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Biomedical subjects

A Camacho

Publications and source records attributed to A Camacho.

At least 55 records · Page 3Linked to original sources
PubMed1992

Volumetric stereotactic resection of superficial and deep seated intraaxial brain lesions.

From 1984 to 1989 a total of 374 computer-assisted stereotactic resections based on computed tomography or magnetic resonance imaging were performed on 337 supratentorial and 37 infratentorial brain lesions. Computer-assisted stereotactic volumetric resection allows a more aggressive extirpation of tumours with less damaging of the adjacent brain tissue. This procedure is of most benefit in deep seated circumscribed lesions and of less benefit in infiltrating tumours such as high grade gliomas and in fibrillary astrocytomas located in essential brain areas.

Astrocytoma↗
PubMed1992

Antigen selection and presentation to protect against transmissible gastroenteritis coronavirus.

The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) has been determined and correlated with the physical structure. Four antigenic sites have been defined (A, B, C, and D). The sites involved in the neutralization of TGEV are: A, D, and B, sites A and D being antigenically dominant for TGEV neutralization in vitro. These two sites have specific properties of interest: site A is highly conserved and is present in coronaviruses of three animal species, and site D can be represented by synthetic peptides. Both sites might be relevant in protection in vivo. PRCV does not have sites B and C, due to a genomic deletion. Complex antigenic sites, i.e., conformation and glycosylation dependent sites, have been represented by simple mimotopes selected from a library expressing recombinant peptides with random sequences, or by anti-idiotypic internal image monoclonal antibodies. An epidemiological tree relating the TGEVs and PRCVs has been proposed. The estimated mutation fixation rate of 7 +/- 2 x 10(-4) substitutions per nucleotide and year indicates that TGEV related coronaviruses show similar variability to other RNA viruses. In order to induce secretory immunity, different segments of the S gene have been expressed using a virulent forms of Salmonella typhimurium and adenovirus. These vectors, with a tropism for Peyer's patches may be ideal candidates in protection against TGEV.

Amino Acid Sequence↗
PubMed1991

Protein p22 of African swine fever virus: an early structural protein that is incorporated into the membrane of infected cells.

The open reading frame K'177, located at the left end of the African swine fever virus genome, codes for an early induced structural protein of 22,000 Da (p22), which is released from the viral particle by the nonionic detergent n-octyl-beta-D-glucopyranoside under conditions that solubilize external viral structural proteins. The predicted amino acid sequence of the protein contains a hydrophobic region at its N-terminus with characteristics of a signal peptide and, at early times after virus infection of Vero cells, the protein can be detected in the cell membrane by immunolabeling.

Amino Acid Sequence↗
PubMed1989

Colloid cysts: experience with the management of 84 cases since the introduction of computed tomography.

A retrospective review of colloid cysts diagnosed from 1974 to 1986 emphasizes the presenting symptoms of these lesions, their surgical management, and the contribution of modern imaging techniques to their diagnosis and therapy. In this 12-year period, 84 patients (45 men and 39 women) had a colloid cyst diagnosed. The patients' mean age was 46 years (range, 7-82 years). Surgery was performed in 55 patients, 7 of whom had undergone prior surgery elsewhere. The surgical approaches used were transfrontal-transventricular, transcallosal, computer-assisted stereotactic aspiration and resection by stereotactic craniotomy, and shunting of cerebrospinal fluid without removal of the lesion. There was no operative mortality, but complications occurred in 15 patients (27%). Preoperative imaging showed hydrocephalus in 93% of the patients: severe in 43%, moderate in 36%, and mild in 14%. In the surgically treated group, the most common presenting symptoms were headache, change in mental status, ataxia, nausea and vomiting, visual disturbance, emotional lability/inappropriate affect, depersonalization, and hypersomnolence. Twenty-four patients for whom surgery was not recommended are being followed up closely. Most of these patients had normal ventricles. The symptoms in this group included headache, anxiety/nervousness, ataxia, memory impairment, visual disturbance, and seizures. Five autopsy cases of patients with colloid cysts were available during this period and were reviewed. Direct removal of colloid cysts can be accomplished with low morbidity and mortality, avoiding the frequent revisions and complications related to shunt procedures. There is a subgroup of colloid cysts that can be operated upon electively or followed up closely with serial imaging studies.

