Biomedical subjects

A Katz

Publications and source records attributed to A Katz.

At least 19 recordsLinked to original sources

PubMed2006

Proteins and dipicolinic acid released during heat shock activation of Bacillus subtilis spores probed by optical spectroscopy.

UV fluorescence and absorption spectroscopy from Bacillus subtilis spores detected proteins and dipicolinic acid (DPA) released into the supernatant after heat treatments ranging from 20 degrees to 90 degrees C. The protein and DPA concentration in the supernatant was greater with higher heat treatment temperatures, undergoing a substantial increase for T > or = 60 degrees C, and supporting the theory that spores undergo a phase transition from a glassylike to a rubberylike state at 56 degrees C. Gel electrophoresis detected several small proteins with molecular weights between 6 and 11 kDa. These proteins may be small acid-soluble spore proteins that are present in spores but break down during germination. A 30 kDa protein extracted above 60 degrees C is related to the rubber-glass phase transition.

Bacillus subtilis↗

PubMed2005

In situ determination of refractive index and size of Bacillus spores by light transmission.

Light-extinction measurements in the wavelength range of 400 to 1000 nm are performed in situ on Bacillus subtilis endospores during heat-shock-induced activation. Simultaneous information on particle size and refractive indices during activation is calculated from the transmission spectra by use of the Gaussian ray approximation of anomalous diffraction theory. During activation the refractive index of the core decreases from 1.51 to 1.39, and the size increases from 0.38 to 0.6 microm.

Bacillus subtilis↗

PubMed2005

Wireless spectroscopic compact photonic explorer for diagnostic optical imaging.

A remote, small-size spectroscopic-based device called Compact Photonics Explorer (CPE) was designed, assembled, and tested for medical and non-medical spectroscopic and imaging applications. Spatial images acquired using the spectroscopic CPE are presented. Operational principles are demonstrated for various biomedical and non-medical applications.

Colorimetry↗

PubMed2005

The feasibility of a randomised, placebo-controlled clinical trial of homeopathic treatment of depression in general practice.

UNLABELLED: Depression is common in general practice and lack of concordance is an important problem in its treatment. Homeopathy has few side effects and is generally associated with good compliance. We report a study investigating the feasibility of a trial to compare the effectiveness of homeopathy with a conventional antidepressant and placebo. OBJECTIVES: To assess the feasibility of a general practice-based clinical trial comparing the effectiveness of individualised homeopathic treatment vs Fluoxetine (Prozac) vs placebo in the treatment of major depressive episodes of moderate severity. DESIGN: Randomised, double-dummy, double-blind parallel group clinical trial. SETTING: Lower Clapton Group Practice, East London. METHOD: Patients were recruited through their general practitioners as they presented during a 9 month period. Recruitment target was 30 patients. Eligibility was confirmed by a consultant psychiatrist using standard criteria (DSM-IV) and instruments Hamilton Depression Scale (HAMD). Suicidal and psychotic patients were excluded, additional precautions against suicide were incorporated. There was a 1 week run-in period and patients showing spontaneous improvement were excluded. Homeopathic treatment was prescribed by a GP qualified in homeopathy, from a 'limited list' of 30 homeopathic medicines, with the help of decision support software. Patients were randomised to receive verum Fluoxetine and placebo homeopathy, or verum homeopathy and placebo Fluoxetine, or placebo homeopathy and placebo Fluoxetine. Treatment duration was 12 weeks. The outcomes were: adverse drug reactions, clinical global impression (CGI); HAMD; mini international psychiatric Interview; Pittsburgh sleep quality index; Side-effects checklist; Short Form 12; treatment credibility questionnaire; work and social disability scale. The primary outcome measures were HAMD and CGI. RESULTS: A recruitment calculation indicated that over 230 suitable patients would be expected to attend the practice during the recruitment phase. Thirty one patients were referred for possible inclusion in the trial by their GPs. Twenty three met the entry criteria, 11 were randomised and 6 completed the study. Of the completers, one received homeopathy, 2 placebo and 3 Fluoxetine. CONCLUSIONS: A trial of this design in general practice is not feasible, because of recruitment difficulties, many of them linked to patient preference. Different approaches are required to recruit adequate patient numbers to trials of this sort.

