Biomedical subjects

J Lazarus

Publications and source records attributed to J Lazarus.

At least 19 recordsLinked to original sources

PubMed2003

Association of angiomyolipoma and oncocytoma of the kidney: a case report and review of the literature.

AIM: The association between renal carcinoma and angiomyolipoma is rare. Only 14 cases have been reported in the literature. The purpose of this paper is to present an additional case and review the literature on this association. PATIENT AND METHODS: A healthy 42 year old woman was found to have a left flank mass incidentally when she presented for a Papanicolaou smear. The computerised tomography scan revealed a left lower pole renal mass consistent with a renal cell carcinoma. A nephrectomy was performed and the patient recovered uneventfully. The nephrectomy specimen was processed routinely. In addition to haematoxylin and eosin staining, immunohistochemistry for CAM 5.2, vimentin, CD34, antismooth muscle actin, and HMB45 was carried out. Transmission electron microscopy was also performed. RESULTS: Macroscopically, the lower pole of the kidney contained a well circumscribed, non-encapsulated, tan coloured tumour with a large area of central haemorrhage measuring 10.5 cm. In addition, there was a 0.4 cm poorly circumscribed unencapsulated yellow nodule adjacent to the tumour. Microscopically, the larger tumour showed characteristic features of an oncocytoma. Numerous mitochondria were seen on electron microscopy. The smaller yellow nodule was an angiomyolipoma. CONCLUSIONS: This paper presents an additional case of oncocytoma associated with angiomyolipoma. Of the 15 cases described in the literature, three were associated with the tuberous sclerosis complex, all from a single study. In tuberous sclerosis, angiomyolipomas are more commonly associated with renal cell carcinoma. If angiomyolipomas are found incidentally in nephrectomy specimens together with other tumours, it is important to exclude tuberous sclerosis retrospectively.

Actins↗

PubMed2001

Prey scan at random to evade observant predators.

Anti-predator scans by animals occur with very irregular timing, so that the initiation of scans resembles a random, Poisson-like, process. At first sight, this seems both dangerous (predators could exploit the long intervals) and wastefull (scans after very short intervals are relatively uninformative). We explored vigilance timing using a new model that allows both predators and prey to vary their behaviour. Given predators that attack at random with respect to prey behaviour, constant inter-scan intervals minimize predation risk. However, if prey scan regularly to minimize their risk from randomly attacking predators, they become more vulnerable to predators that initiate attacks when the inter-scan intervals begin. If, in order to defeat this tactic, prey choose extremely variable inter-scan intervals, they become more vulnerable to predators who wait for long intervals before launching attacks. Only if predators can monitor the variability of inter-scan intervals and either attack immediately (if variability is too low) or wait for long intervals to attack (if variability is too high) does the empirically observed pattern of Poisson-like scanning become the optimal prey strategy.

Animals↗

PubMed2001

A luminescent bioassay for thyroid blocking antibodies.

OBJECTIVE: Thyroid blocking antibodies (TBAb) have a role in the development of hypothyroidism and in the neonate are responsible for transient hypothyroidism. Specific measurement of TBAb requires a bioassay, but current methods are lengthy and cumbersome. We describe a rapid luciferase-based method for the detection of TBAb using the lulu* cell line which is suitable for the provision of a clinical service PATIENTS AND MEASUREMENTS: Chinese hamster ovary (CHO) cells were transfected with human TSH-R together with G418 resistance and a cAMP responsive luciferase construct. Stable pools of transfected cells were selected and clones identified by limiting dilution. Clone lulu* gave the best response to stimulation by TSH and was used to develop a bioassay for TBAb. The luminescent bioassay conditions have been optimized and validated using 12 serum samples from patients found to be TBAb positive in a bioassay using an established method quantifying cAMP by radioimmunoassay (RIA). The effect of thyroid stimulating antibodies (TSAb) on the calculation of Inhibition Index (InI) using two previously described formulae have been investigated and we have used serum containing both TSAb and TBAb to investigate detection of TBAb in samples containing more than one type of activity. RESULTS: Lulu* displays a dose dependent increase in luciferase expression in response to stimulation with bovine (b) TSH which is more effective in serum free medium than in salt free buffer. TSH stimulated luciferase expression can be inhibited by TBAb in either serum or an immunoglobulin preparation. Using optimized assay conditions, challenging 10% serum against 1 U/l bTSH in culture medium, we have tested 31 euthyroid sera to determine a reference range: InI values >23% were considered positive. Twelve samples previously shown to contain TBAb by an established method quantifying cAMP by RIA were positive by the luciferase-based assay. Of control sera, 20/20 systemic lupus erythematosus, 13/14 rheumatoid arthritis, 12/12 multinodular goitre were negative. We demonstrated that if more complex formulae are used to calculate InI, false positive TBAb results can be obtained in samples containing only TSAb. Finally, when sera contain both TSAb and TBAb, the net activity of stimulating and blocking antibodies is detected in the bioassay. Where TSAb are also present, analysis of serum may be required at several dilutions to detect TBAb. CONCLUSIONS: We describe the production of a new cell line, lulu*, and its use to develop a luminescent bioassay for TBAb suitable for clinical use. Comparing two established methods of calculating TBAb, we found that they do not give identical results. In light of this, the high prevalence reported for TBAb in some studies has to be considered with caution.

Animals↗

PubMed2001

Abnormal serum free thyroid hormone levels due to heparin administration.

Fractionated or unfractionated heparin may produce artefactual elevation in measured concentrations of free thyroid hormones. Although the specific cause is unknown, it may be a consequence of displacement of thyroid hormones from their binding sites by free fatty acids liberated in vitro. We describe four cases of heparin-induced abnormalities in free thyroid hormone measurements where some diagnostic confusion was generated. Increasing physician awareness of this poorly appreciated entity may avert diagnostic confusion and unnecessary investigation.

Adult↗

PubMed2001