Biomedical subjects
Publications and source records attributed to H Lenz.
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In vitro experiments on perforating and cutting 14 human nasoantral walls using an argon laser are described. The drilling velocity is proportional to the power density up to 100 W/mm2. The cutting velocity is measured using focussed spots of 40 micrometer diameter and powers from 5 to 40 W. Histological studies were performed at the edges of the lesion. The experiments show that the technical problem for producing a window in the nasoantral wall using a laser can be solved.
Graphs and tables are shown describing the growth especially the depth of the ice-ball in tissue during freezing with round flow and massive probes (2-20 mm diameter). Thus prior to clinical application of cryosurgery the probe diameter and the time of freezing can be estimated corresponding to the size of the tumor. Results are presented for temperatures of the cooling fluid of -196 degrees C (liquid nitrogen) and -80 degrees C.
Intravasal temperature measurements during cryosurgery on the A. carotis and V. jugularis of the rabbit are described. Different flow conditions and freezing systems are investigated. The measurements are compared with histological findings. Theoretical investigations about the freezing process give information about the physical condition of a total freezing of the vessels.
First clinical experiences in the treatment of vasomotr rhinitis of 3 patients using an Ar+-laser are discussed. Punctiform and stripe laser lesions were produced on the lower human turbinates. Macroscopically the typical laser lesion consists of a central area of carbonisation surrounded by a sharply bordered zone of coagulation. Later a hyperemic margin arises. Some days after laser application an ulcus developes which is cleaned after some days. 20 days after laser application the wound is healed completely. The advantage of laser surgery is the absent of blood and pain if premedication and surface anesthesia are used. Laser surgery is compared with present-day surgical techniques for treatment of vasomotor rhinitis. Within the present time of observation of 6 months the patients are free of symptoms, if a sufficient laser surgical treatment took place. The laser surgical technique and the contruction of the laser beam guide system is described. At a laser power of 1.5-2 W and a beam diameter of 0.7 mm on the tissue the time of irradiation was several seconds on each lesion. The disadvantages of the laser technique are the high costs for the laser instrument and some technical problems with the nasal end tube.
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The clinical features and genetic inheritance of cerebellar ataxia, presumably of the Holmer type, are described in a family with four affected members over three generations. Two of these cases were severly affected, whilst the remaining two cases were probably of a relatively mild form. The pitfalls in diagnosis are discussed and the dangers of incorrect diagnosis pointed out.
1. Oxalacetase from Asperigillus niger was found to be an inducible enzyme, the induction being dependent not only on neutralisation of the acidic growth medium but also on the presence of carbonate. An explanation is proposed. 2. Three methods were established for the quantitative determination of oxalacetase activity. These are based on the determination of the product acetate, on the absorbance of oxaloacetate and on coupling the hydrolysis of oxaloacetate to the oxidation of malate by NAD in the presence of malate dehydrogenase. 3. Oxalacetase was purified about 50-fold from cell-free extracts of A. niger and used to determine some of its properties such as kinetic constants. 4. 2S-[U-14C, 3-2H2] Malate in the presence of oxalacetase, NAD and malate dehydrogenase was partially converted to acetate and oxalate. The 3H/14C ratio of the isolated acetate was nearly twice as high as that of the malate used initially. The result demonstrates that the keto form of oxaloacetate, not the enol, is the substrate of the enzyme. 5. Equimolecular mixtures of 2S, 3S-[3-2H1] malate + 2S-[2-2H1] malate (mixture 1) and 2S, 3R-[3-2H1, 3H1] malate + 2S, 3R-[2-2H1, 3-3H1] malate (mixture 2) were prepared from 2S-[3-3H2] malate by incubation with fumarase in normal and tritiated water, respectively. The isolated mixture 1, in the presence of oxalacetase, NAD and malate dehydrogenase was incubated in tritiated water for formation of acetate and oxalate; the isolated mixture 2 was treated likewise in normal water. 6. The mixtures of symmetrically labelled [3H1] acetate and chiral acetates thus produced were isolated and the configuration of the [3H1, 3H1] acetate specimens was determined in the sequence acetate leads to malate leads to fumarate, as usual. The [2H1, 3H1] acetate derived from 2S, 3S-[3-2H1] malate (present in mixture 1( yielded a malate which on incubation with fumarase retained 65.0% of its total tritium content. This chiral acetate, therefore, had the R configuration. The [2H1, 3H1] acetate derived from 2S, 3R-[2-2H1, 3-3H1] malate produced a malate which retained 35% of its total tritium content, and therefore had the S configuration. 7. It was concluded that the detachment of the oxaloyl residue from oxaloacetate and its replacement by a proton proceed with inversion of configuration at the methylene group which becomes methyl during the hydrolysis.
