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Biomedical subjects

J Garcia

Publications and source records attributed to J Garcia.

At least 145 records · Page 8Linked to original sources
PubMed1997

[Synchronous surgical removal of esophageal and pulmonary cancer by endoscopic mucosectomy and video-assisted lobectomy through minimal thoracotomy].

Authors report a case of a 75 year old, male patient suffering from an early stage squamous esophageal cancer and a synchronous adenocarcinoma of the lung. The patient was operated on simultaneously at the same setting: the esophageal tumour was taken out by endoscopic mucosectomy, whereas the pulmonary cancer was removed by video assisted minimal thoracotomy. The definitive histological diagnosis was: squamous cell cancer (muscular mucosal cancer) (pT1) of the esophageal lesion and adenosquamous cancer (pT2) of the lung. Authors draw attention on the significance of the early diagnosis of malignant tumours, and in this case minimally invasive endoscopic procedures can be successfully performed.

Adenocarcinoma↗
PubMed1997

Solution conformation of an abasic DNA undecamer duplex d(CGCACXCACGC) x d(GCGTGTGTGCG): the unpaired thymine stacks inside the helix.

The three-dimensional structural analysis of DNA undecamer 5'd(C1G2C3A4C5X6C7A8C9G10C11)3', 3'd(G22C21G20T19G18T17G16T15G14C13G12)5' duplex in which the X residue is a modified abasic site [3-hydroxy-2-(hydroxymethyl)tetrahydrofuran] has been performed using NOESY, DQFCOSY, TOCSY, and 31P-1H HSQC-TOCSY spectra in relation with molecular dynamics simulations. A total of 249 distances and 224 dihedral angles were used for construction. The optimal distances were calculated using the complete relaxation matrix method from hybrid matrices which were built with the experimental NOE intensities and additional data derived from either standard A- or B-DNA. Six independent refined structures starting from canonical A- and B-DNA were determined on the basis of the NMR data, and all converged to a single family with average rms deviations below 0.6 A and final NOE Rx factors of 0.055 +/- 0.03. A satisfactory agreement was obtained between measured NOE intensities and those resulting from full relaxation matrix calculations. A single intrahelical form of right-handed DNA duplex is observed; the aromatic base of residue T17 opposite the abasic site is stacked inside the helix. No clear correlation was detected between the C5 and C7 residues, excluding their proximity and the looping out of the abasic site. The abasic site induces a kink of about 30 degrees in the DNA duplex. This kink allows the formation of a bifurcated hydrogen bond between the amino protons of C5 and the O4 oxygen of T17. A detailed analysis of the final structures and their comparison with previous studies of abasic site lesions are described.

DNA↗
PubMed1997

NMR and molecular modeling studies of the interaction of artificial AP lyases with a DNA duplex containing an apurinic abasic site model.

Tailor-made molecules, DTAc and ATAc, that incorporate a nucleic base (adenine or 2,6-diaminopurine) linked by a diamino chain to an intercalator (9-amino-6-chloro-2-methoxyacridine) selectively recognize and efficiently cleave abasic sites in DNA via a beta-elimination reaction. The three-dimensional structure of the complexes of DTAc and ATAc bound to a DNA undecamer, the 5'd(C1G2C3A4C5X6C7A8C9G10C11)3' x 3'd(G22C21G20T19G18T17G16T15G14C13G12)5' duplex in which the X residue is a stable abasic site [3-hydroxy-2-(hydroxymethyl)tetrahydrofuran], has been studied by combined NMR-energy minimization methods. Analysis of the NMR spectra reveals that DTAc and ATAc interact with a very similar fashion and form two different complexes with DNA, present in a ratio of 70/30 (+/-10). In both complexes, the acridine ring intercalates exclusively between the C3 x G20 and A4 x T19 base pairs, the linker is located in the minor groove, and the base moiety docks in the abasic site. The principal difference between the major and the minor complexes consists of a 180 degrees rotation of the acridine ring around the Acr-C-N bond within the same intercalation site. Molecular modeling studies with few intermolecular ligand-DNA restraints were used to investigate the geometry of the base pair formed between the diaminopurine of DTAc and the T17 ring. The most energetically favored complex has the 2,6-diaminopurine of DTAc base paired with the T17 ring in a Hoogsteen conformation. The models DTAc and ATAc are also discussed as nuclease mimics and cleaving agents at abasic sites.

DNA↗
PubMed1997

Role of MRI in the diagnosis of insufficiency fractures of the sacrum and acetabular roof.

