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Biomedical subjects

A Camacho

Publications and source records attributed to A Camacho.

72 records · Page 4Linked to original sources
PubMed1978

Transformation of hamster embryo fibroblasts by a specific fragment of the herpes simplex virus genome.

Isolated restriction endonuclease fragments of the herpes simplex virus type 1 (HSV-1) genome were introduced into hamster embryo cells to identify DNA sequences capable to transforming the cells with respect to acquisition of properties correlated with tumorigenicity. One of the fragments generated by cleavage of HSV-1 DNA with the restriction endonuclease Xba I was found to induce transformation at a frequency of about 10 colonies per quantity of fragment recovered from 1 microgram of uncut DNA; fractions containing the other Xba I fragments failed to induce transformation reproducibly, although occasional colonies were detected. The fragment with transforming activity (Xba I-F) is 15.5 X 10(6) daltons in molecular weight and is located between 0.30 and 0.45 map units on the HSV-1 genome. The Xba I-F transformants obtained were selected for their ability to replicate in low concentrations of serum; in addition, they were found to attain high saturation densities in the presence of 10% serum and to form colonies in semisolid medium. Moreover, the transformed cells produced at least one of the viral gene products (a membrane glycoprotein) encoded in the fragment used for transformation, indicating not only that viral DNA was incorporated into the cells, but also that viral genes were expressed.

Antigens, Viral↗
PubMed1977

Assembly of Bacillus subtilis phage phi29. 1. Mutants in the cistrons coding for the structural proteins.

The effect of mutations in the cistrons coding for the phage structural proteins has been studied by analyzing the phage-related structures accumulated after restrictive infection. Infection with susmutants in cistron 8, lacking both the major head and the fiber protein, does not produce any phage-related structure, suggesting a single route for the assembly of phage phi29; infection with ts mutants in this cistron produces isometric particles. Mutants is cistron 9, coding for the tail protein, TP1, produce DNA-free prolate heads with an internal core; these particles are abortive and contain the head proteins HPO, HP1 and HP3, the upper collar protein NP2 and the nonstructural proteins p7, p15 and p16. Mutants in cistron 10, coding for the upper collar protein, NP2, produce DNA-free isometric heads also with an internal core; they contain the head proteins and the nonstructural protein p7, suggesting that this protein forms the internal core. Mutants in cistrons 11 and 12, coding for the lower collar protein, NP3, and the neck appendages, NP1, respectively, give rise to the formation of DNA-containing normal capsids and DNA-free prolate particles, more rounded at the corners than the normal capsids and with an internal core; the DNA-containing 11-particles are formed by the head proteins and the upper collar protein; the DNA-free 11-particles contain, besides these proteins, the nonstructural protein p7 and a small amount of proteins p15 and 16. The DNA-containing 12-particles have all the normal phage structural proteins except the neck appendages, formed by protein NP1; the DNA-free particles are similar to the DNA-free 11-particles. After restricitive infection mutant sus14(1241) has a delayed lysis phenotype and produces a phage burst higher than normal, after artificial lysis. It produces DNA-containing particles, identical to wild-type phage, which have all the normal phage structural proteins, and DNA-free prolate particles, more rounded at the corners than the final phage particles and with an internal core; the last particles contain the same proteins as the DNA-free 11 or 12-particles. These particles could represent a prohead state, ready for DNA encapsulation. None of the DNA-containing particles have the nonstructural proteins p7, p15 or p16, suggesting that these proteins are released from the proheads upon DNA encapsulation.

Bacillus subtilis↗
PubMed1977

Assembly of Bacillus subtilis phage phe29. 2. Mutants in the cistrons coding for the non-structural proteins.

