The pharmaceutical stability of trastuzumab after short-term storage at room temperature assessed by analytical techniques and tumour imaging by microSPECT/CT.

We report the pharmaceutical stability of trastuzumab stored for a short time (12 h) at room temperature (RT; 20-25 °C) compared to trastuzumab stored at 2-8 °C. The physicochemical properties were evaluated by UV-visible and FTIR spectroscopy, SDS-PAGE and size-exclusion HPLC (SE-HPLC). Trastuzumab was reacted with benzylisothiocyanate diethylenetriaminepentaacetic acid (BzDTPA) to complex 111In. The HER2-binding affinity of 111In-BzDTPA-trastuzumab synthesised from trastuzumab stored at RT or at 2-8 °C was measured using HER2-positive SK-Br-3 human breast cancer (BC) cells. The tumour and normal tissue uptake of 111In-BzDTPA-trastuzumab was studied by microSPECT/CT imaging and biodistribution studies in CD1 athymic mice with s.c. HER2-positive SK-Ov-3 human ovarian cancer xenografts. There were no differences in λmax or molar absorptivity (ε) values in the UV-visible spectra of trastuzumab stored at RT or at 2-8 °C. FTIR spectroscopy suggested no differences in secondary structure. SDS-PAGE revealed protein bands corresponding to the expected molecular weights. SE-HPLC showed identical properties for trastuzumab stored at RT or at 2-8 °C. The dissociation constant (Kd) for binding of 111In-BzDTPA-trastuzumab to HER2 on SK-Br-3 cells (2.2-4.4 nM) was not significantly different when the radioimmunoconjugates were synthesised from trastuzumab stored at RT or at 2-8 °C. MicroSPECT/CT demonstrated high uptake in SK-Ov-3 tumours in mice that was not significantly different using trastuzumab stored at RT or at 2-8 °C (33.7 ± 8.8% vs. 22.2 ± 8.1% i.d./g, respectively; P = 0.36). There were no significant differences in normal tissue uptake or in tumour/normal tissue (T/NT) ratios. We conclude that short-term storage of trastuzumab at RT for 12 h did not affect the physicochemical or biological properties of the drug.

Risk of nosocomial transmission of coronavirus disease 2019: an experience in a general ward setting in Hong Kong.

BACKGROUND: Coronavirus disease 2019 (COVID-19) was first reported in Wuhan in December 2019 and has rapidly spread across different cities within and outside China. Hong Kong started to prepare for COVID-19 on 31st December 2019 and infection control measures in public hospitals were tightened to limit nosocomial transmission within healthcare facilities. However, the recommendations on the transmission-based precautions required for COVID-19 in hospital settings vary from droplet and contact precautions, to contact and airborne precautions with placement of patients in airborne infection isolation rooms. AIM: To describe an outbreak investigation of a patient with COVID-19 who was nursed in an open cubicle of a general ward before the diagnosis was made. METHOD: Contacts were identified and risk categorized as 'close' or 'casual' for decisions on quarantine and/or medical surveillance. Respiratory specimens were collected from contacts who developed fever, and/or respiratory symptoms during the surveillance period and were tested for SARS-CoV-2. FINDINGS: A total of 71 staff and 49 patients were identified from contact tracing, seven staff and 10 patients fulfilled the criteria of 'close contact'. At the end of 28-day surveillance, 76 tests were performed on 52 contacts and all were negative, including all patient close contacts and six of the seven staff close contacts. The remaining contacts were asymptomatic throughout the surveillance period. CONCLUSION: Our findings suggest that SARS-CoV-2 is not spread by an airborne route, and nosocomial transmissions can be prevented through vigilant basic infection control measures, including wearing of surgical masks, hand and environmental hygiene.

An emerging role for gasotransmitters in the control of breathing and ionic regulation in fish.

Three gases comprising nitric oxide, carbon monoxide and hydrogen sulphide, collectively are termed gasotransmitters. The gasotransmitters control several physiological functions in fish by acting as intracellular signaling molecules. Hydrogen sulphide, first implicated in vasomotor control in fish, plays a critical role in oxygen chemoreception owing to its production and downstream effects within the oxygen chemosensory cells, the neuroepithelial cells. Indeed, there is emerging evidence that hydrogen sulphide may contribute to oxygen sensing in both fish and mammals by promoting membrane depolarization of the chemosensory cells. Unlike hydrogen sulphide which stimulates breathing in zebrafish, carbon monoxide inhibits ventilation in goldfish and zebrafish whereas nitric oxide stimulates breathing in zebrafish larvae while inhibiting breathing in adults. Gasotransmitters also modulate ionic uptake in zebrafish. Though nothing is known about the role of CO, reduced activities of branchial Na(+)/K(+)-ATPase and H(+)-ATPase activities in the presence of NO donors suggest an inhibitory role of NO in fish osmoregulation. Hydrogen sulphide inhibits Na(+) uptake in zebrafish larvae and contributes to lowering Na(+) uptake capacity in fish acclimated to Na(+)-enriched water whereas it stimulates Ca(2+) uptake in larvae exposed to Ca(2+)-poor water.