1. R-Acetate was generated enzymically from R-acetate in the sequence acetate leads to malate leads to oxaloacetate leads to acetate, and S-acetate likewise from S-acetate. It was concluded that the formation of malate on malate synthase involves the operation of a normal isotopic effect combined with inversion of configuration. The malate synthase kH/k2H was determined as 3.7 +/- 0.5 by a method which yields results independently of the stereochemical purity of the chiral acetates used initially. 2. R-Acetate was also generated from R-acetate in the sequence acetate leads to citrate leads to malate leads to oxaloacetate leads to acetate, and S-acetate likewise from S-acetate. The conclusion is the same as given above, but refers to the formation of citrate on the re-synthase. 3. 2S,3R-[2-2H1,3-2H1,3H1]Malate and 2S,3S-[2-2H1,3-2H1]malate were prepared from 2S-[2,3-2H3]malate by treatment with fumarase in tritiated water and normal water, respectively. It was assumed that these malate specimens were pure with respect to chirality as generated by isotopic labelling. 4. These two malate specimens were partially converted (about 9%) to acetates in conditions where no racemization at the level of transiently formed oxaloacetate occurred. That no racemization took place was demonstrated experimentally. Oxidative enzymic hydrolysis of 2S,3R-[2-2H1,3-2H1,3H1]malate in normal water and of 2S,3S-[2-2H1,3-2H1]malate in tritiated water produced S-[2H1,3H1]acetate and R-[2H1,3H1]acetate, respectively. 5. The isolated R-[2H1,3H1]acetate and S-[2H1,3H1]acetate on configurational analysis yielded malates which in the presence of fumarase retained 79.7 +/- 0.7% and 20.3 +/- 0.9%, respectively, of their total tritium content. The symmetric deviation from the 50% value found with [3H1]acetate strengthens the conclusion that stereochemically pure chiral acetates were analyzed. The malate synthase kH/k2H was determined from the data of this study as 3.9 +/- 0.2. 6. The average of the values given under paragraphs 1 and 5 for the isotopic discrimination on malate synthase corresponds to kH/k2H=3.8 +/- 0.1. It was concluded that the configurational analysis of stereochemically pure R-[2H1,3H1]acetate and S-[2H1,3H1]acetate yields malates which in the presence of fumarase retain 79 +/- 2% and 21 +/- 2%, respectively, of their total tritium content. Hence, a deviation of 29 +/- 2% from the 50% value represents the actual amplitude of the configurational assay. 7. Outlines are given for an enzymic generation of chiral acetates in preparative scale.
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The efficiency and informative values of long-term infusion-cholegraphy was examined in 30 patients with hepatic elimination dysfunction or previous negative intravenous cholangiocholecystography. It could be shown that a diagnostically useful demonstration of the biliary tract could be obtained in 29 out of 30 cases by increasing bilirubin up to 3 mg% and by infusing contrast medium for 3 hours. In spite of the increase in iodine content, the infusion of contrast medium was better tolerated than the intravenous application of contrast medium. Hepatic toxicity could not be established.
