trans−cis Photoisomerization of a Photoactive Yellow Protein Model Chromophore in Crystalline Phase

We have studied the photoinduced trans/cis isomerization of the protonated form of p-hydroxycinnamic thiophenyl ester, a model chromophore of the photoactive yellow protein (PYP), in crystalline phase, by both fluorescence and infrared spectroscopies. The conversion from trans to cis configuration is revealed by a shift of the fluorescence peak and by inspection of the infrared maker bands. The crystal packing apparently stabilizes the cis photoproduct, suggesting different environmental effects from the solvent molecules for this model chromophore in liquid solutions or from the amino acid residues for the PYP chromophore.

Structural evolution of the chromophore in the primary stages of trans/cis isomerization in photoactive yellow protein

We have studied the structural changes induced by optical excitation of the chromophore in wild-type photoactive yellow protein (PYP) in liquid solution with a combined approach of polarization-sensitive ultrafast infrared spectroscopy and density functional theory calculations. We identify the nuC8-C9 marker modes for solution phase PYP in the P and I0 states, from which we derive that the first intermediate state I0 that appears with a 3 ps time constant can be characterized to have a cis geometry. This is the first unequivocal demonstration that the formation of I0 correlates with the conversion from the trans to the cis state. For the P and I0 states we compare the experimentally measured vibrational band patterns and anisotropies with calculations and find that for both trans and cis configurations the planarity of the chromophore has a strong influence. The C7=C8-(C9=O)-S moiety of the chromophore in the dark P state has a trans geometry with the C=O group slightly tilted out-of-plane, in accordance with the earlier reported structure obtained in an X-ray diffraction study of PYP crystals. In the case of I0, experiment and theory are only in agreement when the C7=C8-(C9=O)-S moiety has a planar configuration. We find that the carboxylic side group of Glu46 that is hydrogen-bonded to the chromophore phenolate oxygen does not alter its orientation on going from the electronic ground P state, via the electronic excited P state to the intermediate I0 state, providing conclusive experimental evidence that the primary stages of PYP photoisomerization involve flipping of the enone thioester linkage without significant relocation of the phenolate moiety.

Continuing communicable disease burden in Eritrea

BACKGROUND AND METHODS

A retrospective study of the national health profile of Eritreans, focusing on acute respiratory tract infection (ARTI), tuberculosis (TB), diarrhoea, sexually transmitted diseases (STDs) and HIV/AIDS, was done on data from 1998 to 2003 through a health information management system. Records were included for patients of all ages receiving outpatient and inpatient hospital services during the study period. All incidence rates were given as cases per 100,000 population.

RESULTS

The incidence of ARTI increased from 6,500 cases per annum in 1998 to 8 500 in 2003, representing a 30% increase. Diarrhoea rates remained unchanged, averaging 3,000 cases. For both ARTI and diarrhoea, rates were at least 3 times higher in children under 5 years of age than in those over 5 years of age. The incidences of TB and STDs decreased from 370 and 220 in 1998 to 170 and 80 in 2003, respectively. HIV/AIDS incidence increased from 40 in 1998 to 65 in 2003, reflecting a 60% increase. The case fatality rates (CFRs) for HIV/AIDS and TB were 12% and 2% in 1998, increasing to 14% and 3%, respectively, in 2001. The CFR for ARTI and diarrhea remained low at 0.3%. CFRs were higher in children under 5 years than in those over 5 years for all the diseases but rates declined consistently, probably reflecting the positive impact of the introduction of the integrated management of childhood illness (IMCI). Although the incidence rate of HIV/AIDS was relatively low compared with rates for TB, ARTI and diarrhoea, the HIV/AIDS CFR was relatively high, posing a threat to the gains made in control of infectious diseases. The disease burden from TB and STDs declined over the 6-year study period, while that from ARTI and HIV/AIDS increased. Consequently the overall disease burden from communicable diseases remained unchanged over the study period.

