Subset distinct richness reduction and clonal expansion of human CD4+ and CD8+ αβ TCR repertoires with aging

A competent T-cell receptor (TCR) repertoire contains TCRs recognizing both novel and experienced antigens. It is widely believed that the human TCR repertoire declines with age, but its precise change in size and clonal distribution with age has not been fully determined. Here, we investigated how the size and content of TCR repertoire changes with age by analyzing the TCR repertoire of human CD4+ and CD8+ T cells and their naïve and memory subsets from 30 healthy adults aged from 25 to 85 at first visit and an average of 9-year follow-up as second visit by RNAseq. First, we calculated abTCR repertoire changes with age and found a profound reduction of the TCRa and TCRb richness in naïve CD8+ T cells and an increase of clonal expansion especially in memory CD8 T cells compared to CD4+ T cells. We also study the degree of overlap of TCRa/b repertoire between naïve and memory T cells in each subject at the same visit and found little overlap of TCRa/b unique sequences between naïve and memory CD4 T cells and ~40% of the total TCRs in CD8 T cells. Moreover, we showed elevated overlap of TCR sequences between two visits in both CD4 and CD8 T cells with memory CD8 T cells as the highest. Finally, we determined the degree of TCR clonotypes shares among different subjects via the analysis of the sharing of TCR sequences in the 30 healthy adults. As results, we observed increased sharing of identical TCR between CD4 and CD8 T cells suggesting that the public clonotypes may share with the common pathogens shared in the population, particularly in the old population. Our findings showed more profound reduction in the CD8+TCR repertoire with age compared to CD4+ TCR repertoire. All together provide evidence of ab TCR sequence-based age-associated changes of T cells and their subsets.

Optimising the management of choroidal neovascularisation in Asian patients: consensus on treatment recommendations for anti-VEGF therapy

In Asian countries, age-related macular degeneration (AMD), specifically wet AMD or choroidal neovascularisation (CNV), is an important cause of blindness and visual handicap. Vascular endothelial growth factors (VEGF) play an integral role in the development of CNV and thus provide an important therapeutic target. Current treatment paradigms for neovascular AMD recognise the place of photodynamic therapy (PDT) in the management of this condition. However, combination therapy targeting different pathways to produce a synergistic effect may result in improved visual outcomes and reduced duration of treatment. Anti-VEGF therapy has greatly improved treatment outcomes in patients with CNV, and a growing body of evidence supports the role of these agents as monotherapy or in combination with PDT. In particular, anti-VEGF may be a first-line treatment option in certain types of subfoveal myopic CNV as well as for classic and occult juxtafoveal and subfoveal CNV. The implementation of evidence-based medicine into current clinical practice is paramount to improving patient care. The authors, who are also members of the Singapore Medical Retina Advisory Board, outline the consensus points and recommended treatment algorithms based on currently available knowledge to provide a structured management approach to the treatment of Asian patients with CNV.

Computer-based detection of diabetes retinopathy stages using digital fundus images

Diabetes mellitus is a heterogeneous clinical syndrome characterized by hyperglycaemia and the long-term complications are retinopathy, neuropathy, nephropathy, and cardiomyopathy. It is a leading cause of blindness. Diabetic retinopathy is the progressive pathological alterations in the retinal microvasculature, leading to areas of retinal nonperfusion, increased vascular permeability, and the pathological proliferation of retinal vessels. Hence, it is beneficial to have regular cost-effective eye screening for diabetes subjects. Nowadays, different stages of diabetes retinopathy are detected by retinal examination using indirect biomicroscopy by senior ophthalmologists. In this work, morphological image processing and support vector machine (SVM) techniques were used for the automatic diagnosis of eye health. In this study, 331 fundus images were analysed. Five groups were identified: normal retina, mild non-proliferative diabetic retinopathy, moderate non-proliferative diabetic retinopathy, severe non-proliferative diabetic retinopathy, and proliferative diabetic retinopathy. Four salient features blood vessels, microaneurysms, exudates, and haemorrhages were extracted from the raw images using image-processing techniques and fed to the SVM for classification. A sensitivity of more than 82 per cent and specificity of 86 per cent was demonstrated for the system developed.

Age-related macular degeneration in Singapore

INTRODUCTION

This study aimed to describe the morphology of age-related macular degeneration (AMD) as well as to obtain an estimate of the population-based incidence rate in Singapore.

METHODS

This is a retrospective hospital-based study of AMD cases seen in 1991 and 1992 at the Singapore National Eye Centre (SNEC), a tertiary eye centre. All case notes recorded with the International Classification of Diseases, ninth revision, clinical modification code '362.5', which is 'degenerations of the macula', were retrieved and analysed. Only case notes of patients who were aged 50 years and above and with documented AMD were included in the study.

