Kurze Mitteilungen

Zusammenfassung Ein Paar Türkentauben brütete vom 29. 1. bis 15. 2. 1966 auf einem Straßenbaum in Berlin-Tempelhof. Es wurde nur ein Ei gelegt. Nach 17 Tagen schlüpfte das gelbbedaunte Junge. Es ist dann kurz danach, wahrscheinlich beim Umherkriechen auf dem Nestrand, erfroren. Die Umstände, unter denen die Brut erfolgte, waren äußerst ungünstig. Die Temperatur lag seit dem 7. 2. 1966 dauernd unter Null (–9 und –13 Grad). Die brütende Taube hatte von Anfang an auf dem Nestrand brüten müssen, da die Mulde schon vor der Eiablage völlig mit Schnee bedeckt war. Der brütende Vogel war mehrere Tage und Nächte von einem hohen Schneewall umgeben, der sich auf dem Nest gebildet hatte. Dieses Nest wurde von Mai 1964 an viermal von einem Türkentaubenpaar zum Brüten benutzt. Es wird vermutet, daß zum mindesten der eine Partner, der Tauber, während der ganzen Zeit derselbe geblieben ist.     

Use of hospital services by homeless families in an inner London health district.

Over the past decade the number of families in London who were considered officially to be homeless appreciably increased. In response to this many families have been given temporary accommodation, usually in bed and breakfast hotels, while awaiting permanent rehousing. About 200 of the roughly 600 hotels in London that provide such accommodation are located in the area of the former Paddington and North Kensington Health Authority, now part of Parkside Health Authority. The use made by the homeless population of hospital services was studied by finding out the numbers of inpatients admitted to hospital and the numbers presenting to the walk in paediatric clinic and the casualty department at one hospital. These figures were compared with those for local residents and the overall workload. The bed and breakfast population were high users of inpatient beds, the casualty department, and the paediatric clinic. Overall, about one tenth of the beds were used by these people. The health authority receives no additional funding for this group of patients. Further research is needed to find out if the high use of hospital services made by these patients reflects their increased morbidity or their inability to obtain primary care services.     

Evaluation of the cervical cytology screening programme in an inner city health district.

District health authorities have been instructed to operate a cervical cytology call and recall screening programme using the age-sex registers held by family practitioner committees. A detailed evaluation of implementation in an inner London district showed that 477 out of 687 (69%) invitation letters sent to women by the family practitioner committee were either inaccurate or inappropriate: almost half of the recorded addresses were incorrect and a further fifth of the women were not eligible for a test. Overall, 90 women had a smear, which is only 13% of the total but 43% of those found to be eligible. The findings did not differ significantly with age. The findings have major implications not only for the effectiveness of call and recall for screening for cervical cancer but also for the future development of screening for breast cancer in such areas.     

A simple and reliable turbidimetric and kinetic assay for alpha-amylase that is readily applied to culture supernatants and cell extracts

Summary A simple, reliable and sensitive assay for alpha-amylase activity is reported, together with its theoretical derivation, that overcomes many of the problems encountered with other assays, especially when attempting to assay alpha-amylase activity in crude cell extracts or culture supernatants. The method relies on the reduction in turbidity that occurs upon digestion of a starch suspension with alpha-amylase. The initial rate of decrease in turbidity is shown to be proportional to a wide range of enzyme concentrations, permitting a rapid spectrophotometric and kinetic determination of alpha-amylase activity.     

Growing tobacco cells respond to rapid medium changes with a transient increase in localized Ca2+ activity

Summary A suspension of tobacco cells,Nicotiana tabacum L. BY-2, was subjected to a rapid change of medium, resulting in disturbance of growth. A subpopulation of growing cells responded to such a nutritional signal by establishing a transient, localized Ca²⁺ accumulation, as judged by chlorotetracycline fluorescence. Residing near or at the plasma membrane, this initial Ca²⁺ signal began to relax after 1 h to a value presumably corresponding to an equilibrium Ca²⁺ level. This response was susceptible to treatment with brefeldin A, an agent impacting vesicular traffic, as indicated by a further increase in fluorescence. By contrast, undisturbed growing and non-growing cells did not display a Ca²⁺ response, regardless of the presence of brefeldin A.     

