Biomedical subjects
Publications and source records attributed to A Koch.
A total of 60 eyes with retinoblastoma were examined by echography using the A-scan (Kretz 7200 MA) and B-scan (Ocuscan 400) at different sensitivity levels. The results documented by polaroid photographs were analysed quantitatively. Some additional diagnostic criteria were obtained. The differential diagnosis of a broad spectrum of vitreoretinal diseases is discussed.
Cardiomyotomy and fundoplication were performed in 7 children with achalasia of the oesophagus. They were followed up clinically, radiologically and manometrically from 7 to 18 years. Virtually all clinical symptoms and complaints disappeared immediately postoperatively and the patients remained free from symptoms well into adolescence except for very mild intermittent dysphagia in two of them. The residual mega-oesophagus and the disturbances of motility were least apparent in those operated on in early infancy. It may, therefore, be assumed that the motility pattern is more likely to return to normal in the oesophagus of the infant due to the relatively short period of dilatation. Fundoplication after Nissen did not alter the existing motility but was able to prevent gastro-oesophageal reflux and its possible grave consequences in all cases.
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The interaction of endonuclease Hinf I with single-stranded fd DNA was examined. The sizes of the cleavage products indicate that the enzyme cuts this substrate at the same sequences as double-stranded DNA (GANTC). To determine whether or not the recognition sites in single-stranded DNA have to be present in double-stranded form in order to be cleaved, DNA fragments containing complementary or non-complementary Hinf I sequences were prepared and treated as substrates. The results suggest that completely base-paired recognition sites are necessary for cleavage. Sequences surrounding the Hinf I pentanucleotides significantly modulate the reaction rates.
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Olfactory bulbectomy was performed on wild male European hamsters at different phases of their circannual body weight rhythm. Olfactory bulbectomy was always followed by an immediate hyperphagia the magnitude of which varied with the time of the year it was performed. The bulbectomy did not affect the phase of the circannual body weight rhythm, although in certain cases the rhythm is attenuated or apparently phase-shifted. Hyperphagia was delayed by food restriction but reappeared when animals were placed on ad lib food. The possible role of olfactory bulbs in the regulation of body weight, and the possibility that the maintenance expenditure of the bulbectomized animals is higher than that of the controls are discussed.
Indications for fundoplication in 70 infants with cardiac sphincter insufficiency are analysed and subdivided into absolute and relative indications in accordance with complications conditioned by reflux. Endoscopy has proved to be the most important diagnostic method for deciding whether antireflux surgery is necessary. It enables proof or exclusion of oesophagitis as the most frequent and most severe consequence of reflux. Functional tests, such as manometry and long-term measurement of pH, are important especially in cases where severity and pattern of the disease have not been clarified. Such tests enable assessment of the function of the cardia and tubular oesophagus, and hence the hazards to which the oesophagus is exposed by the reflux of the gastrointestinal contents. Hence, they represent a contribution to a reduction of the incidence rate of surgery to the absolute minimum which is a "must" at this age, without exposing the young patient to the risk of a serious complication.
Thirteen cases of urethral trauma in childhood are reported. The nature and management of such injuries are discussed. As a rule urethral ruptures are difficult to treat but long term results are surprisingly good irrespective of the initial procedure. Nevertheless, we do have the impression that with an initially aggressive operative treatment - aimed at a good anatomic reconstruction of the urethra - this goal is achieved much faster and with less complications.
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The case of an 11-year-old boy with hypermetropia of +22.0 diopters is reported. Axial length was only 14.8 mm. The features and extreme rarity of this variation in the shape of the globe is outlined. The dimensions of the eyeball were measured by echography and compared to the emmetropic eye of the adult. Only vitreous length was found to be shortened, while the dimensions of the anterior segment were within normal limits. The term posterior microphthalmos without microcornea was chosen. Associated pseudopapilledema and choroidal folds were found. The literature is reviewed.
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A method was developed to determine the way the growth of active protein depends both on age and plane of nutrition. The method assumes that active protein grows according to the relation 1-exp(t/tau) on any single plane of nutrition. Tau varies hyperbolically with the nutritional status. Parameters for the nutritional dependence are estimated from a plot of the energy available for growth as a function of 1/(tau-tau 0) where tau is the time constant for growth of active protein and tau 0 is the minimum possible time constant. This plot is forced through the origin. Once the complete dependence of tau is known, the energy available for growth can be partitioned between the production of new active protein and the deposition of lipid for any age and any plane of nutrition. The method was successfully applied to Moulton's data for the growth of steers. About 80% of the energy available for growth of active tissue is stored, either as new active protein or as lipid. This total efficiency changes little, either with age or with plane of nutrition, although the ratio between active protein and lipid production changes strikingly. The relation between the available energy and lipid production is probably concave.
