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Biomedical subjects

J Link

Publications and source records attributed to J Link.

At least 145 records · Page 8Linked to original sources
PubMed1994

[Densitometry in suspected preclinical osteoporosis: quantitative computerized tomography versus dual energy roentgen absorptiometry].

The bone mineral density of 85 patients with suspicion of a preclinical osteoporosis was measured at the lumbar spine by using quantitative computed tomography (QCT) in single-energy technique (SEQCT) and dual-energy technique (DEQCT) as well as by using dual-energy X-ray absorptiometry (DEXA). Additionally, the bone density of 63 of these patients was measured at the left femoral neck using DEXA. DEQCT und DEXA of the lumbar spine showed only a moderate correlation (R = 0.75) and differed considerably concerning the classification of the patients as normals or individuals with a mineral deficit when compared with age-matched normals (relative mineral deficit). The DEXA proved to be susceptible to degenerative alterations of the lumbar spine. Because of the extremely low dose of radiation and the good reproducibility the DEXA could nevertheless be recommended as a method for the long-time progress control especially for younger patients. SEQCT and DEQCT showed a very strong correlation (R = 0.98). The SEQCT with its lower dose of radiation should be sufficient for a long-time progress control and in many cases also for the initial diagnostics. Significant but only moderate correlations were found between the bone density at the femoral neck and the DEXA or DEQCT results (R = 0.68 respectively R = 0.63) for the lumbar spine, so that the linear regression did not render any useable approximations. Sufficiently exact information about the mineralization status of a certain skeletal site can only be obtained by direct measurement.

Absorptiometry, Photon↗
PubMed1993

[Extrathoracic prolapse of the pulmonary parenchyma after a bout of coughing with spontaneous serial rib fractures].

A 54-year-old man with an feverish infection of the lower respiratory tract developed severe pain in the lateral and basal part of the left thorax after a severe coughing bout. A haematoma occurred at the site and it looked as though tissue evaginated at that spot on coughing and pressing. The clinical diagnosis was pneumonia and abnormal mobility of the eighth to tenth rib on the left with crepitations. The chest radiograph demonstrated fractures of these ribs and extrathoracic sickle-shaped collection of air in the left laterobasal area. Computed tomography additionally showed prolapse of pulmonary tissue on pressing. This was thus a case of "cough fracture", complicated by herniation of lung tissue. There was no evidence of incarceration of lung tissue and, as the patient was very obese, surgery was not indicated. Symptoms and signs of infection regressed on symptomatic and antibiotic treatment. The rib fractures healed as pseudoarthroses. Lung tissue prolapse on pressing was still present 3 months later.

Cough↗
PubMed1993

The mechanisms and prognostic significance of seminal vesicle involvement by prostate cancer.

To assess the mechanisms and prognostic significance of seminal vesicle involvement (SVI) by prostatic adenocarcinoma, we analyzed 312 radical prostatectomy specimens obtained from patients with T1-T3 prostate cancer. Detailed pathological examination demonstrated three patterns of SVI. Type I involvement was direct spread along the ejaculatory duct complex into the seminal vesicles. Type II involvement was spread outside of the prostate, through the capsule, and then into the seminal vesicle. Type III involvement was characterized by the finding of isolated deposits of cancer in the seminal vesicle with no contiguous primary cancer in the prostate. We found SVI in 64 patients (21%), who have been followed for a mean of 31 months (range 1-101). A defining criterion for progression was clinically apparent local or distant recurrence or a postoperative serum prostate specific antigen (PSA) > or = 0.4 ng/ml (Hybritech). Type I SVI was found in 17 (26%), Type II in 21 (33%), and Type III in 8 (13%) cases. In 18 patients (28%), the pattern of SVI appeared to be a combination of types I and II (categorized as Type I+II). Type III (isolated metastasis) SVI was associated with significantly smaller cancers (median, 3.13 vs. 6.7 cc; p < 0.0005) and fewer positive margins (0 vs. 32%; p = 0.05) than in other types. Type II SVI, with direct extension through the capsule, was associated with a significantly higher risk of lymph node metastasis (8 vs. 33%; p < 0.05). When patients with lymph node metastases were excluded, there was a trend toward a more favorable prognosis (p = 0.09) for patients with type III SVI than with other types. Overall, patients with type III SVI had a progression-free survival rate similar to that of 83 patients with extracapsular extension without SVI. We conclude that the prognostic significance of SVI may not be uniformly ominous; instead, it may depend on the specific mechanism of involvement and the pathologic features of the primary tumor.