Membrane receptors for estrogen,progesterone, and testosterone in the rat brain: Fantasy or reality

Summary 1. There are numerous circumstantial evidence supporting the concept that steroid hormones control cellular function by means other than the nuclear receptor steroid binding mechanism. It is the intent of this report to present evidence indicating that steroids bind to specific sites in neuronal membranes.2. Some of the criteria to define steroid membrane receptors using steroid-BSA conjugates that can be radioiodinated to desired specific activity have been fulfilled for each of the three sex steroids using crude synaptosomal membrane preparations (P2 fractions) from the CNS of female and male rats. Ligand binding for each of the three steroids indicate high-affinity and high-capacity sites with distinct brain selectivity and stereospecificity. For example, 17-E-6-[¹²⁵I]BSA binds hypothalamic P2 fractions (HYP-P2) with an estimatedK _d of about 3±0.7 nM (X ± SE;n=3), whereas the cerebellum P2 (CB-P2) fractions bind the ligand with aK _d of 34±7 nM and, aB _max of 3 and 42 pmol/mg protein, respectively. Estrogen and testosterone binding fit best a one-single site, while progesterone binding sites can be best represented by a two-binding site, one high-affinity (K _d=1–2 nM) and one low affinity (K _d=62 nM), in CB-P2 fractions from intact adult female rat brain. Kinetics studies for T-3-[¹²⁵I]BSA indicate that the estimatedK _d of 30±2 nM for the olfactory bulb P2 fractions (OB-P2) from male rats is in good agreement withK _d values computed from Scatchard-derived data using the LIGAND algorithm.3. 17-E-6-[¹²⁵I]BSA binding sites are stereospecific and appears to be present as early as 5 days of age in both the OB- and the CB-P2 fractions without changes during development. In contrast, P-6-[¹²⁵I]BSA binding sites are practically absent during days 5 and 12 and appear by day 22.4. Finally, membrane receptor molecules for estrogen and progesterone have been isolated and purified by affinity chromatography and characterized by PAGE and Western blot. Microsequencing of one of the membrane estrogen binding proteins indicates that the high-affinity site corresponds to the OSCP subunit of the proton ATP synthase.5. It remains to be determined if P and T also bind to this complex enzyme or if they bind to other subunits of the family of proton ATPases. Overall the data indicate that steroid hormones conjugated to BSA are important tools to study the reality of membrane steroid receptors.     

Short-term aluminium uptake by tobacco cells: Growth dependence and evidence for internalization in a discrete peripheral region

Short-term uptake and initial localization of aluminium (Al) were investigated in cultured cells of Nicotiana tabacum L. cv. BY-2. Graphite furnace atomic absorption spectrometry and an in vivo Al-sensitive fluorometric assay, employing morin, yielded similar results in all experiments. Aluminium uptake was critically dependent on cell growth. As opposed to negligible uptake in stationary-phase cells, Al uptake (20 μ M AlCl₃, pH 4.5, 23°C) by actively growing cells was detectable within 5 min, with an initial rate of 16 nmol Al (10⁶ cells)⁻¹ h⁻¹. Increased CaCl₂ levels (up to 20 m M ), low temperature (4°C), and pre-chelation of Al to citrate greatly reduced Al uptake (by 75–90%). A pH-associated permeabilization of cells at pH 4.5, as monitored by trypan blue, was observed in some growing cells. Although permeability to trypan blue was not a requirement for Al uptake, enhanced membrane permeability at pH 4.5, relative to pH 5.6, may contribute to Al uptake. Aluminium was observed to localize mainly in a pronounced and discrete fluorescent zone at the cell periphery (2–30 μm wide), presumably in the cortical cytosol and/or the adjoining plasma membrane section, although the possibility cannot be excluded that some Al resided in the cell wall apposing this discrete region. However, as judged by the Al-morin assay, there were no detectable Al levels in the remaining, larger portion of the cell wall. The potential of the Al-morin method in Al toxicity studies is illustrated.     

Evaluation of hydroxyl radical-scavenging property of garlic

While antibiotics are broadly used in dental and medical therapy, little attention has been directed towards the potential toxic side effects of antibiotics on tissue regeneration. Here we examined the effect of a quinolone antibiotic, pefloxacin (Rhone Poulenc) on rat parotid gland responses to chronic isoproterenol treatment. Groups of rats received injections of isoproterenol to induce glandular growth, saline (controls), pefloxacin, or isoproterenol and pefloxacin in combination. Parotid gland weight decreased significantly after pefloxacin treatment for 7 days as well as inhibiting glandular enlargement provoked by isoproterenol. The same trend was observed for the rates of DNA synthesis, with the incorporation of [³H]-thymidine in isoproterenol/pefloxacin-treated rats reduced to 49% of isoproterenol treatment alone levels. Saline-treated animals were 42% of the rate of [³H]-thymidine incorporation into DNA observed in isoproterenol treated rats. While isoproterenol treatment increased steady-state mRNA levels for fos, jun, myc, src, c-erbB-2, ras and topo II, inclusion of pefloxacin with the isoproterenol regimen blocked these increases. Pefloxacin treatment by itself did not alter proto-oncogene mRNA levels in the parotid gland. Glandular amylase activity was decreased in the pefloxacin treated group, while the combination of isoproterenol with pefloxacin did not decrease glandular amylase levels to the extent of that observed with -agonist treatment alone. In acute experiments, pefloxacin significantly decreased the volume of saliva secreted by the parotid gland. These results suggest that quinolone-based antibiotics disturb the secretory function of the parotid gland and can inhibit cell proliferation and regeneration. (Mol Cell Biochem 165: 55–63, 1996)