[Use of membranes based on collagen as tissue substitutes]

Collagen, as biocompatible and bioactive non-specific polymer, occupies prominent position in the field of tissue engineering. The advanced biomaterials prefer collagen as a matrix for biodegradable implants as are biosynthetic skin substitutes, tendon and ligament substitutes, but also cartilage. Many studies notice the application of chemically modified collagen membranes for hernia and anastomoses reparations, vascular prosthetic materials, or for collagen tubes used in regeneration of peripheral nerves. Besides of defining main problems of tissue engineering, the paper analyses the developmental tendency of these biomaterials in the world, and compares it with the situation in Slovak Republic.

Biocompatibility Studies of a New Biosynthetic Dermal Substitute Based on Collagen/Hyaluronan Conjugate

The use of glycosaminoglycans (GAGs) as the second macromolecular component with collagen for the membrane preparation is based on the idea to create a biodegradable scaffold for new tissue. A hybrid collagen/hyaluronan membrane with specific bubble macrostructure was designed to serve as a synthetic dermal substitute. The objectives were to explain the two questions: what is the local biological response to the implanted membrane, and what is its reconstruction rate in tissue. The histological study proved low irritability, good compatibility, ingrowth of autologous tissue starting on day 7 post implantation, and resorption within four weeks. The major part of the implant was replaced by autologous tissue at the end of three weeks post implantation. The overall local biological response to implant was very good.

Our experience with the use of cerium sulphadiazine in the treatment of extensive burns

The development of the burn disease with infection as the most important complication represents still a major problem in burn patients. With the introduction of the method of early surgical excision of the Af1p4r with immediate grafting in major burns, improved survival has been achieved, particularly in children. However, especially in adults, early massive excisions did not prove to be of much benefit for survival. In these cases, more-or-less sequential staged excisional procedures have been introduced by many renown burn surgeons. In 1976 Monafo et al. presented the cerium nitrate-silver sulphadiazine cream (CSD) combination for topical therapy. The addition of 2.2% of the rare earth metal cerium salt to silversulphadiazine causes the formation of a relatively hard, yellow, leather-like eschar with excellent resistance to infection and good long-term adherence to the burn wound. This allows the surgeon to perform late tangential excision and immediate autografting thus decreasing the open wound size and the rate of severe infections originating in the burn wound itself. We report our experience with the treatment of 20 patients with deep burns exceeding 20% of the BSA with cerium nitrate-silver sulphadiazine cream compared with a similar group of burn patients treated by silver sulphadiazine cream alone. CSD proved to be safe and effective in the treatment of deep and extensive burns. Its advantages include easy and painless application and removal, turning the necrotic skin to yellow, and a leathery crust with good resistance to infection, thus enabling later, or staged, sequential excisions in cases where early massive excisions are not possible.

The use of growth hormone in the treatment of extensive burns: a case report

Growth hormone is an anabolic hormone that causes increased cell growth, positive nitrogen and calcium balance, lipolysis, hyperglycemia, and promotes protein synthesis. Its beneficial effect in burn treatment was proven particularly in children, by Herndon's group. The authors report The case of a 12-year-old boy with an electrical arc burn of 81% of the BSA, 60% of the BSA being full thickness loss. Recombinant human growth hormone (Norditropin, Novo Nordisk) was administered at daily doses of 0.52 i.u./kg starting on day 19 post-burn for 15 consecutive days. The treatment was well tolerated except for mild insulinoresistance, which could be easily corrected by slightly increasing the insulin added to glucose solutions. After 56 days of intensive care treatment and several excision and grafting procedures, the majority of burns were healed.

Detection of melanoma metastases with thallium-201 scintigraphy

Thallium-201 accumulates well in various malignant tumors. The aim of this study was to evaluate the potential of 201Tl imaging in patients with metastatic melanoma.

METHODS

Fifty patients with suspected melanoma metastases were studied after intravenous injection of a mean tracer activity of 100 MBq 201Tl-chloride. We took sequence images up to 5 min (15 sec/image) and immediate whole-body images with a double-headed camera and a high-resolution collimator.

