Adaptation of the disector method to rare small organelles in TEM sections exemplified by counting synaptic bodies in the rat pineal gland

The disector is the only objective method for quantifying particles of variable size in a given volume. With this method, cell organelles are identified on adjacent sections, but only those present in one section are counted. When counting extremely rare structures in transmission electron microscope sections (physical disector), the usual procedure of counting on electron micrographs is limited for economic reasons (e.g. micrographs highly outnumbering the investigated structures). Hence, to apply this unbiased stereological method, a modification of the physical disector concerning 3 aspects has been developed. (1) The prerequisite of screening large corresponding tissue areas (here ∼65000 μm²) was fulfilled by examining tissue areas along the edges of ultrathin sections. (2) The size of the counting frame was determined by measuring the lengths of the section margins (minus a guard area) by means of a Morphomat. This value was multiplied by the width of the investigated tissue zone, corresponding to the diameter of the electron microscope viewing screen. (3) Disector counting was carried out simultaneously on both sections (bidirectional disector) to improve efficiency. In the present study tiny synaptic bodies (SBs) were quantitated by disector in a rat pineal gland, yielding ∼30 SBs/1000 μm³. By contrast, single section profile counts of SBs amounted to 90 SBs/20000 μm². Since the presently described adaptation of the disector is time-consuming, it is proposed to determine a proportion factor allowing to estimate number of structures per volume based on single section profile counts. This would decrease the evaluation time by more than 50%.     

Response of blood prothrombin to vitamin K as a measure of hepatic function

L'auteur décrit le cas d'une femme de 31 ans, souffrant depuis 4 ans d'un état post-encéphalitique et qui réagit à l'administration d'acide nicotique par une intense hyperémie cutanée, exclusivement localisé dans la peau des articulations des extrémités. Il effleure, dans la discussion du cas, la question d'un lien éventuel entre le tronc cérébral et les articulations.     

A Fractally Coated, 1.3 mm2 High Impedance Pacing Electrode

Minimizing the geometric surface area of pacing electrodes increases impedance and reduces the current drain during stimulation, provided that voltage (pulse-width) thresholds remain unchanged. This may be feasible by coating the electrode surface to increase the capacity of the electrode tissue interface and to diminish polarization. Ten unipolar, tined leads with a surface area of 1.3 mm² and a “fractal” coating of Iridium (Biotronik SD-V137) were implanted in the ventricle, and electrogram amplitude (unfiltered), slew-rate, pacing threshold (0.5 ms), and impedance (2.5 V; 0.5 ms) were measured by the 5311 PSA (Medtronic). On days 0, 2, 5, 10, 28, 90, 180, 360 postimplant, sensing threshold (up to 7.0 mV, measuring range 1–14 mV on day 360 only) and the strength duration curve (0.5–4.0 V; 0.03–1.5 ms; steps: 0.5 V; 0.01 ms, respectively) were determined, the minimum charge delivered per pulse (charge threshold), and the impedance were taken from pacemaker telemetry (Intermedics 294–03). Data were compared with those of an earlier series of 20 unipolar, tined TIR-leads (Biotronik) with a surface area of 10 mm² and a “fractal” coating of titanium nitride. With the model SD-V137 versus TIR, intraoperative electrogram amplitudes were 15.1 ± 6.1 versus 14.4 ± 3.9 mV(NS), slew rates 3.45 ± 1.57 versus 1.94 ± 1.06 V/s (P < 0. 05), pacing thresholds 0.16 ± 0.05 versus 0.52 ± 0.15 V (P < 0.01) and impedance measurements 1,136 ±175 versus 441 ± 73 Ω (P < 0.0001), respectively. During follow-up, sensing thresholds were the same with both leads. Differences in pulse width thresholds lost its significance on day 28 but resumed on day 360 (SD-V137: 0.08 ± 0.04 ms; TIR: 0.16 ± 0.06 ms at 2.5 V; P < 0.01). With an electrode surface of 1.3 mm², charge per pulse and impedance consistently differed from control, beingO.15 ± 0.15 versus 0. 66 ± 0. 20 μC (P < 0.001) and 1,344 ± 376 versus 538 ± 79 Ω, respectively, one year after implantation (P < 0.0001). In summary, “fractally” coated small surface electrodes do not compromise sensing; by more than doubling impedance against controls they offer pacing thresholds (mainly in terms of charge) that are significantly lower than with the reference electrode.     

Comparison of a New Lancet and a Hypodermic Needle for Skin Prick Testing

Skin prick tests with a standard allergen panel were carried out in duplicate (one on each arm) on all patients referred to an allergy out-patient clinic. A new lancet with 1-mm point length and a disposable hypodermic needle were used. Patients were randomized to lancet-needle, lancet-lancet, or needle-needle, and the skin prick tests were done by experienced or inexperienced nurses. The mean of the biggest and smallest diameters was used as a measure of the size of the wheal. Skin reactions from a total of 142 patients were included. For both lancet and needle a significant difference was noted when comparing experienced versus inexperienced investigators' reproducibility expressed as coefficient of variation. There was no significant difference in reproducibility when comparing lancet and needle results, and no significant difference in wheal size when comparing with histamine references. Surprisingly, the reactions on left arms were generally larger than those on right arms.     

Ki67 LABELLING INDEX: AN INDEPENDENT PREDICTOR OF PROGRESSION IN PROSTATE CANCER TREATED BY RADICAL PROSTATECTOMY

The clinical course of prostate cancer is highly variable and cannot satisfactorily be predicted by histological criteria alone. Both tumour cell proliferation and neuroendocrine differentiation have been suggested as additional prognostic parameters, neuroendocrine differentiation being considered to enhance tumour cell proliferation. This study investigated the prognostic value of tumour cell proliferation [Ki67 labelling index (LI), MIB 1] and neuroendocrine differentiation and their relationship to each other. One hundred and thirty-seven paraffin-embedded radical prostatectomy specimens were examined. Neuroendocrine differentiation was found in 58 per cent of cases, but was not associated with pTN stage, Gleason score, Ki67 LI, or tumour progression. Ki67 LI was not significantly associated with pTN stage or with Gleason score. High grade ( P =0·0005), advanced local stage ( P =0·0004), positive lymph nodes ( P =0·02), and high Ki67 LI ( P =0·0203) were predictors of tumour progression if univariate analysis was performed, but Cox stepwise regression showed that only advanced local stage ( P =0·0025) and Ki67 LI ( P =0·0105) were independent predictors of tumour progression, the relative risk being 3·6 and 2·5, respectively. It is concluded that Ki67 is an important prognostic marker in prostate cancer with a potential for routine application.     

Severe oral lichen planus: treatment with an aromatic retinoid (etretinate)

A double-blind study of twenty-eight patients with severe oral lichen planus treated with etretinate (75 mg daily) or a placebo for 2 months, showed that the oral retinoid had a marked beneficial effect. Nine non-responders who had received only placebo then entered an open cross-over study and they responded well to etretinate. Etretinate thus provided effective symptomatic relief for severe oral lichen planus, but side-effects were common, and six patients stopped treatment because of them.