Acid-induced transformations of myoglobin. Characterization of a new equilibrium heme-pocket intermediate

The pH dependence of the absorption and resonance Raman (RR) spectra of the deoxy and met forms of myoglobin (Mb) has been examined in detail. The spectral data were acquired at a number of different pHs (12) in the 2.6-7.6 range. RR spectra were obtained for both the low- and high-frequency regions by using a variety of excitation wavelengths ranging from the UV to the green. The data obtained for deoxyMb indicate that a spectroscopically distinct intermediate (I') exists at equilibrium in the pH 3.5-4.5 range. The I'-form of metMb could not be identified. The Soret absorption maximum of the I'-form of deoxyMb is at approximately 426 nm compared with the value of 435 observed for the native (N) form and 383 nm observed for the so-called unfolded (U') form which occurs in the pH 2.6-3.5 range. The absorption and vibrational spectra of the I'-form of deoxyMb observed at equilibrium are very similar to those of the intermediate that appears within a few milliseconds in pH-jump experiments. The RR data indicate that the structure of the heme group in the I'-form is distinctly different from that of either N- or U'-forms. The iron-histidine bond, characteristic of the N-form, is ruptured in both the I'- and U'-forms as is evidenced by the absence of the RR band due to the stretching vibration of this unit. In the I'-form, the histidine ligand is replaced by a relatively strongly bound, exchangeable water molecule. This ligand is absent in the U'-form. The aquo ligand of the five-coordinate heme in the I'-form is identified by a RR band at 411 cm-1 which undergoes a 15-17 cm-1 downshift in deuteriated buffer solutions. In contrast, none of the RR bands of the N- and U'-forms exhibit any significant isotope sensitivity. The properties of the I'-form and the conditions under which it is generated strongly suggest that this form corresponds to the molten globule intermediate of apoMb.

Elective cerclage vs. ultrasound-indicated cerclage in high-risk pregnancies

OBJECTIVE

To compare pregnancy outcome after elective vs. ultrasound-indicated cervical cerclage in women at high risk of spontaneous mid-trimester loss or early preterm birth.

METHODS

This was a retrospective study comparing two management strategies in women with singleton pregnancies who had at least one previous spontaneous delivery at 16-33 weeks of gestation. One group was managed by the placement of an elective cerclage at 12-16 weeks and the other group had transvaginal ultrasound examinations of the cervix at 12-15+6, 16-19+6, and 20-23+6 weeks and cervical cerclage was carried out if the cervical length was 25 mm or less.

RESULTS

A total of 90 patients were examined, including 47 that were managed expectantly and 43 treated by elective cerclage. In the expectantly managed group, 59.6% (28/47) required a cervical cerclage. We excluded from further analysis three patients who were lost to follow-up and three because of fetal death or iatrogenic preterm delivery. Miscarriage or spontaneous delivery before 34 weeks' gestation occurred in 14.6% (6/41) of the elective cerclage group, compared with 20.9% (9/43) in the expectantly managed group (chi2 = 0.219, P = 0.640).

CONCLUSION

In women at increased risk of spontaneous mid-trimester or early preterm delivery, a policy of sonographic surveillance followed by cervical cerclage in those with a short cervix reduces the need for surgical intervention without significantly increasing adverse pregnancy outcome.

Qy-excitation resonance Raman scattering from the special pair in Rhodobacter sphaeroides reaction centers. Implications for primary charge separation

Qy-excitation resonance Raman (RR) spectra are reported for reaction centers (RCs) from Rhodobacter sphaeroides 2.4.1. The RR spectra were acquired for both chemically reduced and oxidized RCs at 25 and 201 K by using a variety of excitation wavelengths in the range 800-920 nm. This range spans the Qy absorption bands of the special pair (P) and the accessory bacteriochlorophylls (BChls). The RR studies indicate that both P and the accessory BChls exhibit rich RR spectra in the 30-1800-cm-1 region. For both types of pigments, at least 20 bands are observed in the 30-750-cm-1 range. Although the frequencies of the modes of P and the accessory BChls are different, it is possible to make one-to-one correlations of the bands observed for the two types of pigments. This result suggests that the vibronically active low-frequency modes of P are derived from monomer-like vibrations (although they may be coupled monomer-like modes) rather than being vibrations resulting from the additional degrees of freedom present in the dimer. A plausible set of vibrational assignments for the low-frequency modes of both P and the accessory BChls is proposed on the basis of a semiempirical normal coordinate calculation. Comparison of the RR intensities of the low-frequency modes of P with those of the analogous modes of the accessory BChls indicates that the intensities of the modes of the former pigments are considerably larger than those of the latter. Collectively, the spectral data indicate that a large number of low-frequency modes of P are strongly coupled to the Qy electronic transition.(ABSTRACT TRUNCATED AT 250 WORDS)

