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Biomedical subjects

J A Myburgh

Publications and source records attributed to J A Myburgh.

At least 55 records · Page 3Linked to original sources
PubMed1994

Tumour kinetics in breast cancer.

In vivo bromodeoxyuridine was used to measure the 'bromo' labelling index (LI,%), the duration of the S-phase (Ts, hours) and the potential tumour doubling time (Tpot, days) in women with stages I-IV breast cancer. These were studied in relation to lymph node status, tumour size, histological grade, oestrogen receptor status (ER), ploidy and S-phase fraction (SPF). In our patients, a LI of 10%, a Tpot of 2 days or an SPF of 9-10.5% predicted aggressive breast cancer. The LI was significantly higher (5%) in ER-negative than in ER-positive (2%) tumours (P = 0.03). There was a trend towards increased DNA synthesis in cancers with an SPF over 10% (P = 0.08). ER-negative breast cancers over 2 cm in diameter had shorter median Tpots of 5.3 days (P = 0.02) and 8 days (P = 0.05) compared with smaller, ER-positive tumours. A trend towards faster growth rates was seen in lymph node-positive, high-SPF (> 10%) breast cancers. Tumour kinetics may have additional prognostic value in the selection of node-negative patients for adjuvant therapy.

Breast Neoplasms↗
PubMed1994

Renal allograft preservation: a comparison of University of Wisconsin solution and of hypothermic continuous pulsatile perfusion.

A study was performed to compare early allograft function in kidneys preserved with University of Wisconsin (UW) solution to kidneys preserved by hypothermic pulsatile perfusion. The study consisted of two sets of data. The first set was a donor-paired study (matched data) of 30 heart-beating, hemodynamically stable donors. After removal from the donor each cooled kidney was individually prepared for preservation. One kidney was flushed with +/- 500 ml of UW solution and stored in UW solution on slushed ice. The other kidney was continuously perfused with cooled (4-6 degrees C) cryoprecipitated plasma. The kidneys were transplanted into suitable recipients in a random sequence. Twelve donors were excluded from the study because one or both kidneys were transplanted into recipients who had previously been transplanted. The remaining 36 kidneys were implanted into two similar groups after a mean of 19 hours in the pulsatile perfusion group and 18 hours in the UW solution group. The second set of data consisted of all the kidneys preserved in UW solution (n = 62) at our institution and of 57 kidneys preserved by hypothermic continuous pulsatile perfusion during the same period (mixed data) and was used to evaluate the effect of prolonged preservation (longer than 24 hours) on delayed graft function. Both of these groups were also comparable. Acute tubular necrosis (ATN) was defined as the need for dialysis during the 1st week after transplantation, and delayed function as the delayed clearance of creatinine during the early post-operative phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1993

The Hepp-Couinaud approach to strictures of the bile ducts. I. Injuries, choledochal cysts, and pancreatitis.

OBJECTIVE: The results of operative repair of benign strictures of the bile duct after cholecystectomy, right hemihepatectomy, vagotomy and antrectomy, choledochal cysts in adults, and chronic pancreatitis, with particular reference to the use of the Hepp technique for hilar strictures and without the use of transanastomotic tubal stenting, were analyzed in 44 patients. SUMMARY BACKGROUND DATA: End-to-side bilio-enteric anastomoses have been reported to be associated with restricturing and reoperation in 12% to 25% of cases and operative morbidity and mortality rates of 10% and 5% to 8%, respectively. Long-term transanastomotic tubal stenting is widely practiced in an attempt to prevent or diminish anastomotic stricturing. METHODS: The Hepp technique of wide, accurate, mucosa-to-mucosa anastomosis between the left hepatic duct and a jejunal Roux loop was used in 28 patients with hilar bile duct strictures. The same technical principle of wide side-to-side anastomosis was used in most of the lower strictures. Patients have been observed for 1 to 14 years (median, 7 years). RESULTS: The operative mortality rate was 7% (3 patients), but only 2.4% (1 patient) in 41 noncirrhotic patients. Two patients who had undergone standard end-to-side hepaticojejunostomy required reoperation (Hepp procedures) for recurrent strictures. No recurrent strictures occurred with the use of the Hepp technique for hilar strictures or wide side-to-side anastomosis for lower strictures. None of these patients experienced episodes of ascending cholangitis. CONCLUSIONS: The Hepp approach provides a safe, durable, and highly effective solution to the problem of strictures of the bile duct, including hilar strictures. Transanastomotic tube stenting is not necessary.

Adolescent↗
PubMed1993

Treatment of pancreatic ascites and external pancreatic fistulas with a long-acting somatostatin analogue (Sandostatin).

Prior to the advent of somatostatin conservative therapy for pancreatic fistulas, treatment included intravenous nutritional therapy with nothing per mouth and therapeutic agents to diminish pancreatic secretions. None of these modalities were uniformly successful. A prospective study to evaluate the efficacy of a long-acting somatostatin analogue (Sandostatin) was carried out. 18 patients-10 with pancreatic ascites and 8 with external pancreatic fistulas-were treated. The ascites resolved in 9 of 10 patients in a mean period of 22 days (+/- 3 days). The external fistulas were all high output fistulas and resolved in 7 of 8 patients. Mean period for closure was 23 days. There were no side effects associated with Sandostatin. Sandostatin has made a major impact on the conservative treatment of pancreatic ascites and is an important adjunct to the management of external pancreatic fistulas. It is emphasised however that surgery may be required for the underlying pancreatic disease. In this regard close surveillance of these patients is necessary.