Adolescent↗
PubMed1989

Stereotaxic suboccipital transcerebellar biopsy of pontine mass lesions.

Twenty-six patients (16 male and 10 female) ranging in age from 5 to 68 years underwent suboccipital transcerebellar stereotaxic biopsy of mass lesions situated in the pons. Stereotaxic computerized tomography, magnetic resonance imaging, and angiographic data were obtained while the patient was positioned in an inverted custom stereotaxic head frame. The patients were then placed under general endotracheal anesthesia and positioned prone. Optimal trajectory planning utilized a transcerebellar route directed through the middle cerebellar peduncle, with target and entry points calculated to avoid vascular structures. No complications were encountered in the perioperative period when this technique was used. Histological diagnosis of the lesions revealed: astrocytomas in 14 patients, oligodendroglioma in one, ependymoma in one, arteriovenous malformations in two, radionecrosis in one, cryptococcal abscess in one, demyelinating disease in three, and infarctions in three. No consistent correlation could be made between radiographic characteristics and histological diagnoses. Empiric treatment of brain-stem lesions without tissue diagnosis based upon the radiological and clinical findings may result in inappropriate therapy administration. Alternatively, open operative procedures to obtain tissue require a visible surface abnormality to guide biopsy, and carry the risks of a major surgical procedure in already compromised patients. For these reasons the authors consider a suboccipital transcerebellar stereotaxic biopsy to be the diagnostic procedure of choice in the assessment of pontine mass lesions.

Adolescent↗
PubMed1986

Treatment and outcome of undifferentiated carcinoma of the nasopharynx in childhood: a 13-year experience.

Between 1970 and 1983, 22 pediatric patients diagnosed as having undifferentiated nasopharyngeal carcinoma (UNC) were treated at the National Children's Hospital of Costa Rica; primary tumor with local extension (T3-T4) was present in 45% of the patients, and metastasis of the cervical nodes (N1-N3) in 82%. Patients were divided into groups A and B according to the type of treatment received. A description of both groups is as follows. Ten patients were treated with 5,000 to 6,000 rads tumor dose to the primary and a 5,125-rad dose was administered to the lower neck between 1970 and 1977 (group A). Six patients received postradiation therapy with cyclophosphamide and vincristine and two patients also received 5-fluorouracil. The outcome in group A was as follows: four (40%) failed to respond, six (60%) achieved full remission initially with two subsequent relapses, and the remaining four are still alive and free of relapse after 90 to 160 months (average 130) (two were treated with Co60 alone and two with chemotherapy. Twelve patients were treated with chemotherapy pre- and postradiation with CPM and adriamycin for a total of 12 months (group B) between 1978 and 1984. All (100%) achieved complete initial remission; two patients relapsed and died. Ten patients have remained in relapse-free survival for 18-67 months (median 32). Though this is not a controlled study, our experience indicates that pre- and postradiation chemotherapy is effective in prolonging the disease-free survival in UNC and may allow a decrease of the radiation tumor dose.

Adolescent↗
PubMed1985

Autonomic responsiveness to affective visual stimulation in temporal lobe epilepsy.

Patients with temporal lobe epilepsy (TLE) have been posited by some to manifest a syndrome of interictal personality and behavioral change. Furthermore, this syndrome has been attributed to an underlying mechanism--enhanced affective responsiveness. The purpose of this investigation was to determine whether patients with TLE manifest increased emotional responsiveness relative to appropriate controls. Patients with TLE (n = 23) were compared with non-TLE (n = 7) and healthy controls (n = 16) as to their autonomic nervous system responsiveness to an emotionally stressing film. No differences were found among the groups. These results are related to the larger literature concerning epilepsy and psychopathology.