OBJECTIVE: To review the risk factors and the radiological appearance of insufficiency fractures of the sacrum and acetabular roof. DESIGN AND PATIENTS: Twenty patients with sacral and acetabular roof insufficiency fractures were reviewed retrospectively. There were 16 women (80%) and 4 males (age range 48-86 years, excluding an 8-year-old boy). Thirteen patients had a known tumour, and nine had received pelvic irradiation. All patients, except one who was asymptomatic, presented with low back or hip pain. In patients with a known tumor, metastases were suspected. Plain radiography (20), bone scintigrams (16), MR examinations (20), and bone densitometry (14) were performed. Nine patients also each had a CT scan. RESULTS AND CONCLUSIONS: In three cases the CT scan performed 10-25 days after onset of symptoms was interpreted as normal. MR examination performed a few days after the CT scan showed in each of these three patients a fracture line with a band of edema. Scintigraphy was very sensitive, but the H-shaped pattern of sacral uptake, specific for an insufficiency fracture, was detected in only three of 16 cases. The earliest MR sign was medullary edema, seen as early as 18 days after the onset of symptoms. On spin echo (SE) T1-weighted images (T1WI), the hypointense signal of edema could mask a fracture line. On SE T2WI the fracture line could be detected within the hyperintense edema (10 of 17 patients with examinations including SE T2WI). However, in four patients a fracture of the sacrum was not seen on T2WI, these having been obtained in the axial plane. For this reason, intravenous gadolinium was injected, revealing a fracture line in 12 of 14 examinations, or fat suppression sequences were performed, revealing a fracture line in five of five cases. The total number of fractures detected was 17 [15 fractures of the sacrum (bilateral in 10 cases) and two of the acetabular roof]. At a later stage, the edema resolved and the fracture was clearly seen. The two cases of fracture of the acetabular roof were easily recognized at MRI, particularly in the sagittal plane.

Acetabulum↗
PubMed1997

Gouty tophus simulating soft tissue tumor in a heart transplant recipient.

Gouty arthritis is the most frequent rheumatological complication among cyclosporine-treated organ transplant recipients. We report one case of pseudotumoral intramuscular tophaceous deposit of the forearm, in a heart transplant patient with a history of traumatic wound to the same area 17 years previously, and with no known arthritis.

Adult↗
PubMed1997

Is operating room resuscitation a way to save time?

BACKGROUND: Direct admission to the operating room (OR) can shorten the time to incision. A protocol for operating room resuscitation was established with patient triage based on (1) cardiac arrest, (2) hypotension unresponsive to field fluid resuscitation, or (3) uncontrolled external hemorrhage. METHODS: Operating room resuscitation over 11 years was reviewed to determine whether the triage criteria correctly identified patients requiring operation. Survival was analyzed and compared with the probability of survival (Ps) determined at the scene. RESULTS: Operating room resuscitation patients were more likely to require a major operation regardless of mechanism of injury. Of 476 patients with penetrating injury, 170 patients had persistent low blood pressure (<90 mm Hg), and 146 (85.9%) of these required major operative intervention. The mean time to incision in this group was 21.7-67.5 minutes less than for patients not receiving OR resuscitation. Observed survival was significantly greater than that predicted for this group. CONCLUSIONS: Field triage criteria are able to reliably identify patients who require immediate major operative intervention. Direct admission to the OR results in a more timely initiation of operative therapy for patients requiring emergency surgical procedures.

Adult↗
PubMed1997

Chronic pain states: invasive procedures.

OBJECTIVE: To provide a review of chronic pain states, focusing on neuroanatomic pathways and their influence on treatment strategies (part 2 of a two-part series). DATA SOURCE: A thorough literature review of published articles available in Medline from 1966 to 1996 on the topic of pain management, including diagnosis, pathophysiology, interventions, and treatment. CONCLUSIONS: Understanding the pathophysiology of chronic pain and the role of chemical mediators, such as enkephalins, norepinephrine, serotonin, and substance P, may improve pain management. As a result, pain control measures can target inhibition of the descending pain modulation pathways of the spinal cord, in addition to the peripheral or central actions of traditional analgesics. Fewer ablative surgical interventions are performed for pain control, because they often provide only temporary relief at the expense of significant permanent neurological deficits. However, there are more augmentative procedures now available for the patient with intractable and unresponsive pain, although referral to specialized pain clinics may benefit particularly difficult cases.

Chronic Disease↗
PubMed1997

Chronic pain states: pathophysiology and medical therapy.

