (52.9%). Lack of accompanying instrumentation, such as appropriate drills, to use with the endoscope via small openings was cited as a significant problem; 46% of the respondents were unable to resolve it. Most respondents (55.6%) felt that if proper accompanying instrumentation were to be developed, endoscopes would become an integral component in the management of craniofacial trauma.

Attitude of Health Personnel↗
PubMed1997

Endoscopic treatment of carpal tunnel syndrome: a critical review.

An extensive review of published articles on the subject of endoscopic carpal tunnel release surgery is presented, encompassing six endoscopic techniques used to treat carpal tunnel syndrome. Since the first report in 1987, 7091 patients have undergone 8068 operations. The overall success rate has been 96.52%, with a complication rate of 2.67% and a failure rate of 2.61%. The mean time to return to work in patients not receiving Workers' Compensation was 17.8 days, ranging between 10.8 and 22.3 days. The most common complications were transient paresthesias of the ulnar and median nerves. Other complications included superficial palmar arch injuries, reflex sympathetic dystrophy, flexor tendon lacerations, and incomplete transverse carpal ligament division. All studies in which open and endoscopic techniques were compared reported that patients in the latter group experienced significantly less pain and returned to work and activities of daily living earlier. The reported success and complication rates of endoscopic carpal tunnel release surgery are similar to those for standard open procedures. Endoscopic techniques and outcomes are discussed.

Journal Article↗
PubMed1997

The effects of methylmethacrylate's hyperthermic polymerization on cerebral vascular permeability.

This study was undertaken to analyze the effects of significant hyperthermia (> 100 degrees C) associated with the polymerization of polymethlymethacrylate (PMM) on the permeability of the cerebral vasculature in rats. The method used to visualize the pial vasculature included the open pial window technique and epifluorescence microscopy. Results indicated that there is a significant increase in cerebral vascular permeability following in situ polymerization of PMM over the craniectomy site.

Animals↗