In the paper biological mechanisms of laser radiation on tissue are summerized. The specific features of different types of lasers are considered, e.g. wavelength. Focussing problems to rise the power density are described. The advantages and disadvantages of laser surgery are discussed. It is shown that the laser is well suited for an otolaryngological microsurgery. The present applications in otolgaryngology consist of about 25 papers which are evaluated and concentrated. Later surgery of the larynx is of special interest. Many clinical applications have been performed. Further experimental work exists in the region of the oral and nasal cavities, of the face and the neck. Some basic research without clinical application has been performed on the cochlea and the semicircular canals. The advantages of laser surgery are e.g. lack of blood, high precision, good healing of the wound.
The macroscopical and lightmicroscopical findings at the mucosa of the hamster cheek pouch after irradiation with an Argon-Ionlaser (wave-length 0.488 mum, power 200 mW, beam diameter 0.5 mm, power density 100 W/cm2) are described immediately, 1; 2,5; 5 and 10 days after irradiation. The mucosa was exposed 10 sec, 30 sec, 1, 2, 5 and 10 min to the radiation. With growing laser dosis the lesions of the mucosa and the postoperative healing time increases.A clinically useful optimal mucosa lesion with a short healing duration (within 5-10 days) is obtained only by application of a low and a middle laser dosis. There are two kinds of mucosa destruction by laser: 1. The destruction can be producing a coagulation necrosis with subsequent unbloody sloughing, resulting in an ulcus with rapid healing by complete reepithelisation and a small amount of connective tissue. 2. An immediate destruction is obtained by carbonisation of tissue after application of a middle to high laser dosis resulting in an ulcus with slow healing and also complete reepithelisation and small connective tissue. The typical laser lesion consists of 3 zones: The carbonisation zone is surrounded by a small coagulation zone followed by a zone of granulation tissue including thrombs and necrosis of the vessel walls. The unbloody procedure is based on an occlusion of the vessels immediately during laser radiation and later on by thrombosis in the periphery of the lesions. The possible clinical applications are discussed.
The microstructural surface of non cornified squamous cell carcinomas of human vocal cords are described scanning-electron-microscopically. Numerous bud-like cytoplasmic protuberances like microvilli, mostly close together are found, so that a considerable enlargement of the cell-surface results. For this reason a possible metabolism with resorptive function on the surface of non cornified squamous cell carcinomas might be drawn scanning-electron-microscopically. The surface of normal squamous cells of human vocal cords show microplicae mostly parallel arranged to each other. In the margin of non cornified squamous cell carcinomas there are as well bud-like cytoplasmic protuberances like microvilli as microplicae.
The light microscopic findings of tonsillar tissues from nineteen patients (aged 13-51) with the clinical diagnosis of chronic tonsillitis are described at sequential intervals following cryosurgical treatment. The Cooper instrument was used, containing liquid nitrogen and capacity limited cryoprobes as well as probes of a flow system. Two consecutive freeze-thaw cycles were used during a single session in each patient, with freezing time varied from 30 seconds to three minutes. In addition to primary cryosurgical tissue changes such as hyperemia, edema, inflammation, necrosis, fibroplasia with capillary increase, collagenous fibrosis and reepithelialisation, the following could be found: 1. A different cryosensibility of the cells and fibers within the cryolesion: The tonsillar septae are much more resistant to cold than the lymphoid tissue. Of this latter tissue, the reticulin cells and the lymphoblasts are more sensitive to the cold changes than are the matured lymphocytes. In the epithelium the stratum basale is as sensitive to cold as the lymphoreticulum. The outer epithelial cells are more resistant to cold than the basal cells. 2. A quick proliferation in the periphery of the cryolesion is seen in the form of an acanthosis and papillomatosis which begins before slough of necrotic debris occurs. 3. Sharp demarcation and protracted sloughing of necrotic epithelium from the free tonsillar surface or crypts and lymphoid tissue can be seen. 4. Reepithelialization can first be seen following slough of the cryonecrosis twenty days following cryosurgery, after which total reepithelialization occurs.