RESULTS

Of 36 patients with metastatic melanoma confirmed by histopathology, metastases were detected in 28 patients using 201Tl imaging. The tumor-to-background ratio ranged from 2.0 to 4.5 (mean 3.2). There were 8 patients with false-negative findings (sensitivity = 78%). Five false-negative findings were lymph nodes greater than 1.5 cm with tumor-to-background ratios lower than 1.5. Only a few cutaneous metastases smaller than 1 cm could be detected. There was one false-positive finding of an inflamed lymph node. The optimum time for imaging was 2-5 min postinjection.

CONCLUSION

These data suggest that 201Tl imaging is an accurate method for the detection of melanoma metastases. The short waiting period after injection, the lack of side effects and the sensitivity of about 80% may qualify this method as a routine investigation in patients with high-risk melanoma.

Recurrent liver failure with severe rhabdomyolysis after liver transplantation for carbon tetrachloride intoxication

Acute liver failure due to intoxication is a rare indication for liver transplantation which a usually has a good prognosis. We herein report the case of a young male, who underwent orthotopic liver transplantation for acute liver failure due to carbon tetrachloride intoxication. Apart from hepatic and renal failure, the patient also developed severe rhabdomyolysis, which has not thus far been described as a toxic effect of this chemical agent. Despite forced hyperventilation, which is known to be the most effective means of eliminating the specifically lipophylic agent, as well as excessive plasma exchange following intravenous administration of fat emulsions, liver failure recurred when blood carbon tetrachloride concentrations were already at non-toxic levels. Retransplantation of the liver together with a kidney was only temporarily successful, since the patient died due to aspergillus sepsis. Based on this experience, we would recommend that whenever possible in patients with carbon tetrachloride intoxication, liver transplant should be delayed until most of the toxic agent has been eliminated in order to prevent fatal graft damage.

[Selective regional lymphadenectomy in malignant melanoma using a gamma probe]

The accurate excision of the first tumour draining lymph node (sentinel lymph node SLN) can prevent extended surgery intervention in many patients with malignant melanoma. The aim of our study was to test the practicability of the SLN dissection using a gamma probe. In a total of 52 patients, mostly with high-risk melanoma, a selective lymph node dissection was performed. We injected intracutuneously about 50 MBq Tc-99m colloid around the tumour or scar followed by dynamic and late static imaging. The site of SLN was localized with a gamma probe and marked on the skin. This was followed by the dissection of the SLN using the gamma probe. In 51 of 52 patients the SLN could be found intraoperatively using the gamma probe. The SLN contained microscopic metastases in 13 patients (24%). The rate of positive SLN was 40% in patients with high-risk melanoma (Breslow thickness more than 1.5 mm). In case of positive SLN a second surgical intervention with radical lymph node dissection was followed. We conclude that dynamic lymphscintigraphy and the selective lymph node dissection using the gamma probe is a simple and minimally invasive method which can improve the survival probability in patients with micrometastases.

Fluid resuscitation in thermally injured pediatric patients

More than two-thirds of critical burns in special burn units are children. The burned child continues to represent a special challenge, since resuscitation therapy must be more precise than that for an adult with a similar burn. Children have a limited physiologic reserve and the pediatric fluid replacement therapy is based on the principle of separate calculation of physiological and pathological losses. We have reviewed the most widely accepted pediatric isotonic fluid protocols. All these protocols calculate for replacement of pathological losses with a need of 2 ml/kg/% BSAB (body surface area burn) or 4 ml/kg/% BSAB. We choosed the formulas of two Shriner's Burns Institutes--the Cincinnati and the Galveston Unit as representatives, and calculated the fluid therapy for model burn children weights of 10 kg, 30 kg with 20, 40, 60, 80% BSAB. The results of calculations where compared with physiologic parameters of children. In conclusions we could show, that the 4 ml/kg/% BSAB formulas do replace all theoretically predicted pathophysiologic losses due to burns. However, the 2 ml/kg/% BSAB formulas are more practical as a guideline for resuscitation of pediatric patients because of greater therapeutical range and better clinical response of children threatened by burn shock. It is important to remember that all formulas are only guides to fluid therapy, they should be modified according to individual needs and clinical status of the patient. Only successful restoring and maintaining perfusion pressures leads to optimal oxygenation of injured and noninjured tissues, which promotes spontaneous healing, prevents wound conversion, minimise bacterial colonisation, and prepares the injured areas for early grafting.