Resonance Raman characterization of H(M200)L mutant reaction centers from Rhodobacter capsulatus. Effects of heterodimer formation on the structural and electronic properties of the cofactors

Resonance Raman (RR) spectra are reported for photosynthetic reactions centers (RCs) from the H(M200)L mutant of Rhodobacter capsulatus. In this mutant, the histidine residue which ligates the M-side bacteriochlorophyll (BCh) of the special pair primary donor (P) of wild-type RCs is replaced by a noncoordinating leucine. This results in the formation of a heterodimer primary donor (D) in which a bacteriopheophytin (BPh) replaces the M-side BCh. The RR data for the H(M200)L mutant were acquired at a large number of excitation wavelengths which span the B, Qx, and Qy absorption bands of the various bacteriochlorin cofactors in the RC. For comparison, spectra were also acquired for wild-type RCs at the same excitation wavelengths. The RR data obtained for the mutant indicate that heterodimer formation induces a variety of changes in the structural and electronic properties of the cofactors in the RC. These perturbations extend beyond the primary donor and include one of the two accessory BChs. Collectively, the RR studies indicate the following: (1) The structure of the single BCh cofactor in D [DL(BCh)] is different from that of either of the two BChs in P. However, DL(BCh) is more similar to PL than to PM. The PM cofactor is conformationally more distorted than either PL or DL(BCh). (2) The structure of the BPh cofactor in D [DM(BPh)] is similar to that of the other two BPhs in the RC. However, the frequency of the C9-keto carbonyl mode of DM(BPh) is anomalously low (1678 cm-1), as is also the case for PM. The vibrational characteristics of the C9-keto carbonyl vibrations of DM(BPh)/PM versus DL(BCh)/PL are consistent the notion that dielectric effects govern the frequency of the mode and that the effective dielectric constant is different on the L- versus M-sides of the primary donor. (3) Heterodimer formation perturbs the structural and electronic properties of one of the two accessory BChs (most likely BChL) in the RC. These perturbations are manifested as upshifts in the ring skeletal-mode frequencies and a blue-shift in the Qx absorption band (from 600 to 580 nm). The fact that heterodimer formation perturbs one of the accessory BChs suggests that global structural rearrangements occur in the protein matrix when the ligand to a cofactor in the primary donor is removed. (4) For both the H(M200)L mutant and wild-type RCs, oxidation of the primary donor significantly affects the RR cross section of the carotenoid.(ABSTRACT TRUNCATED AT 400 WORDS)

Resonance Raman spectroscopy of horseradish peroxidase derivatives and intermediates with excitation in the near ultraviolet

Resonance Raman enhancement of derivatives and intermediates of horseradish peroxidase in the near ultraviolet (N-band excitation) results in intensity and enhancement patterns that are different from those normally observed within the porphyrin Soret (B-band) and alpha-beta (Q-band) absorptions. In particular it allows the resolution of resonance Raman spectra of horseradish peroxidase compound I. The bands above 1300 cm-1 can be assigned to porphyrin vibrational modes that are characteristically shifted in frequency due to removal of an electron from the porphyrin ring. The resonance Raman frequency shifts follow normal mode compositions. Relative to resonance Raman spectra of compound II, the v4 frequency (primarily Ca-N) exhibits a 20 cm-1 downshift. The v2, v11, and v37 vibrational frequencies whose mode compositions are primarily porphyrin Cb-Cb, exhibit 10-20 cm-1 upshifts. The v3, v10, and v28 frequencies, whose mode compositions are primarily Ca-Cm, exhibit downshifts. The downshifts for v3 and v10 are small, 3-5 cm-1; however, the downshift for v28 is 14 cm-1. These frequency shifts are consistent with those of previously published resonance Raman studies of model compounds. In contrast to reports from other laboratories, the data presented here for horseradish peroxidase compound I can be attributed unambiguously to resonance Raman scattering from a porphyrin pi-cation radical.

746 Single-Centre Experience with Three Metallic Ureteric Stents (Allium URS, Memokath-051 and Resonance) for Chronic Ureteric Obstruction

Aim

To evaluate efficacy of Allium URS, Memokath 051 and Resonance metallic ureteric stents as an alternative to polymer stents/nephrostomy in managing chronic ureteric obstruction (CUO).