Adult↗

PubMed2004

Interaction of FIE, a polycomb protein, with pRb: a possible mechanism regulating endosperm development.

Inactivation of the Arabidopsis protein FERTILIZATION INDEPENDENT ENDOSPERM (FIE) induces division of the central cell of the embryo sac, leading to endosperm development in the absence of fertilization. The mechanism whereby FIE regulates this process is unknown. We postulated that activation of central cell division in fie mutant plants might involve the retinoblastoma protein (pRb), a cell cycle regulatory element. Pull-down and surface plasmon resonance assays demonstrated that FIE interacts in-vitro with the pRb homologues from Arabidopsis (AtRb), maize (ZmRb) and human (HuRb). The interaction of FIE with ZmRB and HuRb in the yeast two-hybrid system supports the possibility that a FIE-pRb interaction may occur also in planta. Mutational analysis showed that this interaction does not occur via the LxCxE motif of the FIE protein nor via the pocket B domain of pRb. These results suggest that FIE may inhibit premature division of the central cell of the embryo sac, at least partly, through interaction with pRb, and suppression of pRb-regulated genes.

Arabidopsis↗

PubMed2004

Acute mastoiditis in infancy: the Soroka experience: 1990-2000.

UNLABELLED: Acute mastoiditis (AM) is an uncommon but serious complication of acute otitis media (AOM). In the pre-antibiotic era, AM was seen more frequently than it is today, but it was rare in infants. However, in the last two decades an increase in the incidence of AM in infancy has been reported in the literature. During the years 1990-2002, we treated 113 patients with 128 episodes of AM; of them, 24 were infants (median age 6 months; 18 males) who suffered from 26 episodes of AM. Twenty developed AM as a complication of their first episode of AOM. One of the four infants with a prior history of AOM suffered from common variable immunodeficiency. A significant increase in the incidence of AM in infants was recorded during the study period (P = 0.01). The most common presenting clinical signs were post-auricular swelling and fever >38 degrees C (77% and 77%, respectively, of all patients). Seventeen episodes of AM were not treated with prior antibiotics. Tympanocentesis was performed in all episodes of AM. Middle ear fluid culture was positive in 17 (65%) of the 26 AM episodes. The most common pathogens cultured were Streptococcus pneumoniae (10 infants, 58% of all pathogens, 3/10 intermediately susceptible to penicillin) followed by Streptococcus pyogenes (4, 23%), non-typable H. influenzae (2, 12%) and S. aureus (1, 6%). Temporal bone CT showed bone destruction in 14 patients; 3 infants had subperiosteal abscesses and 3 lateral sinus thrombosis. Ten infants underwent mastoid surgery due to non-resolution of symptoms and signs with antibiotic therapy. Eight underwent cortical mastoidectomy with two patients undergoing ventilation tube introduction only. The remainder of the infants healed with conservative treatment. CONCLUSIONS: (1) A significant increase in the incidence of AM in infants was recorded over the last decade, though a specific reason for this trend remains uncertain; (2) Most of the cases of AM followed the infant's initial AOM episode, and most of the infants had not received prior antibiotic therapy; (3) The clinical signs and symptoms of AM were more severe in infants than in older patients; (4) While S. pneumonia was the most common pathogen isolated in middle ear fluid cultures, the involvement of S. pyogenes in AM was higher than that reported in AOM.

Abscess↗

PubMed2004

The anaesthetic management of patients with congenital insensitivity to pain with anhidrosis.

