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Biomedical subjects

J M Low

Publications and source records attributed to J M Low.

At least 19 recordsLinked to original sources
PubMed2007

Abnormal kappa:lambda light chain ratio in circulating immune complexes as a marker for B cell activity in juvenile idiopathic arthritis.

Patients with juvenile idiopathic arthritis (JIA) have been shown to have elevated levels of circulating immune complexes (CICs) which correlated with disease activity. Our aim was to assess B cell activity by measuring the amount of and the kappa:lambda chain immunoglobulin light (L) chain ratio in CICs from JIA patients and to determine potential evidence for either an antigen-driven response or B-cell receptor editing. We used an enzyme-linked immunosorbent assay to measure kappa and lambda chains present in the CICs from the sera of patients with JIA. Statistical analysis was performed using Pearson's correlation, one-way ANOVA and Bonferroni post hoc analysis. Sera from 44 JIA patients were examined for the concentration of L chains in CICs. Healthy controls had a kappa:lambda chain ratio of 1.2:1, whereas this ratio was reversed among JIA subgroups with RF-positive polyarthritis (1:1.2), RF-negative polyarthritis (1:1.3), oligoarthritis (1:2.3) and systemic-onset arthritis (1:2.5). In addition, overall lambda chain selection was not significantly associated with a particular immunoglobulin heavy (H) chain and occurred with all immunoglobulin isotypes. We showed preferential selection of lambda chains contributing to the formation of potentially pathogenic CICs from JIA patients, of all onset types compared to healthy controls, in an H chain-independent manner. The reversal of kappa:lambda chain ratio within the JIA CICs and association with all immunoglobulin isotypes demonstrated the potential for L chain editing. Furthermore, we conclude that a reversal of the normal kappa:lambda chain ratio in JIA CICs may be used as a marker for increased B-cell activity.

Adolescent↗
PubMed2005

A role for the complement system in rheumatoid arthritis.

The production of autoreactive antibodies from self-reactive B cells results in the formation of immune complexes that deposit in tissue and fix complement, contributing to the pathogenesis of rheumatoid arthritis (RA). Earlier mouse models emphasize the importance of autoreactive antibodies formed against "self" proteins that serve as a source for T cell-mediated immune response, stemming from cross-reactivity and resulting in B cell activity. However, more recent models suggest the need for both autoantibodies and the initiation of the inflammatory cascade via the alternative complement pathway, which is unbridled as the cartilage lacks the usual regulatory proteins of the complement system. Furthermore, deficiencies in specific complement proteins could lead to an escape from negative selection by these self-reactive B cells. Moreover, the classical complement pathway establishes chemotactic gradients by which inflammatory cells follow and accumulate in the synovial fluid where they engulf immune complexes and release proteolytic enzymes. In addition, the processing of circulating immune complexes either via Fc receptor or CR1 and opsonization by complement fragments plays a key role in determining the fate of immune status. In addition, complement proteins are a major determinant in the size and solubility of an immune complex, which also affects clearance. The evidence regarding intra-articular activation of the complement system in RA provides the possibility to pharmacologically manipulate various parts of the complement system for therapeutic purposes and potential therapeutic targets for the control of inflammation and the prevention of joint destruction.

Animals↗
PubMed2001

Anesthetic management of renal cell carcinoma with inferior vena caval extension.

We present a case of a patient with renal cell carcinoma extending into the inferior vena cava. Preoperative diagnosis was facilitated by transthoracic and transesophageal echocardiography (TEE), and inferior venacavography. Intraoperatively, monitoring with continuous TEE was used. Preparation was made for cardiopulmonary bypass but surgery was successfully completed using extracorporeal venous shunting. We discuss the important aspects of preoperative diagnosis and the intraoperative anesthetic management of this case.

Anesthesia↗
PubMed1999

Differences in cognitive complexity of adolescents with foreclosed and achieved identity status.

