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Biomedical subjects

G Koch

Publications and source records attributed to G Koch.

At least 199 records · Page 11Linked to original sources
PubMed1991

Propranolol therapy alters estimation of potential cardiovascular risk derived from submaximal postinfarction exercise testing.

We studied the effect of propranolol administration on risk assessment based on submaximal exercise testing performed early after myocardial infarction. A total of 70 patients with recent infarction underwent modified Bruce treadmill testing with simultaneous measurement of expired gases in the absence of antianginal agents including beta-antagonists. Among these, 31 patients who had at least one of the following abnormalities--ST depression greater than or equal to 1 mm (22 patients), chest pain (four patients), or treadmill time less than 360 seconds (12 patients)--were studied in a randomized double-blind fashion and received either placebo or 240 mg of propranolol/day. A total of 28 patients completed the randomized phase and were able to undergo repeat exercise testing an average of 3.4 +/- 1.8 days later. Randomized groups were equivalent at baseline except for a higher peak oxygen consumption and carbon dioxide production (p less than 0.05) in the propranolol compared with the placebo group; these differences were taken into account in statistical analyses of the study data. Resting heart rate (59 +/- 1.2 versus 82 +/- 4.2 beats/min) and peak heart rate x systolic blood pressure (14,208 +/- 496 versus 20,075 +/- 1,062) were both significantly less (p less than 0.01) after propranolol than after placebo. Eight of nine patients treated with placebo maintained ST depression greater than or equal to 1 mm from the initial to the randomized exercise test, compared with only 4 of 13 receiving propranolol (p less than 0.01). In those with continued ST depression, time to positivity was significantly longer in those receiving propranolol compared with those taking placebo (538 +/- 73 versus 318 +/- 44 seconds, p less than 0.05). In contrast, the peak ratio between carbon dioxide production and oxygen consumption was higher in those receiving propranolol compared with those receiving placebo (0.93 +/- 0.04 versus 0.81 +/- 0.03, p less than 0.05). We conclude that propranolol therapy reduces evidence of ischemia and changes traditional estimates of potential cardiac risk derived from submaximal postinfarction exercise testing.

Cardiovascular Diseases↗
PubMed1991

Influence of calcium administration on the short-term hemodynamic and anti-ischemic effects of nifedipine.

This prospective study investigated whether pretreatment with intravenously administered calcium would influence the effect of nifedipine on rest hemodynamics and treadmill performance in patients with ischemic heart disease. Seventeen patients were studied after undergoing a qualifying treadmill exercise test that revealed ST segment depression indicative of ischemic heart disease. Study subjects performed three additional treadmill tests as part of the protocol. One treadmill test was obtained from each patient to provide baseline measurements without a preceding intravenous infusion and in the absence of all antianginal drugs including nifedipine; two additional exercise tests were preceded by an infusion and 10 mg of bite-and-swallow nifedipine. The infusions, administered in a randomized, double-blind, crossover fashion, consisted of either 10 ml of 10% calcium chloride (13.6 mEq) in 50 ml of 5% dextrose in water or 5% dextrose in water alone. Rest systolic blood pressure (134 +/- 4.6 mm Hg) was unchanged after placebo infusion (135 +/- 4.6 mm Hg) but decreased to 124 +/- 4.1 mm Hg (p less than 0.01) 25 min after nifedipine administration. Rest systolic blood pressure increased after calcium infusion (from 139 +/- 4.3 to 148 +/- 4.8 mm Hg, p less than 0.01) and then decreased significantly 25 min after nifedipine administration to 135 +/- 4.2 mm Hg (p less than 0.01). Despite a decrease at the time of peak nifedipine effect after either infusion, systolic blood pressure was significantly lower after administration of nifedipine alone than after administration of calcium and nifedipine (124 +/- 4.1 vs. 135 +/- 4.2 mm Hg, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1991

Identification of false positive exercise tests with use of electrocardiographic criteria: a possible role for atrial repolarization waves.