BACKGROUND: Congenital insensitivity to pain with anhidrosis (CIPA, or hereditary sensory and autonomic neuropathy type IV) is a rare, autosomal recessive disease, related to a mutation in the TrkA gene, characterized by inability to sweat, insensitivity to pain and recurrent episodes of hyperpyrexia. There are two Bedouin tribes in Israel with different mutations of the TrkA gene: one in the southern region and the other in the northern region. The Soroka University Medical Center is the referral centre for the entire southern region of Israel. One in 4500 anaesthesia cases involves a patient with CIPA. METHODS: We reviewed 40 anaesthesia records of 20 patients with CIPA for anaesthetic technique and incidence of side-effects. RESULTS: Sixteen patients developed complications in the immediate perioperative period: mild hypothermia in one patient and cardiovascular events in 15 others with one case of cardiac arrest. These complications were unrelated to the anaesthetic drug administered. There were no events of hyperthermia or postoperative nausea. CONCLUSIONS: Cardiovascular complications following anaesthesia are common in patients with the southern Israel variant of CIPA. Hyperthermia, previously recognized as a major concern in patients with congenital insensitivity to pain with anhydrous, was not seen in our patients. We conclude that cardiovascular involvement is frequently encountered in CIPA patients following anaesthesia and is the major concern in their anaesthetic management.

Adolescent↗

PubMed2004

A standard for radiopacity of root-end (retrograde) filling materials is urgently needed.

AIM: To assess the radiopacity of materials used, or recommended for use, as apical root-end (retrograde) fillings. METHODOLOGY: The radiopacity of 14 materials falling into the category of root-end filling materials was measured in equivalent millimetres of aluminium (mm Al) using a new computerized method. These included temporary or intermediate sealing materials; composite, compomer and GIC filling materials; EBA-derived cements; amalgam, etc. Gutta-percha cone material was added as a control. Samples of 1 mm thickness were radiographed on periapical film alongside an aluminium step wedge calibrated in millimetres, and the opacity of the materials, in greyscale or pseudo-colour, was compared with the equivalent step. RESULTS: The radiopacity ranged from 1.75 mm Al to >10 mm Al. The lower range appears insufficient for routine clinical detection when it is compared with the minimal requirement for intracanal fillings. CONCLUSIONS: Because of the proliferation of root-end filling materials with a broad range of radiopacity, an international standard stipulating the required minimal radiopacity, as well as other properties, is needed urgently. It should be based on in vitro results and on large-scale clinical radiographic surveys.

Contrast Media↗

PubMed2003

Quality-of-life benefits and evidence of antitumour activity for patients with brain metastases treated with gefitinib.

Brain metastases are a common complication of non-small-cell lung cancer (NSCLC). The role of chemotherapy in the treatment of brain metastases has not been clearly defined. Emerging case reports of patients with recurrent NSCLC treated as part of the Expanded Access Programme reveal that gefitinib ("Iressa", ZD1839) has clinical activity in some patients with brain metastases. Here, we describe a number of case studies documenting the response of patients with brain metastases to treatment with gefitinib. Many of these patients had quality-of-life benefits with improvement of neurological and systemic symptoms; some had a partial response of their brain metastases and even complete responses have been seen in a few patients. One case report also describes a durable long-term response with concurrent treatment with gefitinib and radiotherapy. Such results call for larger trials designed to evaluate and define the role of gefitinib in the treatment of brain metastases in NSCLC patients, either as a single agent or in combination with radiation therapy.

Antineoplastic Agents↗

PubMed2003

A combined radiographic and computerized scanning method to evaluate remaining dentine thickness in mandibular incisors after various intracanal procedures.

AIM: To develop a computerized model to evaluate remaining dentine thickness after various intracanal procedures. METHODOLOGY: A three-step model was developed, in which injection of radiopaque solution into the root-canal space of 20 extracted mandibular incisors, exposure of periapical radiographs from two directions, and computerized scanning and printing of the image were combined. Following root-canal preparation and preparation of post space, evaluation of remaining dentine thickness was completed using appropriate software. RESULTS: Remaining dentine thickness was significantly affected (P < 0.01) by place (mesial-distal more than buccal-lingual), stage (root-canal preparation more than post space) and location (coronal more than middle and apical). CONCLUSIONS: This in vitro study confirmed that in an oval root-canal space, the mesial and distal aspects are mainly affected by intraradicular procedures. The three-step method is a useful tool to evaluate root-canal instrumentation as the root or tooth can remain intact during the procedure.