The effect of the method of repeated readings on the reading rate and word recognition accuracy of deaf adolescents

This study examined the effects of the method of repeated readings (RR), a well-accepted remedial reading technique for improving the reading rate of hearing children, with deaf adolescents. Forty-two students from a midwestern residential school for the deaf were randomly assigned into treatment and control groups. The groups were equivalent with respect to age, level of hearing loss, reading achievement, and mental ability. All subjects read material previously determined to be at their instructional levels. Members of the treatment group were videotaped during the initial reading of an assigned passage, allowed to practice over three 15-minute sessions, then videotaped again during a final reading of the assigned passage. The control group differed only in that it practiced reading material other than the assigned passage. Reading rates and word recognition accuracy were recorded for the initial and final reading of each of five passages. Results indicated that the treatment subjects demonstrated significant improvement between pre- and posttesting regarding reading rate and two measures of word recognition accuracy. The performance of subjects engaged in nonrepetitive reading demonstrated minimal improvement. We discuss applicability of this procedure with a deaf population and implications for future research and practice.

Three-dimensional echocardiography using a transoesophageal imaging probe. Potentials and technical considerations

Appreciation of three-dimensional relationships could be useful in cardiac diagnosis, decision making and planning of surgery. However, current ultrasound techniques provide only two-dimensional views. A recently developed echocardiographic computerized tomography unit allows reconstruction of three-dimensional images from a series of transoesophageal slices. To evaluate the potentials and limitations of this technique we performed echo computer tomographic examinations in 104 patients with a total number of 227 scans. All but two patients tolerated the procedure well and no serious complications were encountered. Indications for echo computer tomography included coronary artery disease, valvular heart disease, atrial masses, myocardial infarction, mitral and aortic valve replacement, aortic aneurysm and congenital defects. Most of the anatomical structures could be visualized with the best results obtained for the left atrium, the left ventricular outflow tract and the aortic and mitral valve apparatus. However, a variety of technical factors must be considered to achieve optimal results and to avoid misinterpretation. In 86% of patients the underlying pathology could be visualised by echo-computed tomography, particularly congenital defects such as those of the atrial or ventricular septa, but mitral valve pathologies provided the best results. In these cases three-dimensional imaging led to a better perception and understanding of structural relationships. In conclusion, despite current limitations in data acquisition, processing and computing power, echo computer tomography has the potential to provide relevant information in selected clinical settings.

Modification of layered atelocollagen: enzymatic degradation and cytotoxicity evaluation

Two kinds of layered atelocollagen materials cross-linked with hexamethylene diisocyanate (HMDIC), starch dialdehyde and glyoxal were enzymatically treated by bacterial collagenase. Evaluating collagenase digestion assay for these material showed progressive differences, particularly in the group of samples cross-linked with HMDIC. This should offer the possibility of programmed enzymatic degradation. These materials may be toxicologically acceptable as proven by the short-term test used for cytotoxicity evaluation.

Cardiac troponin T release in multiply injured patients

Cardiac troponin T (cTnT), a new marker of myocardial tissue damage, was investigated in 32 consecutive multiply injured patients. cTnT, creatine kinase (CK) and CK isoenzyme MB (CK-MB) mass concentrations were measured immediately after admission, 12 and 24 h later and daily thereafter for 4 days. We found a moderate increase in cTnT in 22 patients (72 per cent; peaks: 0.6-5.1 micrograms/l). In only four of these 22 patients did the CK-MB mass/CK index indicate myocardial injury. ST-T alterations and arrhythmias did not occur significantly more frequently in patients with increased cTnT plasma concentrations or positive CK-MB mass/CK index. We found a moderate increase in cTnT in 72 per cent of all patients with multiple injuries, but we found no association between an increase in cTnT and the occurrence of electrocardiographic changes and arrhythmias.