Adenocarcinoma↗
PubMed1993

[The action of atracurium and vecuronium in chronically hemodialyzed patients].

UNLABELLED: Reports on the duration of action of atracurium (Atr) and vecuronium (Vec) in patients with renal failure are contradictory. It is either stated that the duration is equal for both relaxants or that Atr acts for a longer duration. Because of these conflicting results, we measured the times for latency (tL), onset (tA), duration of action (tW), and recovery (tE) for both agents. METHODS: Fourty patients with end-stage renal failure on chronic haemodialysis were randomly assigned to receive either Atr (0.4 mg.kg-1 BW) or Vec (0.08 mg.kg-1 BW). After induction with thiopentone and 0.1 mg fentanyl, anaesthesia was maintained with nitrous oxide and 1 vol.% ethrane and expiratory CO2 partial pressure was kept between 4.6 and 4.9 kPa. If the twitch height of T1 regained 25% of the pre-relaxation value, 20% of the initial relaxant bolus was injected. Relaxation was monitored with a relaxograph after calibration of the device. After testing for a normal distribution, statistical analysis was done by Student's t-test. A value of P < or = 0.05 was chosen for statistical significance. RESULTS: There were no significant differences regarding tL (Atr: 1.0 +/- 0.5 min; Vec: 1.1 +/- 0.5 min) and tA (Atr: 5.5 +/- 2.1 min; Vec 4.1 +/- 2.4 min); tW (Atr: 21.3 +/- 13.1 min; Vec 31.7 +/- 15.6 min) and tE (Atr: 19.0 +/- 9.0 min; Vec 30.1 +/- 19.0) were significantly different. DISCUSSION: Our results are not in accordance with those authors who found in comparison with Atr an equal or shorter duration of action for Vec in patients with renal failure. If the duration of action is equal in subjects with no renal insufficiency, our measurements are in accordance with kinetic evaluations showing the same clearance and half-life for Atr in patients with and without renal insufficiency, but 40% diminished clearance and 60% prolonged half-life for Vec in renal insufficiency.

Adult↗
PubMed1993

Experimental studies of DL-polylactic acid biodegradable plates and screws in rabbits: computed tomography and molecular weight loss.

A series of studies were designed to assess the potential of biodegradable DL-polylactic acid (DL-PLA) plates and screws for use in craniofacial surgery. We report on computed tomography (CT) scanning for visualization and postoperative follow-up and the short-term degradation sequelae of a biodegradable plate and screw system in an experimental animal model. Fractures of the nasal bones were created in 20 adult New Zealand white rabbits and rigidly fixed bilaterally with 4-hole plates and screws (n = 12), or left unrepaired for control data (n = 8). CT density, molecular weight, loss of plates and screws, and preliminary bone healing were assessed at 1, 2, 4, and 6 weeks postoperatively. Histologically, no differences in bone healing were noted between control and experimental animals at any time. Three-dimensional CT reconstruction of the skull was possible without artifacts, and no significant differences (p > 0.05) were found in specific CT scan density levels across postoperative intervals. However, significant (p < 0.001) molecular weight loss of the biodegradable plates was observed through 6 weeks postoperatively, reaching approximately 50% of the preoperative molecular weight. Molecular weight loss, however, was not detectable with CT density measurements. Results demonstrated that the use of biodegradable DL-PLA plates and screws had no adverse effect on fracture healing in this model and that CT scanning and three-dimensional reconstruction were possible without artifacts, independent of material degradation and molecular weight loss. These results suggest that this DL-PLA biodegradable system may have the potential for use in craniomandibulofacial surgery when short-term rigid fixation is necessary.

Analysis of Variance↗
PubMed1993

[Carbon dioxide as an irrigation medium for percutaneous angioscopy].

Since technical progress has allowed the development of small and flexible endoscopes, percutaneous, transluminal angioscopy promises to be a diagnostic and therapeutic tool. Nevertheless, the main problem is to obtain a satisfactory bloodless visual field. The saline solutions used for this purpose present problems with hypervolaemia, insufficient clearance, and decreased refraction. We investigated a CO2 application system for angioscopy that allows the reproducible injection of variable quantities of gas, pressure, and injection time. In 10 pigs undergoing angioscopy, CO2 was injected through a Swan-Ganz catheter under blockade of the distal aorta. Using a bifemoral approach, the application of gas and the blocking balloon were controlled by an automatic gas injector. The CO2 was injected through the tip of the catheter with a constant flow and a variable pressure and time. The angioscopy procedures were videotaped. With small volumes of carbon dioxide (approximately 50 cm3; 1000 mbar application pressure) a column of gas can be created which, unlike liquids, completely displaces blood from the vessels and allows for several minutes a bloodless inspection of the aorta and the side branches without blood mixture. Carbon dioxide application allows safe and successful percutaneous angioscopy under optimal conditions if the quantities of gas, pressure, and injection time are adjustable. The tested gas injection device fulfills these conditions.