Contrast Media↗

PubMed2003

Aorta and skin tissues welded by near-infrared Cr4+:YAG laser.

OBJECTIVE: The aim of our study was to explore the wavelength dependence of welding efficacy. Ex vivo samples of human and porcine aorta and skin tissues were investigated using a tunable Cr(4+):yttrium aluminum garnet (YAG) laser. BACKGROUND DATA: Tissue welding is possible using laser light in the NIR spectral range. Collagen bonding in the tissue induced by thermal, photothermal, and photochemical reactions-or a combination of all of these-is thought to be responsible for tissue welding. Laser tissue welding (LTW) has gained success in the laboratory using animal models. Transition from laboratory to clinical application requires the optimization of welding parameters. MATERIALS AND METHODS: A near-infrared (NIR) Cr(4+):YAG laser was used to weld ex vivo samples of human and porcine aorta and skin at wavelengths from 1430 to 1470 nm. Welding efficacy was monitored by measuring the tensile strength of the welded tissue and the extent of collateral tissue damage. Tensile strengths were measured using a digital force gauge. Changes in tissue morphology were evaluated using optical and scanning electron microscope (SEM). Fluorescence imaging of the welded areas was also used to evaluate molecular changes following tissue welding. RESULTS: Full-thickness tissue bonding was observed with porcine aorta samples. No collateral damage of the aorta samples was observed. Tissue denaturation was observed with human aorta, human skin, and porcine skin samples. The optimum tensile strength for porcine and human aorta was 1.33 +/- 0.15 and 1.13 +/- 0.27 kg/cm2, respectively, at 1460 nm, while that for porcine and human skin was 0.94 +/- 0.15 and 1.05 +/- 0.19 kg/cm2, respectively, achieved at 1455 nm. The weld strength as a function of wavelength demonstrated a correlation with the absorption spectrum of water. Fluorescence imaging of welded aorta and skin demonstrated no significant changes in collagen and elastin emission at the weld site. CONCLUSION: The observation that welding strength as a function of wavelength follows the absorption bands of water suggests that absorption of light by water plays a significant role in laser tissue welding.

Animals↗

PubMed2003

Variation in the DCP1 gene, encoding the angiotensin converting enzyme ACE, is not associated with increased susceptibility to Alzheimer's disease.

OBJECTIVES: To attempt to replicate previous reports that polymorphic variation in the DCP1 gene causes increased susceptibility to the development of Alzheimer's disease, either on its own or in interaction with the effects of the gene for apolipoprotein E (APOE). METHOD: Subjects older than 65 years of age consisting of 81 dementia patients diagnosed as having possible or probable Alzheimer's disease and 68 controls were obtained from Camden, Islington and Harlow psychiatric services. Subjects were genotyped for APOE alleles e2, e3 and e4, and the common insertion/deletion polymorphisms for DCP1* I/D were genotyped. RESULTS: There was no statistically significant difference in the frequency of the DCP1* insertion/deletion alleles between the cases and controls (X2 =0.04, 1 degree of freedom, not significant). When subjects were subdivided according to whether they possessed at least one copy of the APOE e4 allele, there were still no differences in DCP1 allele frequencies between cases and controls. CONCLUSIONS: Further research is needed to elucidate any role that the DCP1 polymorphism may play in relation to Alzheimer's disease. Previous studies may be false positive, or inconsistency in replication may be due to heterogeneity.

Aged↗

PubMed2003

A novel retro-inverso gonadotropin-releasing hormone (GnRH) immunogen elicits antibodies that neutralize the activity of native GnRH.