Synthesis and characterization of phosphorescent cyclometalated iridium complexes.

The preparation, photophysics, and solid state structures of octahedral organometallic Ir complexes with several different cyclometalated ligands are reported. IrCl3.nH2O cleanly cyclometalates a number of different compounds (i.e., 2-phenylpyridine, 2-(p-tolyl)pyridine, benzoquinoline, 2-phenylbenzothiazole, 2-(1-naphthyl)benzothiazole, and 2-phenylquinoline), forming the corresponding chloride-bridged dimers, CwedgeN2Ir(mu-Cl)2IrCwedgeN2 (CwedgeNis a cyclometalated ligand) in good yield. These chloride-bridged dimers react with acetyl acetone (acacH) and other bidentate, monoanionic ligands such as picolinic acid (picH) and N-methylsalicylimine (salH), to give monomeric CwedgeN2Ir(LX) complexes (LX = acac, pic, sal). The emission spectra of these complexes are largely governed by the nature of the cyclometalating ligand, leading to lambda(max) values from 510 to 606 nm for the complexes reported here. The strong spin-orbit coupling of iridium mixes the formally forbidden 3MLCT and 3pi-pi* transitions with the allowed 1MLCT, leading to a strong phosphorescence with good quantum efficiencies (0.1-0.4) and room temperature lifetimes in the microsecond regime. The emission spectra of the CwedgeN2Ir(LX) complexes are surprisingly similar to the fac-IrCwedgeN3 complex of the same ligand, even though the structures of the two complexes are markedly different. The crystal structures of two of the CwedgeN2Ir(acac) complexes (i.e., CwedgeN = ppy and tpy) have been determined. Both complexes show cis-C,C', trans-N,N' disposition of the two cyclometalated ligands, similar to the structures reported for other complexes with a "CwedgeN2Ir" fragment. NMR data (1H and 13C) support a similar structure for all of the CwedgeN2Ir(LX) complexes. Close intermolecular contacts in both (ppy)2Ir(acac) and (tpy)2Ir(acac) lead to significantly red shifted emission spectra for crystalline samples of the ppy and tpy complexes relative to their solution spectra.

Arabidopsis LEAFY COTYLEDON1 is sufficient to induce embryo development in vegetative cells.

The Arabidopsis LEAFY COTYLEDON1 (LEC1) gene is required for the specification of cotyledon identity and the completion of embryo maturation. We isolated the LEC1 gene and showed that it functions at an early developmental stage to maintain embryonic cell fate. The LEC1 gene encodes a transcription factor homolog, the CCAAT box-binding factor HAP3 subunit. LEC1 RNA accumulates only during seed development in embryo cell types and in endosperm tissue. Ectopic postembryonic expression of the LEC1 gene in vegetative cells induces the expression of embryo-specific genes and initiates formation of embryo-like structures. Our results suggest that LEC1 is an important regulator of embryo development that activates the transcription of genes required for both embryo morphogenesis and cellular differentiation.

Ventricular rupture during coronary angioplasty for acute reinfarction.

Ventricular rupture following acute myocardial infarction usually leads to hemopericardium and death from cardiac tamponade. We describe a patient who had cardiac rupture during direct angioplasty for reinfarction 3 days following an acute anterior myocardial infarction. In this instance, ventricular rupture presented as a severe form of reperfusion injury. The current literature on reperfusion injury and risk factors for cardiac rupture are discussed.

Low-angle X-ray scattering signatures of urinary calculi.

This is the first reported use of low-angle X-ray scattering for the investigation of urinary calculi. Low-angle X-ray scattering (LAXS) measures the diffraction of a broad spectrum of X-rays at a single angle and uses a conventional diagnostic X-ray beam, and could thus be developed for use in vivo. A total of 45 calculi were investigated using this technique. Calcium oxalate stones showed a bimodal signature with peaks of almost even photon energies. Signatures for the other stone types were less well-defined. The results are discussed in more detail below. Our preliminary results show that the technique is capable of distinguishing between calcium oxalate stones and other stone types in vitro. Further work is in progress to correlate the results of this technique with objective parameters of stone hardness.

Contribution of antibody heavy chain CDR1 to digoxin binding analyzed by random mutagenesis of phage-displayed Fab 26-10.

We constructed a bacteriophage-displayed library containing randomized mutations at H chain residues 30-35 of the anti-digoxin antibody 26-10 Fab to investigate sequence constraints necessary for high affinity binding in an antibody of known crystal structure. Phage were selected by panning against digoxin and three C-16-substituted analogues. All antigen-positive mutants selected using other analogues also bound digoxin. Among 73 antigen-positive clones, 26 different nucleotide sequences were found. The majority of Fabs had high affinity for digoxin (Ka 3.4 x 10(9) M-1) despite wide sequence diversity. Two mutants displayed affinities 2- and 4-fold higher than the parental antibody. Analysis of the statistical distribution of sequences showed that highest affinity binding occurred with a restricted set of amino acid substitutions at positions H33-35. All clones save two retained the parental Asn-H35, which contacts hapten and hydrogen bonds to other binding site residues in the parental structure. Positions H30-32 display remarkable diversity, with 10-14 different substitutions for each residue, consistent with high affinity binding. Thus complementarity can be retained and even improved despite diversity in the conformation of the N-terminal portion of the H-CDR1 loop.