Adult↗
PubMed1993

Successes and failures of endoscopic injection haemostasis for bleeding peptic ulcers. A prospective clinical study.

Fifty-two consecutive patients with upper gastrointestinal haemorrhage, shock (systolic blood pressure less than 100 mmHg) and a peptic ulcer showing endoscopic stigma of recent haemorrhage underwent attempts at endoscopic haemostasis. The ulcers were injected with a dilute solution of adrenaline followed by 5% ethanolamine oleate. Active bleeding was present in 22 patients (42%) at initial endoscopy. Bleeding was controlled in 40 patients (77%) in hospital. Failure occurred more frequently in duodenal ulcers than gastric ulcers (46% v. 7%; P < 0.004), and in giant (more than 2 cm diameter) duodenal ulcers (6/7) than smaller duodenal ulcers (3/15). We recommend early surgery for large posterior duodenal ulcers in preference to endoscopic injection methods.

Adult↗
PubMed1992

Ventilation/perfusion indices do not correlate with the difference between oxygen consumption measured by the Fick principle and metabolic monitoring systems in critically ill patients.

OBJECTIVE: To determine whether the difference between oxygen consumption (VO2) measured by metabolic gas monitoring systems and by the Fick principle is related to venous admixture, deadspace/tidal volume ratio, or alveolar-arterial oxygen tension gradient in critically ill patients. DESIGN: A prospective study. SETTING: An 11-bed general ICU in a 900-bed teaching hospital. PATIENTS: Twenty critically ill patients admitted to the ICU who required mechanical ventilation, right heart catheterization, and arterial and mixed venous gas measurements for normal clinical management. RESULTS: Thirty-three recordings were analyzed. The mean VO2 measured by the metabolic gas monitoring system was 308 +/- 63.9 (SD) mL/min and was significantly greater than the mean VO2 measured by the Fick principle of 284 +/- 72.0 mL/min. The difference between the two measurements of 24.3 +/- 47.6 mL/min correlated poorly with venous admixture (r2 = .0009), dead-space/tidal volume ratio (r2 = .0064) and alveolar-arterial oxygen tension gradient (r2 = .017). CONCLUSIONS: If the difference in VO2 measured by metabolic gas monitoring systems and the Fick principle is due to intrapulmonary VO2 then in critically ill patients the ventilation/perfusion indices of venous admixture, deadspace/tidal volume ratio and alveolar-arterial oxygen tension gradient correlate poorly with intrapulmonary VO2.

Adult↗
PubMed1992

Enhanced spontaneous and induced LAK function in baboons receiving total lymphoid irradiation (TLI).

TLI has potent immunosuppressive effects, but there is concern over its possible carcinogenic properties. The aim of the study was to assess to what degree TLI may compromise natural killer (NK) and lymphokine activated killer (LAK) cell function. There was a significant increase (P less than 0.0001) in both NK-cell function (measured against K562 targets) and spontaneous LAK-cell function (measured against DAUDI targets) in fresh blood lymphocytes throughout a course of 8 x 100 cGy fractionated TLI. This may be related to a three- and sevenfold increase, respectively, in CD16+ CD8- and CD56+ CD2- cell frequencies over the same period. Mitogen-induced interleukin 2 (IL-2) synthesis from blood lymphocytes was inhibited by up to 75% with as little as 100 cGy of TLI. Expression of IL-2 receptors on fresh lymphocytes did not vary and remained low. Therefore spontaneous LAK occurrence appeared to be triggered through an IL-2-independent pathway. The in vitro addition of IL-2 verified that cells retained their ability to respond to this lymphokine resulting in greatly enhanced induced LAK function. This was most probably mediated by CD56+ cells which were found to readily express IL-2 receptors upon mitogen stimulation. In conclusion, fractionated low-dose TLI appears to enhance MHC unrestricted immune surveillance in a manner independent of IL-2 production.

Animals↗
PubMed1992

Derived oxygen saturations are not clinically useful for the calculation of oxygen consumption.

In critically ill patients, oxygen consumption (VO2) and delivery (DO2) are used to determine optimal haemodynamic management and to grade severity of illness. VO2 may be measured by indirect calorimetry with metabolic gas monitoring systems or derived using the reverse Fick principle. Oxygen saturation (SaO2) may be measured directly by co-oximetry or derived by equations for incorporation into reverse Fick equations. A prospective study comparing VO2 measured by these methods was performed in 20 critically ill patients. The mean VO2 measured by the metabolic gas monitoring system (308 +/- 63.9 ml/min) was significantly greater than that measured by reverse Fick using measured SaO2 (284 +/- 72.0 ml/min) (P < 0.01). This difference may be due to intrapulmonary VO2. When SaO2 was calculated from three logarithmic equations and incorporated into the reverse Fick equations, calculated VO2's were significantly greater (P < 0.001) than those measured by indirect calorimetry. Correlation was poor and wide limits of agreement (-118 to +350 ml/min) were demonstrated. VO2 should ideally be measured by indirect calorimetry in the critically ill, or if reverse Fick is used, SaO2 should be measured by co-oximetry as the use of equations for clinical measurement of SaO2 is clinically suspect.