The effect on phage morphogenesis of sus mutations in the cistrons coding for nonstructural proteins has been studied. Mutants in three cistrons analyzed that are involved in phage DNA synthesis, as well as in cistron 16 which codes for a late nonstructural protein, produce prolate capsids which are more rounded at the corners than complete phage heads and have an internal core; they contain the head proteins, the upper collar protein and protein p7, not present in mature phage particles. Mutants in cistron 7 do not produce capsids nor other phage-related structures; this result and the presence of p7 in phage capsids suggest an essential role in capsid assembly for this protein. The protein product of cistron 13 is probably needed for a stable DNA encapsulation since mutants in this cistron produce mainly DNA-free complete phage particles and only about 10% of uninfective DNA-containing complete phage. Cistron 15 codes for a late, partially dispensable, nonstructural protein which is present in the DNA-free capsids produced after infection with the delayed-lysis mutant sus14(1242), used as the wild-type control, or with mutants in cistrons 9, 11,12 and 13. Proteins p15 and p16 are probably involved in the encapsulation of viral DNA in a prohead.

Bacillus subtilis↗
PubMed1976

Structure and assembly of phage phi29.

Bacteriophage phi29 is a small, morphologically complex, virus with a DNA of molecular mass 12 X 10(6). The most likely structure of the head of phi29 consists of two fivefold symmetric end-caps based on T = 1 icosahedral symmetry, separated by an equatorial row of 5 hexamers. The eighteen genes identified in phi29 genome have been mapped and, in some cases, the gene products have been identified. Five linked genes, four coding for structural proteins (G, A, E, H) and one coding for a non-structural protein (J), are essential to determine the normal shape of the capsid. Protein pJ may be a scaffolding protein. An account of the effects of mutations in phi29 genes is given.

Bacillus subtilis↗
PubMed1976

Bacillus subtilis phage phi29. Characterization of gene products and functions.

A total of 22 phi29-induced proteins have been resolved by slab gel electrophoresis; two of these proteins are the precursor and product fragment, respectively, in the synthesis of the neck appendage protein of the phage. The protein products of 10 out of the 17 cistrons detected in the genome of phage phi29 have been identified. Mutants in two other cistrons fail to synthesize two proteins. Mutants in six genes do not synthesize phage DNA. A cistron, probably involved in the final lysis of the infected bacteria, has been found. Mutants in this gene give place, under restrictive conditions, to delayed lysis and produce, after artificial lysis, a burst size similar or higher than that obtained after wild-type phage infection.

Bacillus subtilis↗
PubMedDate not supplied

Platelets and psychiatry: lessons learned from old and new studies.

Platelets play an important role not only in hemostasis but also in the pathophysiology of coronary artery disease. The complex interactions among the vascular endothelium, platelets, and blood components are one of the most exciting research areas today. This review addresses some fundamentals of platelet physiology and examines why platelets are interesting probes for neurophysiology. Results of current studies suggest that platelets are affected by diverse stressors, including psychological ones, and that platelets offer an interesting vantage point for understanding the neurophysiology of various psychiatric disorders. We also describe how platelets have been used for various types of research, including studies of stress associated with cardiovascular disease and studies of platelets in psychopharmacological research. Finally, we examine some of the psychiatric literature related to platelets; these studies range from case studies from the 1920s to contemporary experimental studies.

Blood Platelets↗
PubMedDate not supplied

[Echocardiography-guided temporary implantation of electrode catheters: an alternative with reliable results even during prolonged use].

OBJECTIVE: Two-dimensional echocardiography (2D-ECO) evaluation as an alternative guidance technique during temporary pacing wire placement. DESIGN: Prospective evaluation of implantation and pacing parameters. SETTING: Admission from the Emergency Room and patients studied in the Cardiology Department of the Hospital Distrital in Faro. PATIENTS: Twenty patients with indication for temporary cardiac pacing during, at least, twelve hours (H). Fluoroscopy equipment shouldn't be readily available for implantation. INTERVENTIONS: The mean ages of the 20 pts. (14 men and 6 women) were 71.90 +/- 2.12 years. All pts. had a temporary pacing lead implantation under 2D-ECO guidance. Indications for cardiac pacing were: second or complete atrioventricular block (17 pts.), new onset bifascicular bundle branch block during anterior acute myocardial infarction (1 patient) and sick sinus syndrome (2 pts.). The transvenous route of approach has been the right internal jugular in all the cases and venipuncture time accounts for the calculation of total implantation time. MEASUREMENTS AND RESULTS: Ventricular capture was achieved in all pts., with stable stimulation thresholds. The mean implantation time was +/- 9.21 minutes and the mean acute stimulation threshold 0.33 +/- 0.20 V and 0.65 +/- 0.35 mA. The mean voltage of the intracavitary QRS was 11.15 +/- 2.95 mV and the mean lead resistance was 851.33 +/- 194.04 Ohms. The mean utilization time of the pacing leads was 95.15 +/- 87.49 H and the mean stimulation threshold during lead explanation was 0.85 +/- 0.47 mA. The only complication appearing during our study has been one lead dislodgment (5%), 72 h after implantation, placed again with the guidance of 2D-ECO and used during 216 H without further complications. Subcostal 2D-ECO window alone was used in 85% of the pts. but in the remaining (15%), it was insufficient and an apical window was needed too. CONCLUSIONS: The 2D-ECO was an efficient alternative technique of guidance during temporary lead placement, ensuring satisfactory longterm pacing and sensing. Our results indicate that 2D-ECO may be the best alternative control for urgent lead implantation whenever fluoroscopic facilities are remote or logistically not convenient.