Considerations and problems in the development of the mini-spindle pump

The premise for the development of the mini-spindle pump, planned as an implantable device for assisted circulation, was to transport 4 L of water/min in mock circulation with a speed of 12-15,000 rpm against an afterload of 90 mm Hg. After calculations, the resulting first prototype had a spindle rotor with 3 threads (outer diameter, 18 mm; inner diameter, 6.2 mm; length, 45 mm) in a U-shaped housing, driven by an electric motor with a cooling system. In mock circulation, this pump moved 7.8 L of water/min at 18,000 rpm. To avoid animal experiments, its influence on the blood was tested in a Maxima oxygenator. The device circulated 4.2 L of blood/min with the same speed. Because of its high traumatic hemolysis rate (> 250 mg% of free hemoglobin after 7 h of pumping), the rotor was modified, first without effect at 2.5 threads and then at 4 threads. In addition, in this third prototype, the flow direction was reversed. This prototype was more effective (4.3 L of blood/min at 12,000 rpm in the oxygenator) and the hemolysis rate, after a pumping duration of 8 h, could only be reduced to 180 mg% of free hemoglobin. As a result, a fourth prototype was developed (i.e., the U-shape of the housing was abandoned). This device functioned better than the third prototype (4.5 L of blood/min at 12,000 rpm in the oxygenator), but the blood trauma increased (220 mg% of free hemoglobin after 7 h of pumping).(ABSTRACT TRUNCATED AT 250 WORDS)

Zn2Mg alkaline phosphatase in an early ptolemeic mummy

Bone samples of a ptolemeic mummy have been employed to study the mode of conservation on the intactness of Zn2Mg alkaline phosphatase in both structure and catalytic activity. A protein of M(r) = 190 +/- 10 kDa being identical to the 200 kDa enzyme of fresh human bones was successfully isolated. Regardless of age 200 kDa protein bands and a distinct subunit at 60 kDa were seen in SDS-PAGE electrophoresis. The 200 kDa band was also monitored by activity staining. The specific activity was 120 mU/mg and 65% of the respective activity obtained in the identical preparation using fresh human tibia or rib. The enzymic activity was inhibited in the presence of 1,10-phenanthroline and L-homoarginine. Radiocarbon dating supported the assignment of the mummy to the early ptolemeic period. Among the many bactericidal and fungicidal components employed for mummification were aromatic alcohols, mono- and sesquiterpenes. Pistachio resin was the major balm resin used. The microbiological sterility of the bone surface was ascertained by independent bacterial and fungal examinations.

Effect of lung transplantation on right and left ventricular volumes and function measured by magnetic resonance imaging

To evaluate the effect of lung transplantation on right ventricular (RV) and left ventricular (LV) volumes and function, magnetic resonance imaging (MRI) was performed in 11 patients before and 6 to 24 months after single (n = 7) or double (n = 4) lung transplantation as well as in 15 healthy control subjects. Prior to transplantation, RV end-diastolic (RVEDVI, ml/m2) and end-systolic (RVESVI, ml/m2) volume indices were significantly increased in patients compared with those in control subjects. RV ejection fraction (RVEF, %), although within the lower normal range, was significantly reduced. In contrast, LV volume indices (ml/m2) were significantly smaller in patients than in control subjects, whereas LV ejection fraction (LVEF, %) was not different from that in normal subjects. After lung transplantation, MRI revealed a significant reduction in RVEDVI from 73 +/- 29 to 54 +/- 14 (p = 0.03) and RVESVI from 38 +/- 23 to 20 +/- 6 (p = 0.01) with a concomitant significant increase in RVEF from 48 +/- 14 to 63 +/- 6 (p = 0.01). Consecutively, the LV expanded to normal (LVEDVI from 49 +/- 12 to 65 +/- 14, p = 0.01; LVESVI from 23 +/- 9 to 28 +/- 7, p = 0.05), whereas LVEF remained unchanged (55 +/- 9 versus 56 +/- 8).