Adult↗
PubMed1985

[111In]oxine labelling of polymorphonuclear leucocytes: doubts concerning elution and effects on cell behaviour.

Polymorphonuclear leucocytes (PMN) from normal human subjects were labelled with [111In]oxine (20 muCi 10(8) cells). In the presence of 20% autologous serum (AS), dissociation of 111In from the cells resulted in mean losses of radioactivity of 13% at 3 h and 30% at 24 h. Adherence of 111In-labelled PMN to cultured porcine endothelial monolayers was increased by 40.7 +/- 31.6% after 60 min incubation in 20% AS at 37 degrees C when compared with unlabelled cells. Phagocytosis and intracellular killing of Candida albicans were unaltered by labelling. Elution of 111In from labelled PMN together with enhanced adhesiveness may have important implications for the study of PMN kinetics and the investigation of inflammatory disease.

Cell Adhesion↗
PubMed1981

Horseradish peroxidase study in rat of the neural connections of the organum vasculosum of the lamina terminalis.

Using highly localized injections by a transbuccal approach a study of the afferent and efferent connections of the organum vasculosum laminae terminalis (OVLT) with horseradish peroxidase (HRP) methods was carried out. The results showed that the OVLT has direct connections to several hypothalamic nuclei (anterior, preoptic, lateral preoptic, ventromedial nucleus) and to extrahypothalamic (central gray, locus coeruleus, subfornical organ) regions. There was not a direct projection from the supraoptic nucleus. Some of these connections may be involved in the functional actions of the OVLT observed after central injections of angiotensin II.

Afferent Pathways↗
PubMed1981

Separation of drinking and pressor responses to central angiotensin by monoamines.

This study investigated the neurotransmitters involved in the increase in blood pressure and drinking produced when angiotension II is injected intraventricularly (ivt). Using pharmacologic manipulations of the monoamines norepinephrine, dopamine, and serotonin it has been possible to separate the pressor response from dipsogenic responses to angiotension II. Alpha-adrenergic blockade with phentolamine restricted to the brain blocked the pressor response to angiotensin II in a dose-related manner, while drinking remained unaffected. Norepinephrine alone, injected into the ventricles elevated blood pressure, but did not produce drinking. The norepinephrine effect was also blocked by phentolamine by the same ventricular route. Other monoamines were not involved. Dopamine alone did not produce thirst. Cardiovascular effects with dopamine were observed only with large doses. The dopaminergic agonist apomorphine produced no change in blood pressure or drinking. Reduction of central serotonin stores by p-chlorophenylalanine intraperitoneally or 5,7-dihydroxytryptamine intraventricularly had no effect on the pressor or dipsogenic effects of angiotensin II. The serotonin agonist N,N-dimethyl-5-methoxytryptamine ivt did not produce a rise in blood pressure or drinking. It is concluded that the pressor effect of angiotensin II, but not the drinking effect is mediated by noradrenergic stimulation of alpha-receptors. The drinking response does not appear to be mediated by the monoamines.

Angiotensin II↗
PubMed1979

Order of assembly of the lower collar and the tail proteins of Bacillus subtilis bacteriophage phi 29.

Extracts obtained after restrictive infection of Bacillus subtilis with mutants in cistron 11 of bacteriophage phi 29 are complemented in vitro by extract donors of the lower collar protein (p11). Purified 11- heads, containing the major capsid protein (p8), the fiber protein (p8.5), the upper collar protein (p10), and the virus DNA, can be also complemented in vitro to produce infective virus. This result suggests that 11- heads are intermediates in phage phi 29 morphogenesis. The order of assembly of the lower collar protein p11 and the tail protein p9 was determined in vitro in two complementation steps. The results obtained indicate that the lower collar protein is assembled before the tail protein.

Bacillus subtilis↗