Aged↗
PubMedDate not supplied

[Biochemical genetic markers in the study of the larvivorous fish Cubanichthys cubensis (Eigenmann, 1903) (Teleostei: Cyprinodontidae) used as a bioregulator agent of culicids in Cuba].

By means of starch gel electrophoresis, samples were analyzed from 3 populations (Batabanó, Guanímar and Isle of Youth) of Cubanichthys cubensis adult fishes, bioregulators of mosquito larvae. A study was made of six protein systems which are considered to be under the genetic regulation of 13 loci, 3 of which are polymorphic. The electrophoretic characteristics of each of them are described. By means of the genotypical frequencies of the polymorphic systems (PGI-1, PGI-2, and PGM), the 3 populations were compared with the use of the statistical G. No significant differences were found.

Animals↗
PubMedDate not supplied

[Chronic hemodialysis: risk factors for intra-dialytic hypotension (IDH)].

Haemodialysis is the most used among the different renal function replacement methods. Although the survival is acceptable the mobility is important; intradialytic hypotension is a main cause of such mobility. In this study which included stable chronic haemodialysis patients, the authors evaluate risk factors for IDH. Advanced age, female sex and autonomic insufficiency are risk factors for IDH. Patients with IDH had more serious ventricular arrhythmias, but a cause-effect relationship was not demonstrated.

Aged↗
PubMedDate not supplied

[Lymphoepithelioma of the pharynx in children].

Through a period of thirteen years, eleven patients with pharyngeal lymphoepithelioma were treated at the Hospital Nacional de Niños, San José, Costa Rica. This represents 2.5% of all malignant tumors observed in the same period. Histologically, 10 cases were of the type described by Regaud and only one was of the Schmincke's type. Four patients were treated with cobalt only and the other seven received Co60 plus chemotherapy. Two patients of the first group are alive and without evidences of tumor 96 months later. Four of the seven patients of the second group have been incomplete remission for 5, 9, 24 and 96 months. All the patients who had partial remission and all those who relapsed died because of infiltration to the basis of the skull and/or metastases to long bones. All patients who had complete remission and did not have a relapse through a 24 month period, are alive and without evidences of tumor. Metastases to cervical lymph nodes at the moment of diagnosis did not influence the response to treatment or the prognosis. Three out of 5 patients with infiltration to the basis of the skull at the initial examination died. The other two are alive at 9 and 96 months post-treatment.

Adolescent↗
PubMedDate not supplied

[Results of combined therapy in rhabdomyosarcoma in children].

In a study of rhabdomyosarcoma in children, 16 cases were treated and followed since 1971. Eight patients were staged I and II A and presented a mean survival time of 52 and 21 months respectively, whereas the remaining 8 patients were staged II B and III with a mean survival time of 20 and 9 months respectively. Of the 16 patients treated, 10 (62.5%) continue survival with an overall median survival time of 25 months. It is suggested that an early diagnosis and combined treatment including surgery, radiotherapy and chemotherapy with vincristine, cyclophosphamide and actinomicin and possibly adriamycin as a fourth drug, will give patients in underdeveloped countries, similar survivals and relief as those observed in developed countries. It is apparent that a multidisciplinary medical team is more important than the magnitud of economical resources.

Antineoplastic Agents↗