GnRH vaccines have been successfully used for the inhibition of gonadotropin secretion and gonadal function. As an alternative to native GnRH, retro-inverso (RI) GnRH might be an improved immunogen. The RI peptides are composed of D-amino acids assembled in the reverse order (C to N terminus) in relation to the parent L peptide. These peptides are immunogenic and can produce high titers of antibodies that bind the parent peptide with high affinity and specificity. We show that RI-GnRH peptides conjugated to ovalbumin as well as unconjugated RI-GnRH elicit high titers of anti-GnRH antibodies in rabbits and mice. Antibodies were affinity purified and shown by ELISA to be selective for mammalian GnRH compared with GnRH II and [Gln(8)]GnRH. The binding kinetics of antibody-peptide interactions was determined using biosensor technology (BIACORE). The purified anti-GnRH antibodies inhibited GnRH-stimulated signal transduction in COS-1 cells expressing the human GnRH receptor. Immunization of mice with unconjugated and conjugated RI-GnRH peptide, in the absence of complete Freund's adjuvant, produced antisera that cross-reacted with mammalian GnRH. As RI peptides are resistant to cleavage by proteolytic enzymes, they are potentially orally active. The ability of RI-GnRH peptides to produce antibodies to GnRH without conjugation and without Freund's complete adjuvant constitutes a novel vaccine with improved properties of potential application in animal management and sex hormone-dependent cancers.

Animals↗

PubMed2002

Noninvasive native fluorescence imaging of head and neck tumors.

Fluorescence images were acquired from ex vivo head and neck tumor specimens. The excitation and emission wavelength combinations were selected to image emission from native tissue fluorophores (collagen, tryptophan, elastin and nicotinamide adenine dinucleotide). Two dimensional intensity ratio maps were generated from the fluorescence images and compared to histology images. The ratio maps accurately distinguished the regions of tumor from normal tissue in the specimens. Additional features, such as collagen capsules, blood vessels, mucus glands and muscles were evident in the fluorescence images.

Carcinoma, Papillary↗

PubMed2001

Adenine nucleotide translocator isoforms 1 and 2 are differently distributed in the mitochondrial inner membrane and have distinct affinities to cyclophilin D.

Different isoforms of the adenine nucleotide translocase (ANT) are expressed in a tissue-specific manner. It was assumed that ANT-1 and ANT-2 co-exist in every single mitochondrion and might be differently distributed within the membrane structures that constitute the peripheral inner membrane or the crista membrane. To discriminate between ANT originating from peripheral or from cristal inner membranes we made use of the fact that complexes between porin, the outer-membrane pore protein, and the ANT can be generated. Such complexes between porin and the ANT in the peripheral inner membrane were induced in rat heart mitochondria and isolated from rat brain and kidney. Using ANT-isotype-specific antibodies and sequence analysis of the N-terminal end, it was discovered that the peripheral inner membrane contained ANT-1 and ANT-2, whereas the cristal membrane contained exclusively ANT-2. Cyclophilin was co-purified with the porin-ANT complexes, whereas it was absent in the crista-derived ANT. This suggested that ANT-1 might have a higher affinity for cyclophilin. This specific intra-mitochondrial distribution of the two ANT isotypes and cyclophilin D suggests specific functions of the peripheral and crista-forming parts of the inner membrane and the two ANT isotypes therein.

Animals↗

PubMed2001

A novel mammalian receptor for the evolutionarily conserved type II GnRH.

Mammalian gonadotropin-releasing hormone (GnRH I: pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) stimulates pituitary gonadotropin secretion, which in turn stimulates the gonads. Whereas a hypothalamic form of GnRH of variable structure (designated type I) had been shown to regulate reproduction through a cognate type I receptor, it has recently become evident that most vertebrates have one or two other forms of GnRH. One of these, designated type II GnRH (GnRH II: pGlu-His-Ser-His-Gly-Trp-Tyr-Pro-Gly-NH2), is conserved from fish to man and is widely distributed in the brain, suggesting important neuromodulatory functions such as regulating K+ channels and stimulating sexual arousal. We now report the cloning of a type II GnRH receptor from marmoset cDNA. The receptor has only 41% identity with the type I receptor and, unlike the type I receptor, has a carboxyl-terminal tail. The receptor is highly selective for GnRH II. As with the type I receptor, it couples to G(alpha)q/11 and also activates extracellular signal-regulated kinase (ERK1/2) but differs in activating p38 mitogen activated protein (MAP) kinase. The type II receptor is more widely distributed than the type I receptor and is expressed throughout the brain, including areas associated with sexual arousal, and in diverse non-neural and reproductive tissues, suggesting a variety of functions. Surprisingly, the type II receptor is expressed in the majority of gonadotropes. The presence of two GnRH receptors in gonadotropes, together with the differences in their signaling, suggests different roles in gonadotrope functioning.

