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Biomedical subjects

S Guth

Publications and source records attributed to S Guth.

At least 37 records · Page 2Linked to original sources
PubMed1998

Interventional radiology with laser in bone and joint.

Laser energy is able to ablate, coagulate, and vaporize tissues. Its transmissibility in thin optical fibers makes it an ideal tool for use in percutaneous procedures. This article describes two applications in interventional musculoskeletal radiology. In percutaneous laser disc decompression the laser source is used to vaporize a small portion of the nucleus pulposus. In interstitial laser photocoagulation of osteoid osteoma the laser energy is used to coagulate and destroy the tumor by direct heating.

Adolescent↗
PubMed1997

Pancreas specific protein disulfide isomerase, PDIp, is in transient contact with secretory proteins during late stages of translocation.

Protein disulfide isomerase (PDI) and an additional lumenal protein of dog pancreas microsomes were previously observed to be in transient contact with secretory proteins during late stages of their co- or posttranslational translocation into these mammalian microsomes. The second protein was characterized as a 57 kDa glycoprotein. Here we identified this glycoprotein as the canine equivalent of human PDIp, a protein which was recently described as a new protein disulfide isomerase which is highly expressed in human pancreas. Canine PDIp is also a very abundant protein, its concentration in pancreatic microsomes approaches the concentration of PDI and of the major microsomal molecular chaperones. Apparently, PDIp shares with PDI not just the enzymatic but also the polypeptide binding or chaperoning activity. Furthermore, we suggest that PDIp, too, can be involved in completion of cotranslational as well as posttranslational translocation of proteins into mammalian microsomes.

Amino Acid Sequence↗
PubMed1997

Benign hyperplasia in ectopic prostatic tissue: a rare cause of pelvic mass.

Four cases of a pelvic mass due to the development of benign hyperplasia within ectopic prostatic tissue are reported. They presented a hypoechoic homogeneous or heterogeneous pattern on transrectal ultrasonography and a high signal intensity on T2-weighted spin-echo sequences on MR. On CT the density was similar to that of prostatic tissue. No recent imaging findings of this rare entity have been described in the literature. Possible aetiologies are discussed. Even if it is a rare event, the correct diagnosis can be reached. It is important for radiologists to consider the presence of this lesion because of its benign nature.

Aged↗
PubMed1997

Molar masses and structure in solution of haemoglobin hyperpolymers--a common calibration of size exclusion chromatography of these artificial oxygen carriers.

We are developing artificial oxygen carriers for medical use, based on synthetic polymers--so-called hyperpolymers--obtained by cross-linking mammalian haemoglobins. One requirement with respect to the polymers is that they should not increase the oncotic pressure of blood remarkably--this can be realized by high molecular weights of the polymers with a narrow distribution. They may act as a oxygen transporting blood additive, and--in combination with a plasma expander--as a blood substitute. Another important and desired property of the artificial oxygen carrier is a low viscosity, which--first--is due to a high degree of uniformity of the polymer size (or molar mass) distribution and--second--is influenced by the so-called structure in solution of the haemoglobin hyperpolymers. In this paper former determinations of molar masses--with size exclusion chromatography (SEC)--and of the structure in solution--using viscometric measurements--of hyperpolymers of human haemoglobin, synthetized with glutaraldehyde and with bis(thioisocyanato) benzenesulfonic acid as cross-linkers, were extended to hyperpolymers of bovine and pyridoxylated porcine haemoglobin, cross-linked with glycolaldehyde. These determinations were done by applying a new iterative procedure. Within a range of error all SEC calibration curves found were the same for all hyperpolymers investigated. So-called MARK-HOUWINK or structure in solution diagrams (logarithm of intrinsic viscosity versus logarithm of molar mass) yield equal straight lines for all the haemoglobin polymers. The first derivatives of these lines are the MARK-HOUWINK exponents which has a mean value of 0.38. These results indicate that there exists a common SEC calibration line for all different polymer haemoglobins produced with comparable preparative procedures. This calibration line differ significantly from that of native globular proteins--haemoglobin hyperpolymers are less compact--so a calibration of SEC with globular proteins for the determination of molar masses of haemoglobin polymers is erroneous. Furthermore, the structure in solution of the hyperpolymers is clearly different from that of flexible, randomly coiled, linear artificial polymers: hyperpolymers are more compact. A possible explanation is that the hyperpolymers--according to a great number of functional amino groups of haemoglobin-contain many intra-polymeric cross-links, and thus are at least import branched polymers or even macromolecular networks of the constituting haemoglobin "monomers".

Animals↗
PubMed1997

[Surgical aspects of pulmonary thrombendarterectomy].