Atrial repolarization waves are opposite in direction to P waves, may have a magnitude of 100 to 200 mu V and may extend into the ST segment and T wave. It was postulated that exaggerated atrial repolarization waves during exercise could produce ST segment depression mimicking myocardial ischemia. The P waves, PR segments and ST segments were studied in leads II, III, aVF and V4 to V6 in 69 patients whose exercise electrocardiogram (ECG) suggested ischemia (100 mu V horizontal or 150 mu V upsloping ST depression 80 ms after the J point). All had a normal ECG at rest. The exercise test in 25 patients (52% male, mean age 53 years) was deemed false positive because of normal coronary arteriograms and left ventricular function (5 patients) or normal stress single photon emission computed tomographic thallium or gated blood pool scans (16 patients), or both (4 patients). Forty-four patients with a similar age and gender distribution, anginal chest pain and at least one coronary stenosis greater than or equal to 80% served as a true positive control group. The false positive group was characterized by 1) markedly downsloping PR segments at peak exercise, 2) longer exercise time and more rapid peak exercise heart rate than those of the true positive group, and 3) absence of exercise-induced chest pain. The false positive group also displayed significantly greater absolute P wave amplitudes at peak exercise and greater augmentation of P wave amplitude by exercise in all six ECG leads than were observed in the true positive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function↗
PubMed1991

Long-term results of migraine prophylaxis with flunarizine and beta-blockers.

We followed-up 64 migraine patients after discontinuation of successful interval prophylaxis with flunarizine, propranolol or metoprolol, to investigate how long the therapeutic success would last, if further prophylaxis would be successful again, and what factors would influence the prognosis. We found that 16 out of 64 patients experienced a lasting reduction of migraine frequency, whereas 48 patients did improve initially, but later experienced a relapse. Further prophylaxis was effective in 29, poorly effective in 11, and ineffective in 8 of these patients; in 7 of the 8 non-responders prophylaxis was not changed. Negative prognostic factors were frequent attacks, a history of analgesic abuse and/or analgesic withdrawal therapy and ineffective previous prophylaxis. In conclusion, the therapeutic success decreases dramatically in the majority of patients several months after discontinuation of prophylaxis; further prophylaxis is more effective if the substance class is changed; increased analgesic intake is the most important prognostic factor. As a strategy for migraine prophylaxis we propose sequential changing of interval prophylaxis or--in patients with negative prognostic factors--long-term prophylaxis.

Adult↗
PubMed1991

Congenital giant arteriovenous malformation in a 31-year-old male.

In this case presentation we report the history of a 31-year-old male suffering from a congenital giant arteriovenous malformation (AVM) of the neck and the right chest wall over the course of 12 years. This vascular tumor was fed by dilated arteries, branches of the right external carotid, and both subclavian arteries. The first therapeutic procedure was an isolated ligation of the draining arteries, which was not successful as angiography showed two years later. As the patient rejected any further therapy, the enormous growing tumor was again treated 9 years later. At this time an interdisciplinary management involving radiologists and surgeons was arranged. Superselective embolization preceding surgical radical tumor resection was performed. After a follow-up period of almost 1 year no further signs of progression were seen, except the postsurgical embolization of one collateral external carotid branch and a beginning skin necrosis which was to be expected. However, recently progression has become evident, but the patient has refused further treatment.

Adult↗
PubMed1991

Application of a CCD linear array camera in the quantification of tissue staining: NBT detection in ischaemic myocardium.

A method was developed to quantify the intensity of tissue staining using a CCD (charge-coupled device) camera. Reflection spectra of NBT-stained (nitro-blue tetrazolium-stained) and unstained myocardium were recorded via fibre optics coupled to a CCD camera, connected to a microcomputer. The calculation of the intensity of staining was based on evaluation of the NBT-related changes of the reflectance spectrum. In each of six anaesthetized sheep, global ischaemia was induced by cross-clamping of the aorta. The hearts were removed and incubated at 35 degrees C. At predetermined times two sections of ventricular myocardium were taken, one of which was then stained with NBT, the other being left unstained. Evaluation of the reflectance spectra from stained sections during the first phase of ischaemia showed a slight loss of NBT colour intensity followed by a more rapid loss of staining until the values of the unstained sections were reached. In contrast to the conventional visual evaluation, the method provides quantitative data on the intensity of staining, and allows use of the NBT technique for statistical evaluation of what happens over time, and the regional distribution of ischaemic injury of tissue. This method may also be applied to other staining techniques.

Animals↗
PubMed1991

Acute effects of combined alpha/beta-adrenoceptor blockade v combined beta-receptor and slow channel calcium blockade in ischemic heart disease complicated by hypertension. Hemodynamic and adrenergic responses.