The purpose of this study was to assess whether the complexity of the self-concept differs based on identity status in late adolescence. Adolescents in the achieved status have a strong sense of identity that has emerged following an intense period of exploration. Adolescents in the foreclosed status also have a strong sense of identity, but they have never been through a period of exploration. It was expected that adolescents in the achieved status would have more complex self-concepts than those in the foreclosed status. 62 university students were classified into the achieved or foreclosed identity status based on their scores on the Extended Version of the Objective Measure of Ego Identity Status-2. They then completed a trait sort to measure the complexity of their self-concepts. Complexity scores were calculated based on the H statistic, an index of dispersion derived from information theory. The results were as expected. Possible structural changes underlying the process of developing identity are presented, and the usefulness of structural self-concept models for studying development of identity is examined.

Adolescent↗
PubMed1996

The gene encoding ammonia monooxygenase subunit A exists in three nearly identical copies in Nitrosospira sp. NpAV.

The gene encoding ammonia monooxygenase subunit A (AmoA) was found in three copies of the genome of the chemolithotrophic soil bacterium, Nitrosospira sp. NpAV. The open reading frame and flanking regions of the three copies were isolated from digested size fractionated genomic DNA using oligodeoxyribonucleotide primers and polymerase chain reaction. The three gene copies of amoA were sequenced and the sequences compared to each other. The open reading frames and the upstream and downstream flanking regions were nearly identical in the three copies. All three copies were expressed in recombinant Escherichia coli strains from the indigenous promoter producing a product of approximately 30 kDa. All amoA copies encode 274 amino acid polypeptides which have similarity to the ammonia monooxygenase acetylene-binding protein from Nitrosomonas europaea.

Amino Acid Sequence↗
PubMed1996

Australian farm work injuries: incidence, diversity and personal risk factors.

Information on farm work-related injuries was sought to assist in the design of effective farm safety prevention programs. A telephone survey was conducted using a stratified random sample of 919 sheep/wool, beef cattle and dryland broadacre cropping farms from three shires in the wheat/sheep belt of New South Wales. The adjusted response rate was 84%. There were 425 reported injuries over an 18-month period. One in five farms reported at least one injury per year, while one in 12 farms reported at least one serious injury per year. Animal-related injuries were the largest major category for agent of injury, while the largest category for nature of injury was sprain and strain, recording almost one-quarter of all injuries. The farm workshop or shed was the most common location of injury, with more than 20% of all reported injuries occurring there. Personal risk factors thought to contribute to these farm work-related injuries were examined. The statistically significant personal risk factors for injury occurrence were age (and/or experience), previous injury status, body mass index, hours of sleep, a variable measuring daytime drowsiness and a variable measuring perceived stress.

Accidents, Occupational↗
PubMed1995

Plasma catecholamine levels during functional endoscopic sinus surgery.

Plasma adrenaline and noradrenaline concentrations were measured in 10 consecutive patients during functional endoscopic sinus surgery (FESS). Surgery was preceded by nasal packing with 5 ml 2% cocaine solution, followed by infiltration with 1:80,000 adrenaline and 2% lignocaine. All patients showed a marked rise in plasma adrenaline concentration within 4 min of commencing infiltration, which was not related to the patient's sex, age, weight, the total amount injected, nor the amount injected into the nose. Surgeons should be aware of this marked, but unpredictable, systemic absorption of locally infiltrated vasoconstrictors. Pulse and ECG monitoring should be considered mandatory for such procedures, even when surgery is performed under local anaesthesia.

Adolescent↗
PubMed1995

Video-assisted thoracoscopic surgery in the paediatric population.

OBJECTIVE: Video-assisted thoracoscopic surgery (VATS) is now widely practised in adults but there are few publications on its application in the paediatric population. METHODOLOGY: Retrospective review of the authors' experience with VATS in children under 16 years old during an 18 month period in a university teaching hospital. RESULTS: From September 1993 to March 1994, VATS was attempted in 14 patients. Five were unsuccessful because of pleural symphysis or inability to collapse the upper lung. Ten cases of VATS were successfully performed in the remaining nine patients (eight males, one female; age range from 22 days to 15 years old). These included two drainages and limited decortications for loculated pleural effusion, one guided drainage of pericardial effusion, one thymectomy for thymic hyperplasia, three wedge resections for metastatic pulmonary osteosarcoma and three bleb excisions and pleurodesis for primary spontaneous pneumothoraces. There were no intra-operative complications. There was one death from dysrhythmia following an uneventful wedge resection. The mean duration of chest tube drainage was 1.4 days and postoperative hospital stay 2.6 days excluding two patients who stayed for further medical treatment. CONCLUSION: VATS is a useful approach in selected cases but further development of this approach awaits refinement of anaesthetic technique and endoscopic instrumentation.