Pulmonary thromboendarterectomy is an accepted operative procedure for treatment of pulmonary hypertension due to chronic embolism. Despite its proven value this procedure has been established at very few centers worldwide. In this paper we report our actual operative concept and operative results. Between 8'89 and 4'96 127 patients were operated with use of extracorporeal circulation, deep hypothermia and circulatory arrest. After analysis of the initial high perioperative mortality (26%, 29/108) our operative and postoperative concept changed since 11'94: 1. central incision of both pulmonary arteries, 2. endarterectomy exclusively during circulatory arrest, 3. prolonged reperfusion to 37 degrees C, 4. pressure controlled ventilation, NO-inhalation, early extubation, and 5. modified vasopressor therapy. Preoperatively 12 of the 19 patients were in NYHA class III and 6 in class IV. Mean pulmonary artery pressure was 52(17) mmHg with a calculated pulmonary resistance of 1013(579) dynes.s.cm-5. Mean circulatory arrest time was 37 min (19-57 min) (bypass time 345 min, (240-430 min)). Perioperatively two patients (11%) died (multiorgan failure; rethrombosis of pulmonary artery/right heart failure), all other patients survived (89%). Perioperative complications included reversible renal failure, delirium and postcardiotomy syndrome (1/2/1). Mean pulmonary resistance was postoperatively significantly reduced (362(124) dynes.s.cm-5) (p < 0.01). Early results of pulmonary thromboendarterectomy can be improved by consequent modifications of the intra- and postoperative concept.

Adolescent↗
PubMed1997

[Thymectomy in myasthenia gravis].

Myasthenia gravis is a relatively uncommon autoimmune disorder of neuromuscular transmission. Surgical therapy plays an important role in addition to medical treatment. Follow-up results of 52 patients with thymectomy are presented. Between 1984-1996 thymectomy via median sternotomy was performed in 52 patients with myasthenia gravis (female = 28, male = 24). The score described by Ossermann and Genkins was used for classification. According to this classification, we found 12 patients in class II(I), 21 in class IIA, 17 in class IIB and 2 in class III, respectively. A thymoma was found in 19, follicular lymphoid hyperplasia in 24 and an atrophic thymus in 9 cases, respectively. There was no mortality. Severe postoperative complications consisted of bleeding and reoperation in one patient and another patient developed a sternal instability with consecutive operative refixation. Follow-up evaluation after a mean period of 36 months (min. 6 months, max. 130 months) revealed a relief of myasthenic symptoms in 37 patients. Thymectomy is effective in the treatment of myasthenia gravis with a low complication rate.

Adult↗
PubMed1997

[Aortocaval fistula. Diagnosis using spiral x-ray computed tomography with 2D and 3D reconstructions].

We report a case of arteriovenous fistula due to spontaneous rupture of an aortic aneurysm into the inferior vena cava. This is a rare complication of atheromatous aneurysm, often difficult to diagnose as the clinical presentation may be obscure. Although aortography is the reference diagnostic investigation, spiral CT acquisition with 3D and 2D reformation allowed visualization of the arteriovenous communication and provided an accurate diagnosis.

Aged↗
PubMed1994

Divinyl sulfone cross-linked hyperpolymeric human haemoglobin as an artificial oxygen carrier in anaesthetized spontaneously breathing rats.

The production of hyperpolymer haemoglobins, exhibiting sufficiently low colloid osmotic pressure and sufficiently low viscosity is possible, even in concentrations, and therewith oxygen transport capacity, high enough to supply an organism adequately with oxygen. Such hyperpolymers, when infused, are tolerated by anaesthetized rats in acute blood exchange experiments. Ex vivo determinations of plasma colloid osmotic pressure and both, plasma and whole blood kinematic viscosity during blood exchange showed, that corresponding properties found in vivo were refound within the animal. Furthermore we could show that hyperpolymers produced from desoxygenated human haemoglobin with divinyl sulfone as a crosslinker take part in tissue supply of oxygen to a substantial degree (about 50%) without and with increased inspiratory oxygen fraction, demonstrating the principal ability of hyperpolymers to transport oxygen in blood and to deliver it to tissues.

Animals↗
PubMed1994

[A respiratory microvalve for spontaneously breathing anesthetized small animals].

For the accurate functional analysis of the gas exchange in the lungs or evaluation of artificial oxygen carriers in spontaneously breathing anaesthetized small animals, we developed a new respiratory micro-valve. The body of the valve is made of aluminium, and the flaps are made of silicone rubber. The maximum flow rate in a rat measured with a pneumotachograph and the micro-valve was an average of 19.9 ml/s during inspiration, and 17.8 ml/s during expiration. The pressure measured in the tracheal tube was -0.85 during inspiration, and +0.39 cm H2O during expiration; the end-expiratory pressure in the tube was zero. In two experiments with anaesthetised rats lasting 4-5 hours, ventilation, oxygen uptake, carbon dioxide release and the respiratory exchange ratio were 638 ml/min/kg, 21.7 ml O2(STPD)/min/kg, 16.6 ml CO2(STPD)/min/kg, and 0.77, respectively. There was no significant change in any parameter during the experiment. The micro-valve increases the dead space by approximately 35%, but this is well tolerated by the rats, which compensate by increasing their tidal volume by about 10 to 15%. The major advantage of using the micro-valve in comparison with other methods is the fact that the true difference between inspiratory and mean mixed expiratory gas can be measured with great accuracy. The micro-valve can readily be adjusted for optimal use with a range of animals.