The effects of combined alpha/beta adrenoceptor blockade and of beta-receptor/slow channel calcium blockade on systemic and pulmonary hemodynamics and on adrenergic activity were compared in two matched groups of men suffering from ischemic heart disease and grade 1 to 2 hypertension. They were studied at rest supine and during ischemia-inducing exercise in the seated posture using invasive percutaneous techniques. Sixteen patients received 200 mg labetalol as a single oral doses, 15 received 100 mg metoprolol plus 10 mg nifedipine. Both regimens reduced pressures in the systemic and pulmonary circulation under all conditions. At rest, stroke volume and cardiac output slightly decreased after labetalol and increased after metoprolol/nifedipine. During exercise the changes induced by the two regimens were virtually identical; heart rates and vascular resistances were reduced, stroke volume increased, cardiac output was not significantly changed. Plasma renin activity was lowered by labetalol, unchanged by metoprolol/nifedipine. Plasma adrenaline increased after metoprolol/nifedipine only, noradrenaline with both regimens. Both combinations significantly lowered stroke work and the rate pressure product and had similar beneficial effects on the onset and the duration of angina. It is concluded that both combinations significantly reduce blood pressures and attenuate or offset the potential adverse hemodynamic effects of beta-receptor blockade alone without loss but rather enhancement of antianginal efficacy.

Adrenergic alpha-Antagonists↗
PubMed1991

Characterization of cloned chicken anemia virus DNA that contains all elements for the infectious replication cycle.

Circular double-stranded replication intermediates were identified in low-molecular-weight DNA of cells of the avian leukemia virus-induced lymphoblastoid cell line 1104-X-5 infected with chicken anemia virus (CAV). To characterize the genome of CAV, we cloned linearized CAV DNA into the vector pIC20H. Transfection of the circularized cloned insert into chicken cell lines caused a cytopathogenic effect, which was arrested when a chicken serum with neutralizing antibodies directed against CAV was added. Chickens inoculated at 1 day of age with CAV collected from cell lines transfected with cloned CAV DNA developed clinical signs of CAV. The 2,319-bp cloned CAV DNA contained all the genetic information needed for the complete replication cycle of CAV. The CAV DNA sequence has three partially overlapping major reading frames coding for putative peptides of 51.6, 24.0, and 13.6 kDa. The CAV genome probably contains only one promoter region and only one poly(A) addition signal. Southern blot analysis using oligomers derived from the CAV DNA sequence showed that infected cells contained double- and single-stranded CAV DNAs, whereas purified virus contained only the minus strand. It is the first time that the genome of one of the three known single-stranded circular DNA viruses has been completely analyzed.

Amino Acid Sequence↗
PubMed1991

Opioids in the milk.

In various studies, the milk has been screened for the presence of free or precursor-bound opioids. In fact, various opioid receptor ligands with agonistic or even antagonistic activity were found. Besides the alkaloid morphine, peptides derived from alpha-casein (alpha-casein exorphins), beta-casein (beta-casomorphins; beta-casorphin), alpha-lactalbumin (alpha-lactorphins) and beta-lactoglobulin (beta-lactorphin) were among the agonists. In addition, certain peptides derived from k-casein (casoxins) or from lactoferrin (lactoferroxins) were found to behave like opioid antagonists. Although a functional role in the mammalian organism for all of these compounds appears to be well possible, evidence has only been presented for the functional significance of beta-casomorphins, so far. These peptides might play a role in reproduction or nutrition in the female, in the newborn's or in a milk consumer's organism, respectively. Thus, opioids related to milk might represent essential exogenous extensions of the endogenous opiodergic systems.

Amino Acid Sequence↗
PubMed1991

Fluoride release from glass ionomer cement in vivo and in vitro.

The aims of this study were to investigate in vivo the release of fluoride from three glass ionomer cements (GICs) Vitrebond, Ketac-Fil and ChemFil II into the saliva of preschool children for a 1-year period and also to study in vitro the release-absorption-release of fluoride from the same GICs for 16 weeks. In the first part of the study, glass ionomer restorations were placed in primary teeth in preschool children. Unstimulated saliva was collected and the fluoride in the saliva was measured before placement of the restorations, immediately after, after 3 weeks, after 6 weeks, and after 1 year. In the second part of the study, test specimens of GICs were placed in deionized water and the release of fluoride was measured weekly for 16 weeks. At week 12, samples were exposed to fluoride toothpaste. The concentration of fluoride in saliva was 0.04 ppm before placement of the restorations. After three weeks it had increased to 0.8 ppm and the level remained as high as 0.3 ppm even after 1 year. In the laboratory study the tested glass ionomer cements showed a capacity to absorb fluoride from the fluoride toothpaste and then release it. It is concluded that glass ionomer cement can act as a rechargeable slow release fluoride device.