The prevalence of hypertension and its relationship with obesity: results from a national blood pressure survey in Eritrea

The prevalence of cardiovascular diseases has been shown to be on the increase in Africa based on hospital-based information and limited national surveys. A recent report on analysis of data from Health Information Management Systems (HIMS) highlighted an increasing burden of noncommunicable diseases (NCDs) in Eritrea, with the incidence of hypertension doubling in a space of 6 years. HMIS data are only a proxy of national prevalence rates, necessitating the conduct of national surveys. The WHO STEPwise approach to surveillance of NCDs was used for the national NCD risk factor survey in 2004. This report focuses on blood pressure (BP) and obesity (body mass index (BMI) > 30 kg/m2) as NCD risk factors in Eritrea. A total of 2352 people in age groups 15 to 64 years participated in the survey. The prevalence of hypertension defined as BP > 140/90 mmHg was 15.9% in the general population, with 16.4% in urban and 14.5% in rural areas, 17% of whom were males while 15% were females. BMI was positively associated with systolic (SBP), diastolic and mean arterial pressure. Although the prevalence of obesity (3.3%) was higher in females, the effect of BMI on BP was higher in males than in females (regression coefficient 0.64 and 0.38, respectively, P < or = 0.05), especially in those >45 years. BMI did not have a significant effect on BP in lean people (BMI < 19) and in those with high BMI, but was positively correlated to SBP in those with normal BMI (P < or = 0.02). BMI and age appear to play a synergistic role in creating a strong association with BP.

Excited-State Structure Determination of the Green Fluorescent Protein Chromophore

Ultrafast polarization-sensitive infrared (IR) spectroscopy of the C=O stretching mode of the chromophore of the green fluorescent protein reveals a near complete twisting around the ethylenic bridge between the phenolate and imidazolidinone groups upon electronic excitation, hinting at a decisive role of this motion in the efficient internal conversion process.

Recurrent cholera epidemics in Kano--northern Nigeria

OBJECTIVES

The study examined the factors associated with recurrent cholera epidemics in Kano State of Northern Nigeria, the management of the epidemics and health outcomes.

METHODS

Using epidemiological data from the Public Health Department of the Kano State Ministry of Health, the study examined the frequency and geographical distribution of the epidemics for the period 1995 to 2001; procedures for detection; control measures as well as results of biological and bacteriological testing of water from different sources. Mapping and testing for significance of faecal contamination of water sources were done.

RESULTS

The number of cholera cases in the city was 2 630; 847 and 2 347 in 1995/6, 1997 and 1999 respectively. The State Epidemiological Unit which is responsible for surveillance detected epidemics using set thresholds and activated multi-sectoral emergency responses. Control measures encompassed accurate diagnosis at the reference laboratory, Kaduna; registration of cases; case management and public health measures targeting personal hygiene and water treatment. The cholera epidemics attracted worldwide attention with emergency responses from many agencies including WHO, UNICEF and Medicens Sand Frontiers (MSF). Case fatality rates decreased from 15% in 1995/6 to 5% in 1997 and 2% in 1999. The organism responsible for all the outbreaks was Vibrio cholerae, el-tor of inaba serotype. Water contamination of all sources was the principal cause of the epidemics. There were statistically significant differences in levels of faecal contamination of water sources, wells being most affected, followed by piped water, chi2 = 11.556, (p < 0.02). Bore holes were relatively safer sources of water. Point source epidemics always started from Kano City before fanning out to the rest of the State.

CONCLUSION

Multi-sectoral Epidemic Preparedness and Response (EPR) approaches have contributed to the reduction in case fatality rates over the years and should be sustained. However, in order to prevent future cholera epidemics, there is need to introduce intervention measures that address the root problems of poor sanitation and unsafe water supplies.