Adult↗
PubMed1991

The relevance of more sensitive ancillary crossmatch techniques in predicting early cadaver renal graft outcome.

The predictive value of varying levels of antibody activity, its class and antigen specificity in sera of 81 recipients of cadaver renal allografts was evaluated. Recipients for transplantation were selected on the basis of a negative dye uptake T-cell crossmatch, after which the more sensitive 51Cr release technique was employed in a blind study using unseparated donor target cells. Recipient sera with peak panel reactivity and current samples were evaluated before and after reduction with dithiothreitol to destroy the IgM subclass. Double absorption with pooled platelets allowed antibodies against HLA class I antigens to be distinguished from those against HLA class II/non-HLA antigens. Optimal levels of cytotoxicity were established, giving a sensitivity of 73%. Data were assessed in terms of positive predictive value, and showed that conventional T-cell crossmatching is adequate for the primary transplant group, but more sensitive ancillary tests are indicated for regrafts. In this category of patients, IgG antibodies, whether against HLA class I antigens or HLA class II/non-HLA antigens, were highly predictive of early graft loss (positive predictive value 50%-100%). Using this protocol for patient selection, 1-month graft survival would have improved from 73% to 96%.

Adolescent↗
PubMed1991

A prospective comparison of a percutaneous tracheostomy technique with standard surgical tracheostomy.

A prospective non-randomized study was undertaken to compare, in intensive care patients, the safety and utility of a percutaneous tracheostomy technique performed at the bedside with a surgical tracheostomy technique performed in the operating room. During a 21 month period, 153 percutaneous tracheostomies were performed. Complications occurred in 6 patients (3.9%). Secondary wound haemorrhage occurred in 4 patients and primary wound haemorrhage occurred in 2 patients. During the same period, 74 surgical tracheostomies were performed. Complications occurred in 14 patients (18.9%) which included tracheal obstruction, haemorrhage, pneumothorax, wound infection, wound breakdown and one death. In comparison to surgical tracheostomies, percutaneous tracheostomies were rapidly and easily performed at the bedside and were associated with significantly fewer complications.

Adolescent↗
PubMed1991

The P50 is reduced in critically ill patients.

A prospective study was designed to measure the P50 in 20 critically ill patients, and compare it with the P50 measured in 20 normal individuals. Arterial blood gases, lactate, haemoglobin (Hb) and phosphate (PO4) levels were also measured and compared with the P50 in the critically ill patients. The mean P50 of the critically ill patients was 24.5 mmHg (SD +/- 2.9) and was significantly lower than the mean P50 of 26.2 (SD +/- 2.2) in the normal individuals (p less than 0.05). In the critically ill patients, strong correlations were observed between the P50 and the arterial pH and base excess (BE) levels, with coefficients of 0.79 and 0.69 respectively whereas correlations between the P50 and arterial oxygen tension (PO2), carbon dioxide tension (PCO2), lactate, Hb and PO4 levels were poor, with correlations of 0.001, 0.008, 0.07, 0.13 respectively. It is concluded that the P50 is commonly reduced in critically ill patients, and has a strong correlation with arterial pH and BE.

Adult↗
PubMed1991

Properties of the isoenzyme forms A-1, A-2 and B of N-acetyl-beta-D-glucosaminidase purified from baboon kidneys.

Three forms of N-acetyl-beta-D-glucosaminidase (NAG: A, B and I) were separated from baboon kidney using Con A-Sepharose and DEAE-Trisacryl chromatography. 2. The A form was further purified into two forms A-1 and A-2 using hydroxylapatite chromatography and anodic PAGE. Both were homogeneous on SDS-PAGE and anodic PAGE but microheterogeneous on PAG-IEF, which could be eliminated by prior treatment with endoglycosidase H or glycopeptidase F. 3. The carbohydrate content accounted for some of this microheterogeneity since it varied from 31 for A-1 to 17% for A-2 and the sialic acid was 6 and 1%. Deamidation may also contribute since the acidic amino acids (29 mol%) and ammonia were high following acid hydrolysis. 4. The mol. wt for A-1, determined by SDS-PAGE, was 52.1 K. 5. The pH optimum was 4.55 and the pI4.97. 6. The optimum temperature for NAG A and B was 50 degrees and 42 degrees C, but B retained more activity above 55 degrees C. 7. The Km for N-acetyl-beta-D-glucosamine and -galactosamine for both isoforms was 0.497 and 0.627 mM respectively. 8. Several ions were found to be uncompetitive inhibitors. Ag+ and Pb2+ were the most potent having Ki values of 3.6 and 8.5 mM respectively. Acetate acted as a competitive inhibitor.

Acetylglucosaminidase↗