Angioscopes↗
PubMed1993

[Postoperative air embolism caused by pneumatocephalus following occlusion of the posterior fossa. A rare complication indicative of a bridging vein disruption].

Many neurosurgeons prefer the sitting position for patients undergoing surgery in the posterior fossa because of the easier access and better conditions for haemostasis. Pneumatocephalus is a possible consequence of surgery in the posterior fossa with the patient in the sitting position. When this occurs air may enter the subarachnoid space, the cisternae, the ventricular system or the subdural space; it becomes more likely when any of the following is/are present: loss of CSF, a large cavity resulting from surgery, external or internal drainage of CSF, osmotic diuresis, and hyperventilation. Distances of 1-2 cm between cranium and brain may be found. The rupture of bridging veins may cause a subsequent subdural haematoma. Air embolism due to pneumatocephalus via the same vein after closure of the cranium is in this paper for the first time. Case report. A 37-year-old man with known Hippel-Lindau disease presented for posterior fossa surgery for treatment of a haemangioblastoma of the right cerebellar hemisphere. Surgery was done with the patient in a sitting position. Apart from one short episode of air embolism without haemodynamic changes no intraoperative complications occurred. After closure of the cranium and galea an unexpected and inexplicable air embolism of 10 min duration occurred again. TEE demonstrated the air looking like a string of beads in the right atrium. As complete skin had already been closure no explanation for the air embolism could be found. The patient was positioned supine, and air was no longer detectable in the right heart after 1 min. Approximately 1 h later both pupils were dilated and unreactive to light.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Rapid, non-separation electrochemiluminescent DNA hybridization assays for PCR products, using 3'-labelled oligonucleotide probes.

Described are rapid assays for the analysis of PCR products in a one step, non-separation assay based on the use of electrochemiluminescence generated from a tris-bipyridine ruthenium (II) label. The assay uses PCR incorporation of a biotinylated oligonucleotide as a primer, with the inclusion of a labelled oligonucleotide. Oligonucleotides were labelled with an N-hydroxy succinimide ester of tris-bipyridine ruthenium (II) dihexafluorophosphate (Origen-label) by modifying the 3' and 3' 5' ends of the oligonucleotide probes. The assay makes use of the inherent thermal stability and absence of polymerase activity on such probes to allow the PCR and probe hybridization to be completed automatically on the thermocycler. The assay is concluded by the addition of PCR samples to streptavidin beads on an electrochemiluminescence analyser for binding and analysis. Target genes evaluated were the HIV-1 gag gene, and cystic fibrosis delta F-508 deletion mutation. The results obtained from these assays demonstrated the detection of 10 copies of the HIV-1 gag gene, and cystic fibrosis delta F-508 mutation in 1 ng of human DNA within 15 min. This assay format allows a rapid and simple determination of specific amplified DNA sequences, reducing the contamination risks due to washes and multiple pipetting.

2,2'-Dipyridyl↗
PubMed1992

[Plain CT of venous thromboses of the leg].

In 41 patients with deep vein thrombosis which had been demonstrated by duplex sonography, non-enhanced CT was performed at various levels before phlebography was carried out. Clots judged clinically to be fresh (1-7 days) show predominantly hyperdense thrombus material (60-80 Hu). With longer histories, on the other hand, the majority of thrombi were hypodense (50 Hu or less). Non-enhanced CT provided a rough indication of the age of a thrombus and may aid in deciding whether to use fibrinolysis. Dilatation of veins was found in 80% of the hyperdense early thrombi, but also in the presence of loose and old thrombi. This phenomenon and the presence of perivascular and soft tissue oedema does not indicate the type or age of the thrombus. These findings may be expected to occur also in other vascular areas.

Dilatation, Pathologic↗
PubMed1992

[Cervical lymph node metastasis as a primary manifestation of esthesioneuroblastoma].