RESULTS

There were 41 (21.8 percent) patients with drusen alone, 39 (20.7 percent) with dry AMD and 108 (57.5 percent) with exudative AMD. The morphology of the disease was similar among the Chinese and non-Chinese and there were no gender differences. A significant majority of patients with dry and exudative AMD had legal blindness at presentation (p-value is less than 0.0001). Notably, 27 (33.3 percent) patients with exudative AMD had improved vision with time. In comparison, the majority of patients with dry AMD or drusen alone tended to have the same or worsening visual acuity over time. The two-year SNEC hospital incidence rate of AMD in 1991-1992 was 0.38 percent or equivalent to 3.8 per 1,000 new cases seen at SNEC. The estimated population-based incidence rate of exudative AMD was 0.02 percent.

CONCLUSION

The population incidence of exudative AMD is lower but comparable to the Western population. Patients with exudative AMD tend to have poorer vision as compared to patients with geographical atrophy or drusen. The proportion of exudative AMD to geographical atrophy appears to be higher than in the West.

Comparison of laparoscopic and open adrenalectomy--a Singapore experience

OBJECTIVE

We present our experience with laparoscopic adrenalectomy for benign adrenal diseases and compare clinical outcomes with the conventional open approach.

METHODS

Between 1990 and 2001, two consecutive series of patients who underwent adrenalectomy for small, benign adrenal diseases were reviewed retrospectively. Patients with large tumours(> 7 cm), cancer and phaeochromocytoma were excluded. Fifty-eight patients underwent laparoscopic adrenalectomy and 48 patients had open surgery for benign adrenal diseases. Perioperative and postoperative records of both approaches were reviewed.

RESULTS

The two groups were comparable in terms of patient age, sex, weight and side of lesion.The common indications for surgery were Conn's syndrome and Cushing's syndrome. The sizes of tumour were comparable between the laparoscopic and open groups (mean, 2.1 cm vs 2.4 cm). Despite the longer operating time (mean, 128 minutes vs 87 minutes), the postoperative morbidity, parenteral analgesic requirement and length of postoperative hospital stay (3.2 days vs 7.2 days) were less inpatients undergoing laparoscopic adrenalectomy. Patients also enjoyed earlier return to oral intake and ambulation. There were fewer complications in the laparoscopic group. There was no conversion to open surgery.

CONCLUSION

Laparoscopic adrenalectomy is safe and has become the treatment of choice for small, benign adrenal lesions at our institution.

An unusual presentation of acute scrotum after appendicitis

Acute scrotum following perforated appendicitis is a rare complication. This usually occurs in the presence of a patent processus vaginalis in children. We report a case of acute scrotum presenting after appendectomy for perforated appendicitis in a young adult.

Clinics in diagnostic imaging (46). Renal cell carcinoma in acquired cystic kidney disease

Acquired cystic disease of the kidney and renal cell carcinoma are associated with chronic renal failure. In recent years, there has been increased incidental detection of renal tumours through the liberal use of ultrasonography (US) and computed tomography (CT). A 40-year-old man suffering from chronic renal failure and who was being treated with haemodialysis for six years, was found to have a complex cystic lesion on US and CT. Nephrectomy was performed and the lesion was confirmed to be renal cell carcinoma associated with acquired cystic kidney disease. The current role of imaging in the management of affected patients are discussed.

A case of accelerated development of proliferative diabetic retinopathy in a woman with type 2 diabetes mellitus after pregnancy

Whilst it is recognised that diabetic retinopathy is a consequence of prolonged elevation of blood glucose levels, recent studies suggest rapid normalisation of blood sugar as a causal factor in accelerating its development. In this case report, a non-insulin dependent diabetic with poor blood glucose control but no retinopathy in early pregnancy had normalisation of glucose control by the third trimester. However, glucose control deteriorated rapidly postnatally, and she had a sudden blurring of vision three months after delivery of her baby, at which time severe proliferative diabetic retinopathy was diagnosed. The reason for the unusually rapid development of proliferative retinopathy was uncertain, but appeared to have a temporal association with the deterioration of her glycaemic control postnatal after a period of strict diabetes control in the perinatal period.

Laparoscopic adrenalectomy: experience with transabdominal and retroperitoneal approaches

OBJECTIVES

To study the patient outcomes of various approaches on 14 consecutive patients who had laparoscopic adrenalectomy surgery between October 1995 and March 1997.

METHODS

The patients comprised 5 men and 9 women (mean age 46.2 years, range 32 to 61) with varying diagnoses. Eleven patients had Conn's syndrome, 1 had Cushing's syndrome, 1 had a nonfunctioning adrenal adenoma, and 1 had an adrenal myelolipoma. The adenomas were confirmed by hormonal assays, biochemical tests, and computed tomography (CT) imaging. Seven adenomas were sited on the right and seven were sited on the left. We used two alternative approaches: a transabdominal approach (8 patients) and a retroperitoneal approach (6 patients).

RESULTS

None of the procedures required conversion to open surgery, nor was there any procedure-related complication. Blood loss was minimal. All the lesions were benign on final histology. The mean operating time was 135 minutes (range 80 to 190). The postoperative period was without significant complications, with patients reporting minimal pain. Patients were able to achieve an early return to oral intake and preoperative activity. The postoperative hospital period ranged from 1 to 10 days.

