Multiple origins and circular structures in replicating T5 bacteriophage DNA.

Replicating T5 phage DNA was gently isolated using NaI density gradient centrifugation and examined by electron microscopy. At the beginning of phage DNA synthesis, linear unit-length T5 DNA molecules containing from one to four replicating "eye-loops" were consistently observed. Replication in these molecules was found to proceed bidirectionally from multiple, internal origins. A primary origin of replication is located near the center of the T5 genome, which does not coincide with the location of any of the nicks (single-strand breaks) found in mature T5 DNA. The initiation of replication at the various origins within an individual molecule does not appear to follow any definite temporal sequence. At later times in the infection, we have observed a significant number of circular T5 DNA molecules-both replicating and nonreplicating-whose average circumference is approximately the length of mature T5 DNA minus the terminal redundancy. The replicating circular molecules appear to be either in a theta configuration, a sigma configuration with the tails all being less than the length of the circle, or a combination of theta and sigma forms.     

γ-Hydroxybutyrate uptake by rat brain striatal slices

-Hydroxybutyrate uptake by rat brain striatal slices was studied. The uptake was saturable with aK _m of 702±107.10^–6M. -Hydroxybutyrate uptake was sodium dependent and inhibited by the omission of potassium. In addition, the effect of ouabain suggests that the transport is dependent on a cation gradient. Several analogues of -hydroxybutyrate inhibit the transport system. GABA has no significant effect. This energy and cation dependent transport system is in favor of a transmitter or modulator role of -hydroxybutyrate in the rat brain striatum.     

Can Zipf's law be adapted to normalize microarrays?

Background  

Normalization is the process of removing non-biological sources of variation between array experiments. Recent investigations of data in gene expression databases for varying organisms and tissues have shown that the majority of expressed genes exhibit a power-law distribution with an exponent close to -1 (i.e. obey Zipf's law). Based on the observation that our single channel and two channel microarray data sets also followed a power-law distribution, we were motivated to develop a normalization method based on this law, and examine how it compares with existing published techniques. A computationally simple and intuitively appealing technique based on this observation is presented.     

Leishmania amazonensis: early proteinase activities during promastigote-amastigote differentiation in vitro

Leishmania proteinase activity is known as parasite differentiation marker, and has been considered relevant for leishmanial survival and virulence. These properties suggest that Leishmania proteinases can be promising targets for development of anti-leishmania drugs. Here, we analyze the activities of four proteinases during the early phase of the Leishmania amazonensis promastigotes differentiation into amastigotes induced by heat shock. We have examined activities of cysteine-, metallo-, serine-, and aspartic-proteinase by hydrolysis of specific chromogenic substrates at pH 5.0 and at the optimal pH for each enzyme. Our results show that metallo-, serine-, and aspartic-proteinases activities were down-regulated during the shock-induced transformation of promastigotes into amastigotes. In contrast, cysteine-proteinase activity increased concomitantly with the promastigote differentiation. Immunocytochemical localization using two anti-cysteine-proteinase monospecific rabbit antibodies detected the enzyme in several cell compartments of both parasite stages. Our results show different proteinase activity modulation and expression during the early phases of the shock-induced parasite transformation.     

Hyaluronan-CD44 interaction with Rac1-dependent protein kinase N-gamma promotes phospholipase Cgamma1 activation, Ca(2+) signaling, and cortactin-cytoskeleton function leading to keratinocyte adhesion and differentiation

In this study we have investigated hyaluronan (HA)-CD44 interaction with protein kinase N-gamma (PKNgamma), a small GTPase (Rac1)-activated serine/threonine kinase in human keratinocytes. By using a variety of biochemical and molecular biological techniques, we have determined that CD44 and PKNgamma kinase (molecular mass approximately 120 kDa) are physically linked in vivo. The binding of HA to keratinocytes promotes PKNgamma kinase recruitment into a complex with CD44 and subsequently stimulates Rac1-mediated PKNgamma kinase activity. The Rac1-activated PKNgamma in turn increases threonine (but not serine) phosphorylation of phospholipase C (PLC) gamma1 and up-regulates PLCgamma1 activity leading to the onset of intracellular Ca(2+) mobilization. HA/CD44-activated Rac1-PKNgamma also phosphorylates the cytoskeletal protein, cortactin, at serine/threonine residues. The phosphorylation of cortactin by Rac1-PKNgamma attenuates its ability to cross-link filamentous actin in vitro. Further analyses indicate that the N-terminal antiparallel coiled-coil (ACC) domains of PKNgamma interact directly with Rac1 in a GTP-dependent manner. The binding of HA to CD44 induces PKNgamma association with endogenous Rac1 and its activity in keratinocytes. Transfection of keratinocytes with PKNgamma-ACCcDNA reduces HA-mediated recruitment of endogenous Rac1 to PKNgamma and blocks PKNgamma activity. These findings suggest that the PKNgamma-ACC fragment acts as a potent competitive inhibitor of endogenous Rac1 binding to PKNgamma in vivo. Most important, the PKNgamma-ACC fragment functions as a strong dominant-negative mutant that effectively inhibits HA/CD44-mediated PKNgamma phosphorylation of PLCgamma1 and cortactin as well as keratinocyte signaling (e.g. Ca(2+) mobilization and cortactin-actin binding) and cellular functioning (e.g. cell-cell adhesion and differentiation). Taken together, these findings strongly suggest that hyaluronan-CD44 interaction with Rac1-PKNgamma plays a pivotal role in PLCgamma1-regulated Ca(2+) signaling and cortactin-cytoskeleton function required for keratinocyte cell-cell adhesion and differentiation.     

Health and psychosocial status of patients with turner syndrome after transition to adulthood: the Belgian experience

BACKGROUND: Most girls with Turner syndrome (TS) are intensively followed by paediatricians, but are lost to follow-up when they reach adulthood. To gain insight into the adult medical and psychosocial situation, we performed a survey in young adult TS patients. PATIENTS AND METHODS: A questionnaire concerning current health status, education, occupation and living situation was sent to 160 young adult TS women, all treated during childhood with GH and oestrogen if needed. RESULTS: We received 102 completed questionnaires. Mean +/- SD age at reception of the questionnaire was 23.4 +/- 3.3 years, height 153.3 +/- 5.2 cm, body mass index 23.7 +/- 4.9 kg/m(2). Age and auxological parameters were comparable between responders and non-responders. Thirteen (12.7%) responders were not under regular medical care; 15 (14.7%) were seen by a general practitioner, while 28 (27.4%) needed several specialists. Forty-one (40.2%) patients reported health problems. The most frequently reported problem was hypertension (10.7%), followed by hypothyroidism (5.8%) and back problems (4.9%). Twenty-four (23.5%) of the 41 patients were taking medication for the indicated health problems. Twenty-six (25.5%) women had undergone spontaneous puberty; 16 of them reported spontaneous menstruations while 10 received oestrogen replacement therapy. Of the 76 women with induced puberty, 11 (14.5%) were not taking any oestrogen anymore. Compared with the general population, more TS women attended university and more obtained higher education. Forty-six women (45.1%) were working full-time, 7 (6.9%) were unemployed, and 4 (3.9%) received an allocation. Seventy (68.6%) patients were still living with their parents, while 18 (17.6%) were living together or married, and 14 (13.7%) were living alone. CONCLUSIONS: The transition of adolescents with TS to adult medical care is not optimal in Belgium. Although 40.2% of these young women reported health problems, 12.7% did not consult any physician. Many TS women did not take oestrogen replacement therapy. A specialized multidisciplinary approach for adults with TS is needed in order to optimize health and psychosocial status in these women.