A 51-year-old male patient presented with right-sided swelling of the neck and a 2-year history of decreasing olfaction that had culminated in complete anosmia. CT and MRI showed a calcified ethmoid tumor and destruction of the lamina cribrosa extending into the anterior fossa and frontal lobes. Contrast material demonstrated marked enhancement on the CT and MRI. Bilateral angiography of the external and internal carotid arteries failed to show tumor vascularity typical for an esthesioneuroblastoma but rendered an olfactory meningioma unlikely. Histological findings of cervical lymph nodes removed during neck dissection showed infiltration by an esthesioneuroblastoma (Kadish C classification). Tumor calcifications in these neoplasms are generally well seen on CT and--while not specific--may suggest the diagnosis. CT and MRI are the most sensitive methods of demonstrating local tumor growth, metastasis and bone destruction.

Combined Modality Therapy↗
PubMed1992

Improved electrochemiluminescent label for DNA probe assays: rapid quantitative assays of HIV-1 polymerase chain reaction products.

We describe the characterization and utility of a new electrochemiluminescent (ECL) label for oligonucleotides, utilizing phosphoramidite chemistry. This phosphoramidite of the tris(2,2-bipyridine)ruthenium(II) complex, bis(2,2-bipyridine)(4-[4-(2-cyanoethoxy-N,N-diisopropyl-amino) phosphinoxybutyl]4'-methyl)2,2-bipyridine ruthenium(II) dihexafluorophosphate or Origen phosphoramidite, enables the direct incorporation of the label during automated DNA synthesis. Efficiency of this automated synthesis allows the direct utilization of probes without further purification. Introduction of this labeling group is reproducible, and the ECL signal recovered is not influenced by hybridization. Furthermore, neither hybridization kinetics nor hybrid stability was affected by our label. We also demonstrate the utility of these labels for the development of rapid assays with oligonucleotides direct from automated synthesis. The clinical utility of these labeled oligonucleotides is shown with assays of total nucleic acid, extracted from peripheral blood lymphocytes of patients with acquired immunodeficiency syndrome (AIDS), to detect the human immunodeficiency virus (HIV-1). The results demonstrate the ability of the assay to quantify 30-2000 copies of HIV1 gag genes and to rapidly detect (less than 45 min) HIV-1 gag genes in a nonseparation assay. The application of this assay to clinical samples demonstrates the utility of these assays for rapid and quantitative analysis.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Rapid electrochemiluminescence assays of polymerase chain reaction products.

We demonstrate the first use of an electrochemiluminescent (ECL) label, [4-(N-succimidyloxycarbonylpropyl)-4'-methyl-2,2'- bipyridine]ruthenium(II) dihexafluorophosphate (Origen label; IGEN Inc.), in DNA probe assays. This label allows rapid (less than 25 min) quantification and detection of polymerase chain reaction (PCR)-amplified products from oncogenes, viruses, and cloned genes. For the PCR, we used labeled oligonucleotide primers complementary to human papiloma virus and the Ha-ras oncogene. These samples were followed by ECL analysis or hybridization with specific, Origen-labeled oligonucleotide probes. These studies demonstrate the speed, specificity, and effectiveness of the new ECL labels, compared with 32P, for nucleic acid probe applications. We describe formats involving conventional methodologies and a new format that requires no wash step, allowing simple and rapid sample analysis. These rapid assays also reduce PCR contamination, by requiring less sample handling. Improvements in ECL detectability are currently under investigation for use in DNA probe assays without amplification.

2,2'-Dipyridyl↗
PubMed1991

Electrochemiluminescence detection for development of immunoassays and DNA probe assays for clinical diagnostics.

Electrochemiluminescence (ECL) has been developed as a highly sensitive process in which reactive species are generated from stable precursors (i.e., the ECL-active label) at the surface of an electrode. This new technology has many distinct advantages over other detection systems: no radioisotopes are used; detection limits for label are extremely low (200 fmol/L); the dynamic range for label quantification extends over six orders of magnitude; the labels are extremely stable compared with those of most other chemiluminescent systems; the labels, small molecules (approximately 1000 Da), can be used to label haptens or large molecules, and multiple labels can be coupled to proteins or oligonucleotides without affecting immunoreactivity, solubility, or ability to hybridize; because the chemiluminescence is initiated electrochemically, selectivity of bound and unbound fractions can be based on the ability of labeled species to access the electrode surface, so that both separation and nonseparation assays can be set up; and measurement is simple and rapid, requiring only a few seconds. We illustrate ECL in nonseparation immunoassays for digoxin and thyrotropin and in separation immunoassays for carcinoembryonic antigen and alpha-fetoprotein. The application of ECL for detection of polymerase chain reaction products is described and exemplified by quantifying the HIV1 gag gene.

2,2'-Dipyridyl↗