Magneto−Structural Correlations: Synthesis of a Family of End-On Azido-Bridged Manganese(II) Dinuclear Compounds with S = 5 Spin Ground State

The preparation of a series of multidentate pyridyl-imine ligands, L1-L3, and their reactivity with the Mn(II)/N3- system is described (L1 = [N,N-bis(pyridine-2-yl)benzylidene]ethane-1,2-diamine; L2 = [N,N-bis(pyridine-2-yl)benzylidene]propane-1,3-diamine, and L3 = [N,N-bis(pyridine-2-yl)benzylidene]butane-1,4-diamine). Complexes comprising dinuclear end-on bis(mu-azido)-bridged manganese(II) units of formulas [Mn2(L1)2(N3)4][Mn2(L1)2(N3)2(CH3OH)2](ClO4)2 (two cocrystallized dinuclear units, 1.2), [Mn2(L2)2(N3)2](ClO4)2 (3), and [Mn2(L3)2(N3)2](ClO4)2 (4) have been synthesized. The crystal structures of complexes 1-4 as well as their magnetic properties are presented. Each manganese atom of cocrystallized complexes in compound 1.2 is heptacoordinated, displaying Mn-N-Mn angles, theta, of 102.53(12) and 101.70(12) degrees and Mn...Mn distances of 3.5091(7) and 3.4680(7) A. On the other hand, each manganese center in compounds 3 and 4 is located within an octahedral coordination environment, the complexes displaying theta angles of 104.29(11) and 103.60(18) degrees , respectively, and Mn...Mn vectors of 3.5371(7) and 3.5338(10) A, respectively. Magnetic susceptibility studies revealed the presence of intramolecular ferromagnetic superexchange, yielding an S = 5 spin ground state in all complexes. Fitting of the experimental data led to coupling constants, intermolecular exchange values, and g factors (in the J/zJ'/g format) of 0.77 cm(-1)/0.01 cm(-1)/2.20 (1.2), 2.04 cm(-1)/0.01 cm(-1)/1.99 (3), and 1.75 cm(-1)/-0.05 cm(-1)/2.04 (4), respectively (using H = -2JS1S2 as the convention for the Heisenberg spin-Hamiltonian). These results are consistent with predictions from recent DFT calculations performed on end-on bis(mu-N3-)-bridged Mn(II) dinuclear complexes. A plot of experimental J vs theta, including data from the only preexisting compound of this kind, reveals a linear relationship, which could be the first evidence of a possible magneto-structural correlation between these two parameters.

Crystal structure, spectroscopic studies, and nonlinear optical (NLO) properties of Schiff base metal complexes containing an N, S donor ligand

A new ligand, 4-dipropylaminobenzaldehyde thiosemicarbazone (abbreviated as HL), and its complexes ML2 (M = Ni, Pd, and Cu) have been synthesized and fully characterized by elemental analyses, EI-MS, IR and UV–vis spectroscopy, and photoluminescence measurements. All of the compounds exhibit a blue–green color with dual fluorescence in DMF solution. The quantum yield ratio (Φ′(CT)/Φ(LE)) decreases in the order NiL2 > HL > PdL2 > CuL2. The ligand HL crystallizes in the monoclinic system, space group P21/n, with a = 15.1680, b = 8.5573, and c = 25.3920 Å, β = 100.3457°, and V = 3242.2 Å3. The nickel complex (NiL2) crystallizes in the triclinic system, space group Pī, with a = 8.3093, b = 9.7540, and c = 10.2802 Å, α = 101.383°, β = 107.693°, γ = 96.703°, and V = 764.12 Å3. In these complexes, HL has lost a proton from its tautometric thiol form and acts as a single negatively charged bidentate ligand coordinating to the nickel ion via the mercapto sulfur and β-nitrogen atoms. The geometry around Ni(II) is almost square-planar with two equivalent Ni—N and two equivalent Ni—S bonds. The monomeric structure of HL or NiL2 is extended into an infinite two-dimensional network via hydrogen bonds. The two-photon absorption of HL and ML2 solutions (in DMF) was measured at 532 nm by the open-aperture Z-scan technique. Key words: crystal structure, metal complex, dual fluorescence, NLO.

Orbital embryonal rhabdomyosarcoma in Karachi (1998-2002)

OBJECTIVE

To study the epidemiology of ocular Rhabdomyosarcoma (ORMS) in Karachi.

METHODS

Incident ORMS cases resident of Karachi, registered at Karachi Cancer Registry (KCR) during 1st January 1998 to 31st December 2002 were included in the study. The data were classified using ICD-O2; computerized with Canreg-3, and analyzed using SPSS 10.0.