Detection of feedback in the central nervous system using system identification techniques.

An analysis method to detect the presence of feedback between biological signals, particularly those associated with the central nervous system, is presented. The technique is based on recent results in the system identification literature involving the concept of a feedback free process. It may be applied to volume conducted signals such as EEG and EMG, as well as to neuronal spike trains through the use of a data transformation procedure. The utility of the technique is then demonstrated in a study of the relationship between Parkinsonian tremor and certain tremor cells found in the thalamus of Parkinsonian patients, using data collected during thalamotomies. The results obtained suggest that feedback mechanisms may be an important factor contributing to Parkinsonian tremor.

Single unit analysis of the human ventral thalamic nuclear group: correlation of thalamic "tremor cells" with the 3-6 Hz component of parkinsonian tremor.

Although cells firing at tremor frequency, called "tremor cells" (Guiot et al., 1962), have often been recorded in the thalamus of parkinsonian patients, the extent of correlation between these spike trains and tremor has rarely been assessed quantitatively. This paper describes spectral cross-correlation functions calculated between the activity of "tremor cells" and electromyogram (EMG) signals recorded from several muscles in the contralateral arm. The power occurring in the spike train at tremor frequency was described in absolute terms by the spike autopower, and in relation to the average for all spectral components by the spike autopower signal-to-noise ratio (spike autopower SNR). The probability of significant cross-correlation between the thalamic spike train and EMG at tremor frequency was assessed by the coherence at tremor frequency. Autopower spectra of the activity of many of these cells exhibited a concentration of power at tremor frequency, indicated by spike autopower SNRs as high as 18. Of the EMG signals studied, signals recorded from finger flexors were most often significantly correlated at tremor frequency. Significant correlation between the thalamic spike train and finger flexor EMG activity was found in 34% of cells analyzed. Tremor frequency coherence was significantly correlated with tremor frequency spike autopower (r = 0.46, p less than 0.0001) and spike autopower SNR (r = 0.533, p less than 0.0001). The proportion of cells with a spike autopower SNR greater than 2 that were significantly correlated with finger flexor EMG activity was greater than that of cells with a spike autopower SNR of less than 2 (p less than 0.001; chi-square). Therefore, cells exhibiting a large amount of power at tremor frequency were those best correlated with EMG activity during tremor. Some of these cells may be involved in the generation of tremor.

Analytic expression for the MTF of an array of circular unaberrated phased apertures.

An exact analytic expression for the MTF of an aberration-free phased array consisting of identical round subtelescopes is derived. This formula is employed to study several cases of phased array configurations, to gain insights on MTF trends for various subtelescope number and location. Perspective plots of the MTF patterns and their cross section across orthogonal axes are generated and presented.

Selection of the optimal lesion site for the relief of parkinsonian tremor on the basis of spectral analysis of neuronal firing patterns.

Techniques for quantitatively describing the firing properties of neurons have been used to identify thalamic cells with a firing pattern which is correlated with EMG activity during tremor. By locating these cells relative to the anterior border of the somatosensory nucleus and the anterior commissure-posterior commissure line, it may be possible to select the optimal lesion site for the relief of parkinsonian tremor on a rational rather than an empirical basis.

The role of feedback in the tremor frequency activity of tremor cells in the ventral nuclear group of human thalamus.

Close loop system identification techniques have been used to identify the presence of feedback in the firing pattern of thalamic tremor cells recorded in parkinsonian tremor patients.

Cross-correlation analysis of thalamic neurons and EMG activity in parkinsonian tremor.

Bursting activity in cells cross-correlated with electromyographic (EMG) activity during parkinsonian tremor. Statistically significant evidence of cross-correlation was found for 49% of cells located at the lesion target for relief of tremor. Statistically significant correlation was found for 90% of cells having tremor frequency power greater than twice 'average power' at nontremor frequencies. This population of cells may be involved in the generation of parkinsonian tremor.

Vinblastine, intermittent bleomycin, and single-dose cis-dichlorodiammineplatinum(II) in the management of stge III testicular cancer.

A program for treating advanced testicular cancer with vinblastine, bleomycin, and a single dose of cis-dichlorodiammineplatinum(II) was used in an attempt to reduce the toxicity of a 5-day regimen while maintaining a high response rate. In ten previously untreated and six previously treated patients, the complete remission rate was 25%. Toxic reactions were frequent, and there was one drug-related death. This single-dose cis-dichlorodiammineplatinum(II) program is ineffective in the treatment of testicular cancer. Other means for reducing toxicity will have to be considered.