Amino Acid Sequence↗

PubMed2001

Heliox improves gas exchange during high-frequency ventilation in a pediatric model of acute lung injury.

Because heliox has a lower density as compared with air, we postulated that heliox would improve gas exchange during high-frequency oscillatory ventilation (HFOV) in a model of acute lung injury. In a prospective, cross-over trial, we studied 11 piglets with acute lung injury created by saline lavage. With initial conditions of permissive hypercapnia (Pa(CO(2)) 55-80 mm Hg), each piglet underwent HFOV with a fixed mean airway pressure, pressure oscillation, and ventilatory frequency. The following gas mixtures were used: oxygen-enriched air (60% O(2)/40% N(2)) and heliox (60% O(2)/ 40% He and 40% O(2)/60% He). Compared with oxygen-enriched air, the 40% and 60% helium gas mixtures reduced Pa(CO(2)) by an average of 10.5 and 20.3 mm Hg, respectively. A modest improvement in oxygenation was seen with the 40% helium mixture. We conclude that heliox significantly improves carbon dioxide elimination and modestly improves oxygenation during HFOV in a model of acute lung injury. On the basis of test lung data and plethysmography measurements, we also conclude that heliox improves carbon dioxide elimination primarily through increased tidal volume delivery. Although heliox improved gas exchange during HFOV in our model, increased tidal volume delivery may limit clinical applicability.

Animals↗

PubMed2001

A new glycogen synthase activity ratio in skeletal muscle: effects of exercise and insulin.

It was recently reported that MnSO4 stimulates glycogen synthase-dependent glucose transfer from UDPglucose into trichloroacetic acid precipitable endogenous glycoproteins (GSMn(T)) in human muscle extracts. To determine the physiologic significance of this reaction, we compared a new GS activity ratio, GSMn(T)/GSH(E) (where GSH(E) represents the usual glucose transfer to ethanol precipitable exogenous glycogen by GS at 7.2 mM glucose 6-phosphate), with the generally used GSL(E)/GSH(E) ratio (where GSL(E) represents glucose transfer at 0.17 mM glucose 6-P concentration). Biopsies were obtained from the quadriceps femoris muscle of healthy subjects at rest, after 40 min of bicycle exercise at approximately 65% of maximal oxygen uptake and after isometric contraction at 2/3 maximal force to fatigue (approximately 1 min). GSMn(T)/GSH(E) increased from 0.012+/-0.002 at rest to 0.054+/-0.008 (P<0.01) after 40 min of bicycle exercise and the increase in GSMn(T) activity was strongly related to the decrease in endogenous glycogen (i.e.. increase in short-chain endogenous glycoproteins) (r=0.90; P<0.05). On the other hand, GSL(E)/GSH(E) did not change significantly after bicycle exercise (rest = 0.49+/-0.04; exercise = 0.58+/-0.08, P>0.05). GSMn(T)/GSH(E) increased from 0.010+/-0.001 at rest to 0.016+/-0.002 (P<0.05) after isometric exercise, whereas GSL(E)/GSH(E) decreased from 0.27+/-0.04 to 0.20+/-0.02 (P<0.05) under corresponding conditions. Last, insulin, which stimulates glycogen synthesis, also increased GSMn(T)/GSH(E) (1.8-fold, P<0.05), as well as GSL(E)/GSH(E) (1.4-fold, P<0.05), in isolated rat soleus muscle. These data indicate that GSMn(T)/GSH(E) is influenced by endogenous substrate availability and covalent modification. Therefore, GSMn(T)/GSH(E) ratio may prove to be a useful alternative to other GS activity ratios that only reflect changes in the phosphorylation state of GS.

Exercise↗