RESULTS

Ten cases of ORMS were reported to KCR during 1998-2002. RMS originated in the orbit in eight cases, conjunctiva in one and eyelid in one. Nine cases presented with proptosis, associated with conjunctivitis in four cases. One case presented with eyelid swelling. The crude annual incidence rate was 0.13/100,000, the age standardized rate was 0.3/100,000. The mean age of childhood cases was 10.4 years (95% CI 4.0; 16.7); and adult cases was 24.8 years (95% CI 12.8; 36.7). At presentation, eight patients were older than 10 years and three were older than 20 years. Five cases were categorized as childhood malignancies. Tumors were a TNM stage III disease at presentation in eight cases; survival at the end of one year was 70%, and at the end of two years 20%. There were no survivors at the end of three years.

CONCLUSION

ORMS in Karachi is a disease with a dismal survival. It may reflect a late presentation, or shorter adult ORMS survival or a manifestation of a different genetic pattern, associated with rapid evolution and poor prognosis. Health education for the population, especially parents and health providers is essential for early ORMS diagnosis. Pediatricians, ophthalmologists and health professionals, can play a vital role. Healthcare planning should focus on capacity building for ophthalmologic screening. Cytogenetic studies are advised to determine the genetic pattern.

Cancer esophagus Karachi 1995-2002: epidemiology, risk factors and trends

OBJECTIVE

To study the trends of cancer esophagus in Karachi South during 1995-2002 and identify risk factors.

METHODS

Incident esophageal cancer cases recorded at the Karachi Cancer Registry for Karachi South, during 1st January 1995 to 31st December 2003 were reviewed. For maximum completion of data, incident cases registered from 1st January 1995 to 31st December 2002 were included for final analyses.

RESULTS

The Age Standardized Incidence Rates (ASIRs) of cancer esophagus in Karachi South for males were 6.5/100,000 (1995-1997) and 6.4/100,000 (1998-2002). In females the observed rates were 7.0/100,000 (1995-1997) and 8.6/100,000 (1998-2002).

CONCLUSION

In the moderately high incidence, cancer esophagus zone of Karachi, the ASIRs in males remained stable during the last decade, but in females, an upward trend was observed suggesting a progressively higher exposure to risk factors in the latter. The potential risk factors in Karachi are use of all forms of tobacco, areca nut, infrequent consumption of raw fruits and vegetables and diet deficiencies. There is a necessity to actively control the proven risk factors and address the existence of other risk factors. The primary recommended strategy for the control of cancer esophagus would therefore be legislation against tobacco and areca nut in Pakistan and public health education. The risk factors of cancer esophagus identified in this article need to be further confirmed.

Redetermination of hydronium perchlorate at 193 and 293 K

A sample of hydronium perchlorate, H(3)O(+) x ClO(4)(-), crystallized from ethanol at ambient temperature, was found to be orthorhombic (space group Pnma) at both 193 and 293 K, with no phase transition observed in this temperature range. This contrasts with the earlier observation [Nordman (1962). Acta Cryst. 15, 18-23] of a monoclinic phase (space group P2(1)/n) at 193 K for crystals grown at that temperature from perchloric acid. The hydronium and perchlorate ions lie across a mirror plane but it is not possible to define at either temperature a simple description of the H-atom positions due to the three-dimensional tumbling of the hydronium cation.

New Modes of Coordination for the β-Disulfoxide Ligand. The Crystal and Molecular Structure of [{UO2(DBM)2}2PhSOCH2SOPh]

The X-ray structure of the compound [{UO2(DBM)2}2C6H5SOCH2SOC6H5] confirms the bridging bidentate mode of coordination for the β-disulfoxide ligand C6H5SOCH2SOC6H5.

Crystal structure of 4-di(2-pyridinoamino)methylbenzaldehyde, C18H16N4O

C18H16N4O, monoclinic, P121/c1 (No. 14), a = 10.7420(6) Å, b = 12.7228(7)Å, c = 11.8769(7)Å, β = 105.495(1)°, V = 1564.2Å3, Z = 4, Rgt(F) = 0.045, wRref(F2) = 0.125, T = 298 K.