Adolescent↗
PubMed1995

Necrotising soft tissue infections as a complication of chickenpox.

Varicella gangrenosum, in which a necrotising soft tissue infection complicates the vesicular eruption of chickenpox, is rare. The condition may have devastating sequelae including disseminated intravascular coagulation and death. Survival is dependent on early diagnosis, adequate antibiotic coverage and, particularly, early surgical debridement. Three cases of varying severity are presented here together with a review of the available literature.

Adult↗
PubMed1994

One hundred and sixty-three consecutive video thoracoscopic procedures: the Hong Kong experience.

Video-assisted thoracoscopy (VAT) offers a new approach to the diagnosis and treatment of many thoracic conditions. From September 1992 to August 1993, a total of 163 VAT procedures were successfully performed on 108 patients (87 male, 21 female; age range from 12 to 77) which consisted of 42 bleb eliminations and 64 mechanical pleurodesis for spontaneous pneumothorax, 11 wedge resections for pulmonary nodules, three wedge biopsies for diffuse pulmonary infiltrate, four thoracic sympathectomies, resections of two mediastinal masses, three pericardial windows, 10 guided pleural biopsies for undiagnosed effusions, six guided drainage of empyema and haemothorax, 16 staging of intrathoracic tumours and two explorations for penetrating thoracic trauma. There was no procedure-related mortality. Complications included one recurrence for spontaneous pneumothorax, one re-exploration for bleeding (also by VAT approach), one wound infection, and six persistent air leaks for more than 10 days. The median duration of postoperative chest tube drainage was 2 days and the median hospital stay was 4 days. It was concluded that VAT is a safe and effective approach in thoracic surgery and with further refinement in instrumentation even more procedures will be technically feasible. The long-term results of VAT are being awaited in order to define its true merits in thoracic surgery.

Adolescent↗
PubMed1994

An unusual presentation of carcinoma of the gallbladder--case report.

Unusual modes of presentation of carcinoma of the gallbladder have been described in the literature. However, this is probably the first reported case of carcinoma of the gallbladder presenting with acute large bowel obstruction. This paper also reviews the literature pertaining to the clinical features and current treatment of carcinoma of the gallbladder. It continues to be a discouraging disease characterised by late diagnosis and a poor outcome.

Adenocarcinoma↗
PubMed1993

Effect of respiratory acidosis and alkalosis on plasma catecholamine concentrations in anaesthetized man.

1. Plasma concentrations of noradrenaline and adrenaline were measured in 11 anaesthetized patients during normocapnia, hypocapnia and hypercapnia. Hypocapnia was produced by deliberate hyperventilation and hypercapnia by adding carbon dioxide to the inspired gas mixture. 2. With a median (range) arterial partial pressure of carbon dioxide of 4.7 (4.2-5.2) kPa, the median (range) plasma concentration of noradrenaline was 0.41 (0.12-0.94) nmol/l and of adrenaline was 0.15 (0.05-0.31) nmol/l. 3. With an arterial partial pressure of carbon dioxide of 2.6 (2.2-3.3) kPa, there was no change in the plasma concentration of noradrenaline [0.37 (0.12-0.86) nmol/l] or that of adrenaline [0.16 (0.05-0.32) nmol/l]. 4. However, with an arterial partial pressure of carbon dioxide of 10.4 (7.6-13.2) kPa, there were significant increases in the plasma concentrations of both noradrenaline [1.13 (0.79-2.05) nmol/l, P < 0.01] and adrenaline [0.67 (0.20-2.92) nmol/l, P < 0.05]. 5. This is the first demonstration in man that respiratory acidosis causes an increase in plasma concentrations of catecholamines.

Adult↗
PubMed1993

An ethnic comparison of the sympathetic response to tracheal intubation.