Method

Retrospective analysis of consecutive patients with CUO managed with Allium URS, Memokath-051 or Resonance (September 2015/July 2020). Baseline patient variables (age, gender, underlying aetiology, ASA) and stricture characteristics (length, level, continuity) were recorded. Intra- and post-operative clinical and radiological follow-up assessments at 6 weeks, 3 months and then every 6 months, as well as any emergency attendances, were reviewed for placement success, stent complications, serum creatinine, and mortality. Outcomes included placement success rate, functional stent survival, and mean renal function.

Results

Overall, 129 stent insertion episodes (SIEs) (Allium URS: 23, Memokath 051: 48, Resonance: 58) occurred in 76 patients (Allium URS: 16; Memokath-051: 31; Resonance: 29). Placement success was high (Allium URS: 95.7%; Memokath-051 and Resonance: both 100%). Median functional stent survival was 11.4 months for Allium URS, 5.5 months for Memokath-051 and 11.7 months for Resonance. 47.8% of Allium URS SIEs (11/23), 64.6% of Memokath-051 SIEs (31/48) and 19% of Resonance SIEs (11/58) experienced complication (most frequently obstruction followed by migration and infection). There were no complications for Resonance SIEs for benign indication. In the first year following SIE, serum creatinine ranged from +21.3% to + 46.7% for Allium URS, -7.8% to + 8.9% for Memokath-051, and -9.4% to + 27.3% for Resonance.

Conclusions

Allium URS, Memokath 051 and Resonance metallic ureteric stents are all viable management options of CUO. Resonance was particularly efficacious for patients with benign aetiology.

Suicidal ideation and biogenic amines in depression

This report is based on the study of 40 depressives in an attempt to explore the possible association between the suicidal ideas and the biogenic amines. The severity of suicidal ideas was measured on Hamilton Depressive Rating Scale and their amine metabolites were measured (MHFG, HVA and 5 HIAA) in urine and C.S.F. It was observed that the level of 5 HIAA, and Serotonin (5 HT) was more related to suicidal ideas and was inversely related. The probable associations between these are discussed.

Urban mental health services in India : how complete or incomplete?

The information about Urban Mental Health Services has been nearly nonexistent in India, although the developed countries have been focusing on programmes for "Healthy Cities". The initiative taken as part of the WHO-ICMR Pilot Project on Urban Mental Health Services, with a public health perspective is being shared. The objectives of the Health Services Research (HSR) Arm of the project were to study the distribution and the availability of tertiary Mental Health Services, availability of human resources, average service load, mental health service gap, and perceptions of the users and the service providers, regarding the barriers in accessibility of mental health services, unmet service needs and strategies for improvement.The Research Methods involved Mapping Exercises with estimation of Service Loads and Qualitative Research Methods (QRM) like In-Depth Interviews (IDIs), Key Informant Interviews (KIIs), Free Listing and Focused Group Discussions (FGDs). The results indicate uneven availability of mental health services, human resource deficit specially for non-medical mental health professionals and mental health service gap (82% to96%). The average service load in the specialist mental health services is largely carried by the Govt. sector (half to two thirds), followed by the private sector (one third to half), with only a small portion by the NGO sector. The average mental health service load in the primary care general health services is largely carried by the private sector, with significant contribution from the non-formal service providers. The barriers to access, unmet needs and possible strategies as perceived by the community, users and service providers have been identified. The findings are discussed in the context of the mental health programmes and the public policy issues. The implications of the conclusions which suggest that Urban Mental Health Services are far from complete are highlighted.

Resonance Raman spectroscopy of the catalytic intermediates and derivatives of chloroperoxidase from Caldariomyces fumago

Near-ultraviolet resonance Raman spectra of chloroperoxidase derivatives and high valent intermediates show frequencies that can be systematically assigned. In accord with previous observations of low v4 frequencies for the ferric enzyme, and quite low v4 frequencies for the ferrous enzyme, low v4 frequencies are observed for ferryl compound II and several ferric derivatives. Resonance Raman spectra of chloroperoxidase compound I feature upshifted v2, v11, and v37 frequencies and other characteristics that argue for a 2A1u in preference to a 2A2u ground state for the porphyrin phi-cation radical. A moderately intense anomalously polarized band is observed at a frequency typical for octaethylporphyrin phi-cation radicals, which have been previously assigned as the 2A1u radical type. Similar resonance Raman spectral attributes are observed for horseradish peroxidase compound I, supporting a 2A1u symmetry state assignment for this species also. A 2A1u symmetry state assignment for chloroperoxidase and horseradish peroxidase compounds I is consistent with the beta-pyrrole substituent pattern of the protoporphyrin hemes found in these enzymes.