OBJECTIVE: The pathophysiology and management of chronic pain are reviewed in this two-part article, with an emphasis on pharmacological therapies and surgical interventions. DATA SOURCES: A thorough literature review of published articles available in Medline from 1966 to 1996 on the topic of pain management, including diagnosis, pathophysiology, interventions, and treatment. CONCLUSIONS: Despite the development of new instruments and treatments to assess and manage pain, chronic pain is often poorly understood and inadequately addressed. Caregivers often lack sufficient skills to intervene promptly and effectively. Traditionally, drug therapy has relied on the nonsteroidal antiinflammatory drugs (NSAIDs) and opioid analgesics for chronic nociceptive pain. A newer analgesic choice for moderate to moderately severe pain is tramadol, a centrally acting agent with at least two complementary mechanisms of action and minimal gastrointestinal or renal toxicity. Adjuvant agents, including tricyclic antidepressants (TCAs), anticonvulsants, and local anesthetics, also help manage chronic neuropathic pain. Although significant advances in the understanding of chronic pain and its pathophysiological mechanisms and newer techniques (noninvasive and invasive) for chronic pain management have become available, reduced patient morbidity and improved quality of life may only be realized with an improved understanding of available resources.

Analgesics↗
PubMed1997

Making sense of randomization; responses of parents of critically ill babies to random allocation of treatment in a clinical trial.

Randomized controlled trials (RCTs) are widely accepted by the scientific community as the most rigorous way of evaluating interventions in health care. Although their central feature, random allocation of treatment, is generally seen as methodologically appropriate, its application has caused much debate amongst health professionals and ethicists. This paper describes the views of parents who consented that their critically ill newborn baby should be enrolled in a neonatal trial. In-depth interviews were used to determine their response to the trial and randomization. The nature of the trial was often poorly understood. The random basis of the allocation of treatment and the rationale behind this approach were also problematic issues. Some parents did not perceive a random element in the process at all. These findings advance understanding of the perceptions of trial participants and raise important issues for those concerned with RCTs. Greater understanding of participants' views provides the potential to improve the management of future trials and so the experience of those agreeing to take part.

Adult↗
PubMed1997

Panic disorder and agoraphobia in consecutively referred children and adolescents.

OBJECTIVE: This report examines the clinical features and correlates of juvenile panic disorder in referred children and adolescents to test specific hypotheses about its relationship with adult panic disorder. METHOD: The sample consisted of consecutively referred children and adolescents (N = 472) comprehensively evaluated with structured diagnostic interviews, cognitive tests, and psychosocial assessments. RESULTS: Panic disorder was identified in 6% and agoraphobia in 15% of psychiatrically referred children and adolescents. Children meeting criteria for panic disorder also frequently met criteria for agoraphobia. The latter disorder was more prevalent and had an earlier age at onset than panic disorder. Children with panic disorder and those with agoraphobia had similar correlates with frequent comorbidity with other anxiety and mood disorders. A high level of comorbidity with disruptive disorders was also identified. CONCLUSIONS: These results support the hypothesis of continuity between the juvenile and the adult form of panic disorder. However, the high level of comorbidity with disruptive behavior disorders also suggests developmentally specific discontinuities between juveniles and adults with panic disorder.

Adolescent↗
PubMed1997

Epitope mapping of the nucleocapsid protein of European and North American isolates of porcine reproductive and respiratory syndrome virus.

Two major genotypes of porcine reproductive and respiratory syndrome virus (PRRSV) have been described, which correspond to the European and North American isolates. PRRSV nucleocapsid (N) protein has been identified as the most immunodominant viral protein. The N genes from two PRRSV isolates, Olot/91 (European) and Québec 807/94 (North American), were cloned and expressed in: (i) baculovirus under the control of the polyhedrin promoter and (ii) Escherichia coli using the pET3x system. The N protein from both isolates was expressed much more efficiently in E. coli as a fusion protein than in baculovirus. The antigenicity of the protein was similar in both systems and it was recognized by a collection of 48 PRRSV-positive pig sera. The antigenic structure of the PRRSV N protein was investigated using seven monoclonal antibodies (MAbs) and overlapping fragments of the protein expressed in E. coli. Four MAbs recognized two discontinuous epitopes that were present in the partially folded protein, or at least a large fragment comprising the first 78 residues. The other three MAbs revealed the presence of a common antigenic site localized in the central region of the protein (amino acids 50-66). This region is well conserved among different isolates of European and North American origin and is the most hydrophilic region of the protein. However, this epitope, although recognized by the MAbs and many pig sera, is not useful for diagnostic purposes. Moreover, none of the N protein fragments were able to mimic the antigenicity of the entire protein.

Amino Acid Sequence↗