CONCLUSIONS

We believe laparoscopic adrenalectomy to be a viable option in the removal of benign adrenal lesions. It is a safe technique when performed by experienced practitioners and results in faster recovery. The key advantage to this technique is its minimally invasive approach and decreased hospital costs.

Trabeculectomy--success rates in a Singapore hospital

Previously published papers on the success of trabeculectomy as a treatment for glaucoma show success rates between 67% and 84%. The success rate of trabeculectomy in Afro-Carribean patients was observed to be lower than in Caucasian patients. It has been commonly believed that the success rate of trabeculectomy in Oriental/Asian eyes would lie somewhere between these. We reviewed the records of 51 consecutive trabeculectomies performed in the National University Hospital, Singapore and found that our success rate was lower-43.1% overall and 48.7% for primary glaucomas.

Endogenous nitrogen oxides and bronchodilator S-nitrosothiols in human airways

Recent discoveries suggesting essential bioactivities of nitric oxide (NO.) in the lung are difficult to reconcile with the established pulmonary cytotoxicity of this common air pollutant. These conflicting observations suggest that metabolic intermediaries may exist in the lung to modulate the bioactivity and toxicity of NO.. We report that S-nitrosothiols (RS-NO), predominantly the adduct with glutathione, are present at nano- to micromolar concentrations in the airways of normal subjects and that their levels vary in different human pathophysiologic states. These endogenous RS-NO are long-lived, potent relaxants of human airways under physiological O2 concentrations. Moreover, RS-NO form in high concentrations upon administration of NO. gas. Nitrite (10-20 microM) is found in airway lining fluid in concentrations linearly proportional to leukocyte counts, suggestive of local NO. metabolism. NO. itself was not detected either free in solution or in complexes with transition metals. These observations may provide insight into the means by which NO. is packaged in biological systems to preserve its bioactivity and limit its potential O2-dependent toxicity and suggest an important role for NO. in regulation of airway luminal homeostasis.

The challenge of eye disease: the patient's perspective

An educational symposium was organized to allow patients to be instructors by encouraging them to discuss their conditions, how they perceived their eye problems and the care they received, and the effect of their experience on their lives. Patients repeatedly stressed the need they felt for more time to discuss their disorders and more communication at all levels. An increasing use of patient information material, using printed materials and video, may partially alleviate the problem of a lack of communication.

Idiopathic subretinal neovascularization

Idiopathic subretinal neovascularization is a potentially blinding condition and often strikes patients in their prime of life. It appears to be seen in more females, at an earlier age than males. Treatment is possible by photoablation of the subretinal new vessel by Argon or Yag laser. There is a clinical impression that Argon laser is more effective than the Yag laser for this purpose.

Implantation and diabetes: analysis of 525 cases

This is a retrospective study of 525 posterior chamber implants in diabetics performed by A S M Lim and B C Ang of Singapore. The patients were reviewed by visiting ophthalmologists--J E Kennedy (Sydney), M Ngui (East Malaysia) and P M Hart (Belfast). This study did not show any significant difference in the complication of post-operative visual acuity between diabetics and non-diabetics. 95% obtained 6/12 vision or better when pre-existing disease was excluded. It also showed that posterior chamber implants can be inserted in eyes with maculopathy or proliferative retinopathy if laser treatment was effectively done before or after surgery.

31P NMR studies in Duchenne muscular dystrophy: age-related metabolic changes

To evaluate possible progressive metabolic changes in Duchenne muscular dystrophy, we used 31P nuclear magnetic resonance spectroscopy to measure high-energy phosphate compounds and phosphorylated diesters (PDE) in resting gastrocnemius muscle of 14 Duchenne patients and 10 normal boys. The patients had higher inorganic phosphate (Pi), intracellular pH, and PDE; and lower phosphocreatine (PCr) and PCr/Pi ratio; ATP was not significantly different. The patients showed significant age-related decreases in PCr and PCr/Pi, and increases in Pi and PDE, but ATP did not change. In normal boys, ATP increased with age, but PCr and Pi did not. These studies imply progressive metabolic deterioration in Duchenne dystrophy.

Rickets associated with long-term anticonvulsant therapy in a pediatric outpatient population

Over a 12-month period, an ambulatory pediatric population receiving long-term anticonvulsants was surveyed for the presence of biochemical and radiologic rickets. There were 74 treated children and 95 matched controls. Elevations of serum alkaline phosphatase activity occurred in 31 of the 74 (42%) treated children (23 of 47 children between 2 and 10 years and 8 of 21 children between 10 and 16 years). This frequency of abnormal values was significantly greater than that which occurred in our control population. Calcium and phosphorus abnormalities were minimal in both treated and control populations. Radiologic rickets occurred in 6 of the 74 (8%) of the treated children and in none of the control population. Neither the severity of the rickets nor the degree of hyperalkaline phosphatasemia were correlated with age of the patient, duration, and/or dose of anticonvulsant therapy.