A mathematical model for the programmed control of growth is developed. The growth considered is that of metabolically active tissue (MAT) and fat. The model postulates that the energy available after maintenance and activity needs have been met and after any necessary supporting tissue has been synthesized forms a common pool. Fat is synthesized from this pool with first order kinetics. The production of protein for MAT requires an intermediate called X. The kinetics of protein production are second order in which the magnitudes of the common energy pool and X are the reactants. X is formed from a precursor called Y and the total quantity of Y is fixed early in post-natal life. The model qualitatively accounts for the patterns of growth of both fat and MAT as functions both of age and of nutritional status. It also predicts both compensatory growth and a sigmoidal growth curve. Of the four rate constants in the model, one of them can be determined from data in which animals are grown on different constant planes of nutrition. Identification of the other rate constants requires data from the transient response to change in the plane of nutrition.
Early uptake curves of L-lactate and of mannitol were measured in quartered, incubated mouse diaphragms. Uptake was determined at 15, 30, and 45 s for various concentrations of lactate in the external solution as well as in the presence and absence of the competitive inhibitor of lactate transport, alpha-cyano-4-hydroxycinnimate. In normal preparations, when the external lactate concentration was 10 mM or less, the ratio of lactate-to mannitol space in the tissue was 1.7. This value was nearly independent of time and of external concentration. In normal preparations, when the external lactate concentration was greater than 10 mM, the ratio of lactate-to-mannitol space rose with time. At a fixed time, however, this ratio fell with increasing lactate concentration. In the inhibited preparations, the ratio of lactate-to-mannitol space rose with time at all concentrations. When lactate concentration was greater than 5 mM, this ratio was independent of the external concentration. The results suggest that there are two modes of lactate entry into these muscle cells. Entry can occur by means of a saturable system. When external lactate concentration is low, entry rates for this process are rapid compared with diffusional rates. This system probably saturates at concentrations near 10 mM and can facilitate transport in either direction. In addition, an appreciable passive leak is present. This leak accounts for about one fourth of the membrane transfer when external lactate is low, but is equal to the carrier transfer when lactate concentration is 30 mM. A model was developed to describe the entry of a permeating solute, such as lactate, into an isolated tissue.
With the aid of a specially designed combination electrode for infants, 20-24 hr monitoring of esophageal pH was undertaken in 15 infants, aged 5 wk-11 mo. Results demonstrated that the reflux time pH less than or equal to 4 was valid for this age group as for adults, to differentiate between physiologic and pathologic reflux. A new parameter, that of clearance time, defined as normalization time required to return to initial pH, was introduced to improve pH assessment. Both parameters showed a highly significant correlation in relation to each other, and were consistently in accord with the clinical symptoms.
The effect of cigarette smoking on the cardiovascular system was determined in the following way: Two cigarettes of relatively high (1.54 mg) and very low (0.08 mg) nicotine content were smoked and compared to sham smoking. After inhalation under standardized conditions there was a relatively high increase of the plasma nicotine levels and a subsequent exponential decrease. Two hours after smoking the levels were still elevated. After 2 low nicotine cigarettes there was a significant small short-term increase. The changes of the pulse rate were directly related to the nicotine levels and the pulse pressure transit time from the heart to the calf and the digital blood flow was indirectly related to them. The regulation of these parameters is exactly related with the nicotine levels probably through the release of catecholamines. The cardiovascular reactions after smoking may indicate the additional myocardial work load after cigarettes of different nicotine content.
The effect of somatostatin on the secretory process of the rat exocrine pancreas has been studied using a combined in vivo- in vitro system. Somatostatin in a concentration of 5 x 10(-6) g/kg/h was infused alone or in combination with low (5 x 10(-7) g/kg/h) and high (5 x 10(-6) g/kg/h) doses of synthetic caerulein. All aspects of the secretory process were then studied in vitro using isolated pancreatic lobules. Somatostatin inhibits both basal and stimulated discharge of enzymes and newly synthesized proteins thus leading to increased enzyme content. The stimulatory action of low doses of caerulein is nearly totally blocked, however, the induction of an acute non-hemorrhagic interstitial pancreatitis due to supramaximal doses of caerulein is not prevented, but only reduced in its severity. Furthermore, somatostatin infusion following the induction of pancreatitis has a beneficial effect on recovery, since increase levels of pancreatic enzymes in blood are quickly reduced and cellular infiltration of the diseased pancreas is nearly prevented.