The sympathetic response to orotracheal intubation was examined in five Europeans, 15 Chinese, and seven Nepalese male patients. Plasma adrenaline and noradrenaline concentrations were assayed using high performance liquid chromatography with colorimetric detection. There was a significant rise in noradrenaline concentrations following intubation in the Chinese and the concentrations decreased over 5 min. Similar increases were seen in the Europeans and Nepalese. The mean plasma catecholamine concentrations were comparable, which suggests that there are no ethnic differences in the groups studied. A wide interindividual variation of catecholamine concentrations was found.

Adolescent↗
PubMed1992

Plasma catecholamine levels following topical application versus infiltration of adrenaline for nasal surgery.

Plasma catecholamine concentrations were measured after vasoconstrictor solutions were administered either by instillation (Moffett's method) or by submucosal infiltration in twenty patients undergoing elective nasal surgery. Following infiltration with 4.4 ml of 1:80,000 adrenaline and 2% lignocaine, plasma adrenaline concentrations increased by 44.3 times to a peak of 9.9 nmol.l-1 (1813 pg.ml-1) within one minute. In contrast the peak level of adrenaline in the patients receiving Moffett's solution containing 1 ml of 1:1,000 adrenaline was 1.27 nmol.l-1 (232 pg.ml-1) occurring 10 minutes after instillation of the solution. The difference in the adrenaline concentrations between the groups was statistically significant (P less than 0.01). The lack of sympathoneuronal response was confirmed by simultaneous measurements of plasma noradrenaline concentrations, which did not change significantly. The operative field was subjectively assessed to be better in the infiltrated patients and the mean operating time and measured blood loss were less in this same group of patients.

Administration, Topical↗
PubMed1992

A successful peritoneovenous shunting of ascites using the great saphenous vein.

For the surgical palliation of massive ascites, a LeVeen or Denver shunt may be implanted to drain ascitic fluid from the peritoneal cavity into the circulation. But all commercial shunts are costly and depend on a synthetic valve to prevent blood refluxing into the peritoneal cavity. We report here the first patient with a malignant ascites that was successfully palliated by peritoneovenous shunting using the great saphenous vein as a biological valve.

Ascites↗
PubMed1991

Plasma catecholamines and oxygen consumption during weaning from mechanical ventilation.

Previous studies on oxygen consumption (VO2) during weaning from mechanical ventilation assumed that an increase in VO2 (delta VO2) reflected oxygen consumption by respiratory muscles (VO2RESP), and proposed delta VO2 as a weaning predictor. We measured VO2 CO2 production (VCO2) and plasma catecholamines in 20 short-term ventilated patients during weaning by SIMV and CPAP. delta VO2 as a percentage of VO2 during spontaneous ventilation (delta VO2%) ranged from 4.8% to 41.5%. VCO2 also increased and correlated with VO2. Plasma adrenaline and noradrenaline increased significantly to levels known to produce considerable increases in metabolic rate. Mean arterial pressure and heart rate concomitantly increased, but spontaneous minute ventilation decreased. Thus, since the increased plasma catecholamines are calorigenic, the assumption that delta VO2 represents VO2RESP is incorrect. Although mean delta VO2% of successfully weaned patients was significantly less than that of failure-to-wean patients, the wide scatter of individual values in the latter group excludes delta VO2% as an accurate weaning predictor.

Adult↗
PubMed1986

Studies of anaesthesia in relation to hypertension. VII: Adrenergic responses to laryngoscopy.

Arterial pressure and plasma catecholamine concentrations were measured in 16 normotensive and 10 hypertensive patients undergoing elective vascular surgery. Following induction of anaesthesia, both arterial pressure and plasma noradrenaline concentrations decreased in both groups. Following laryngoscopy, there was a moderate increase in arterial pressure in both normotensive and hypertensive patients. In normotensive patients, laryngoscopy was associated with a moderate increase in plasma noradrenaline concentration. There was no change in adrenaline concentration. By contrast, there was a marked increase in noradrenaline concentration, a moderate increase in adrenaline concentration and an arterial pressure response in the group of hypertensive patients. These data are consistent with transient sympathetic overactivity in hypertensive patients following noxious stimuli such as laryngoscopy.

Adrenergic beta-Antagonists↗