Child↗
PubMed1991

Osseointegrated implants in the oral habilitation of a boy with ectodermal dysplasia: a case report.

The most characteristic oral feature in ectodermal dysplasia is hypodontia. Children and adolescents suffering from ectodermal dysplasia often need extensive and complicated prosthetic treatment. The development of techniques for osseointegrated implants offers new possibilities for the oral habilitation of these children. This paper describes the oral habilitation of a boy with severe ectodermal dysplasia and where Brånemark osseointegrated implants have been used as part of the treatment. The patient was seen at the dental department at the age of 1.5 years. Two conically-shaped upper incisors were at that time the only teeth that had erupted. The treatment was planned in a multidisciplinary odontological group involving paediatric dentistry, orthodontics, prosthodontics, oral surgery and maxillofacial radiology. At the age of 3 years it was verified that the boy had four primary teeth (53, 51, 61, 63) and four permanent teeth (16, 11, 21, 26). There were no teeth in the lower jaw. The alveolar ridges in the edentulous areas were low or missing. During the period 3-6 years of age the boy used an upper partial denture adapted to allow the mesial drift of the 16 and 26 teeth. At the age of 6 years, two Brånemark implants were inserted in the lower front-cuspid region. A specially designed overdenture for the lower jaw was constructed. The overdenture was retained in contact with the male attachments by two cuffs of heat-polymerized resilient silicone. Over the next 4 years the dentures were modified due to the eruption of permanent teeth and growth. However, only minor corrections were necessary concerning the retention system of the lower denture. The implants are well osseointegrated and stable and allow the boy to use a lower denture without any complications.

Anodontia↗
PubMed1991

[Experimental animal studies for the detection of circulating Toxoplasma antigens].

Rabbits and mice were infected by Toxoplasma gondii (RH and HanR) and Hammondia hammondi. An enzyme immunoassay with monoclonal antibodies was used to reveal circulating Toxoplasma antigens. They were found only in mice and rabbits that had been infected by the cyst-forming strain Toxoplasma HanR. In mice infected by Hammondia hammondi low antibodies titres were found that showed a cross-reaction with Toxoplasma. The enzyme immunoassay for evidence of Toxoplasma antigens demonstrated a negative reaction in these animals.

Animals↗
PubMed1991

Dental caries in one- and two-year-old children living in Sweden. Part I--A longitudinal study.

There are few epidemiological studies on caries prevalence in young children. The aim of this study was to describe the caries prevalence in 1- and 2-year-old children. All 1-year-old children, living within the area of four child welfare centres, were invited to participate. 632 children out of 671 invited were examined for dental caries. Among the children examined 120 (19%) were immigrants. One year later 326 of the 632 previous examined children were selected for a second examination of dental caries. Fifty-four children (18.1%) were immigrants. At the age of one and two years 0.5 and 7.7 per cent respectively of the children had caries. In 2-year-old children with caries the mean number of decayed tooth surfaces was 6.3. About fifty-two per cent of this group of children were immigrants. In 2-year-old immigrants 22.2 per cent had caries compared to 4.5 per cent in non-immigrant children (p less than 0.001). This study shows that, as early as at one and two year of age, a group of children have developed a number of carious lesions. Further studies in infants on predisposing factors related to early caries activity are urgent in order to find measures for effective preventive care.

Child, Preschool↗
PubMed1991

Craniomandibular function in juvenile chronic arthritis. A clinical and radiographic study.

Craniomandibular function was studied in 70 subjects with juvenile chronic arthritis (JCA). The subjects represented the total group of children and adolescents with the diagnosis JCA in a Swedish county. At examination, the median age of the subjects was 11.9 years and the median duration of the disease was 2.6 years. The most important finding of the study was the high prevalence (41%) of radiographic signs of temporomandibular joint (TMJ) pathology. Few subjects showed the typical craniofacial abnormalities associated with JCA, like mandibular micrognathia, facial asymmetries and open bite. Subjective symptoms of dysfunction were almost absent in subjects younger than seven years but were reported by 56% of the older subjects. TMJ sounds and pain on jaw movements were the most frequent symptoms reported. At the clinical examination, TMJ crepitations and restricted horizontal jaw movements were noted in 26% and 32% respectively. The high prevalence of TMJ involvement found in this study underlines the importance that dentists become part of the medical team responsible for the treatment of children and adolescents with JCA.

Adolescent↗