Anesthesia, General↗
PubMed1992

[Therapeutic evaluation of Mormoiron attapulgite in acute diarrheas of infants and children. A multicenter study in controlled liberal practice versus placebo in 113 patients].

A placebo-controlled multicenter study was carried out to evaluate the effectiveness and safety of Actapulgite in infants and children with acute diarrhea. One hundred and thirteen patients, with a mean age of 28 months, were enrolled by pediatricians in the office. As recommended during acute diarrhea, the dosage of Actapulgite was doubled during the first three treatment days (2 to 4 packets a day according to the patient's weight), and reduced by half thereafter. The main effectiveness criteria was passage of the first normally formed stool, which denotes normalization of intestinal transit time. The first normally formed stool was recorded after two days of treatment with Actapulgite and was followed, on the next day, by a second normal stool, denoting complete recovery. The greater effectiveness of Actapulgite as compared with the placebo was demonstrated by the fact that both the first and the second normally formed stools were passed one day earlier with the active treatment (p = 0.01 and p = 0.002, respectively). In addition, resumption of a normal diet occurred significantly earlier with Actapulgite (4.4 days) than with the placebo (5.1 days). In addition to being effective, the study drug proved remarkably well tolerated. This study is especially valuable because of its office setting and the use of exclusively clinical criteria with a strict methodology.

Acute Disease↗
PubMed1991

The distribution of transcripts of neurogenic genes in neurogenic mutants of Drosophila melanogaster.

The neurogenic genes of Drosophila melanogaster are required for correct separation of neural and epidermal progenitor cells during early embryogenesis. Results from genetic analyses indicate that the neurogenic genes are functionally related. We have studied the spatial distribution of RNA from the neurogenic genes D1, neu, and m4, m5, m7 and E(spl) [four genes of the Enhancer of split complex] in various neurogenic mutant embryos by in situ hybridization. An abnormal distribution of RNA from certain of the genes is found in neurogenic mutants, suggesting that at least some of the functional interactions inferred from genetic data take place at the transcriptional level. We discuss these results in relation to the events of early neurogenesis.

Animals↗
PubMedDate not supplied

Potential role of duplex Doppler sonography in acute renal colic.

PURPOSE: We assessed the value of renal duplex Doppler sonography in diagnosing obstruction in patients with acute renal colic. METHODS: We compared the results of renal duplex Doppler sonography with those of intravenous urography (IVU) in 65 patients presenting with symptoms of renal colic. The Doppler spectral waveforms were used to calculate the resistance index (RI). The difference between the mean RIs (delta RI) in the 2 kidneys was calculated for each patient. The sensitivity, specificity, and accuracy of delta RI for the diagnosis of obstruction were calculated with several discriminatory thresholds. RESULTS: All patients had an obstruction on IVU. When a high delta RI threshold for obstruction (delta RI > or = 0.1) was applied, the sensitivity and specificity of duplex Doppler sonography were 10% and 80%, respectively. When the delta RI threshold was decreased, the sensitivity increased but the specificity decreased, and both remained quite low. Twelve patients had a lower mean RI in the obstructed kidney than in the normal contralateral kidney. Among 14 patients without pyelocaliceal dilatation, the sensitivity of duplex Doppler sonography was 70% with a delta RI threshold of 0.03. CONCLUSIONS: Duplex Doppler sonography is not sensitive enough to diagnose obstruction in patients with acute renal colic.

Acute Disease↗
PubMedDate not supplied

Appendiceal stump abscess.

Recurrence of traditionally treated appendicitis is rarely reported but known to surgeons and is probably underestimated. We described a case, illustrated by CT, of stump abscess 2 years after laparoscopic appendectomy. Sonography and CT are helpful in detecting pericecal changes, but diagnosis is confirmed by laparotomy.

Abdominal Abscess↗
PubMedDate not supplied

Chronobiology in mental retardation research: progress and prospects.

The premise of this review is that chronobiology, the science of biologic time structure and rhythms, is important in investigations concerning the etiology, mechanisms and effects of deficient mental adaptive development. Chronobiology is also shown to have potential importance in therapeutics and rehabilitation. Most of the information available now and supporting this wide-spread relevance of chronobiology relates to circadian rhythms, but physiological and behavioral rhythms having other cycle lengths also contribute. Recent findings in seven topic areas of chronobiology are reviewed with emphasis on facts and relationships actually or potentially important for consideration in mental retardation research. These are: 1) development of sleep and EEG patterns; 2) rhythmic susceptibility to seizures; 3) adrenocortical and dependent rhythms; 4) circadian rhythms in amino acids and biogenic amines; 5) rhythmic behaviors; 6) circadian rhythms in susceptibility and responses to drugs; and 7) circadian rhythms in human perception and performance.

Adrenal Cortex↗