Muhammad Saif Ullah Khan

Status of heavy metal residues in fish species of Pakistan.

In this review, we evaluate and summarize the available data that addresses the levels of HM that exist in aquatic species, mainly fish, of Pakistan. Data on this topic were collected from the literature of the last two decades (1990-2012). Results revealed that the highest number (>50%) of studies addressing HM-contaminated fish have occurred in the Punjab province, followed by the Sindh and Khyber Pakhtunkhwa provinces. Our review disclosed that the HM concentrations in Pakistani fish species varied considerably with location. Generally, the level of HM residues detected in fish species had the following descending order: Fe>Zn>Pb>Cd>Hg>Ni>Cu>Ag>Cr>Mn>As. Fish samples collected from the Kabul River near the Nowshera district, Stretch of Ravi River, Indus River near Mainwali district, and Arabian Sea at Karachi revealed extremely high HM concentrations (range: 0.34-8,381.30 jlg/g), compared to other fresh water bodies, such as the Llyold Barrage, Guddu Barrage, Jinnah Barrage, and Chashma Barrage (0.01-2.13 jlg/g). As a reference point, we also reviewed selected data on HM fish residues that exist in countries that neighbor Pakistan. With the exception of fish collected in India, the majority of fish analyzed for HM residues in neighboring countries displayed lower residues than did fish from Pakistan. We concluded from reviewing the available published data that the most probable sources for the HM contaminants found in Pakistani water and fish were release of domestic sewage, agricultural runoff, and industrial effluents. We strongly recommend that action be taken to better control the discharges of unregulated waste that enters the Pakistani aquatic environment, with the intent to mitigate any continuing future damage to the aquatic ecosystem. We also recommend intensifying research programs that address the toxicity of HM to the aquatic environment, so that a better understanding of metal effects on fish can be achieved that will lead to a sustainable ecological harmony in Pakistan.

A New Ferrocene‐Containing Polyamide Prepared from an Improved Synthesis of 1,1′‐Ferrocene Dicarbonyl Chloride and Ferrocene‐Based Diamine

Abstract 1,1′‐Ferrocene dicarbonyl chloride was prepared by an improved and efficient conversion method from 1,1′‐ferrocene dicarboxylic acid and reacted by esterification with p‐nitrophenol, followed by reduction, to form a ferrocene‐based diamine, 1,1′‐ferrocene bis (p‐amino phenylate). The diamine was characterized by elemental analysis, 1H NMR, and Fourier transform infrared (FTIR) spectroscopy and subsequently condensed with 1,1′‐ferrocene dicarbonyl chloride to form a novel main chain ferrocene‐containing polyamide, poly{imino ferrocene bis (p‐amino phenylate) ferrocenyl}. Its polymeric nature was confirmed by its physical properties, elemental analysis, FTIR spectroscopy, differential scanning calorimetry, and thermogravimetric studies.

Single vs dual (en bloc) kidney transplants from donors ≤ 5 years of age: A single center experience

AIM To compare outcomes between single and dual en bloc (EB) kidney transplants (KT) from small pediatric donors. METHODS Monocentric nonprospective review of KTs from pediatric donors ≤ 5 years of age. Dual EB KT was defined as keeping both donor kidneys attached to the inferior vena cava and aorta, which were then used as venous and arterial conduits for the subsequent transplant into a single recipient. Donor age was less useful than either donor weight or kidney size in decision-making for kidney utilization as kidneys from donors < 8 kg or kidneys < 6 cm in length were not transplanted. Post-transplant management strategies were standardized in all patients. RESULTS From 2002-2015, 59 KTs were performed including 34 dual EB and 25 single KTs. Mean age of donors (17 mo vs 38 mo, P < 0.001), mean weight (11.0 kg vs 17.4 kg, P = 0.046) and male donors (50% vs 84%, P = 0.01) were lower in the dual EB compared to the single KT group, respectively. Mean cold ischemia time (21 h), kidney donor profile index (KDPI; 73% vs 62%) and levels of serum creatinine (SCr, 0.37 mg/dL vs 0.49 mg/dL, all P = NS) were comparable in the dual EB and single KT groups, respectively. Actuarial graft and patient survival rates at 5-years follow-up were comparable. There was one case of thrombosis resulting in graft loss in each group. Delayed graft function incidence (12% dual EB vs 20% single KT, P = NS) was slightly lower in dual EB KT recipients. Initial duration of hospital stay (mean 5.4 d vs 5.6 d) and the one-year incidences of acute rejection (6% vs 16%), operative complications (3% vs 4%), and major infection were comparable in the dual EB and single KT groups, respectively (all P = NS). Mean 12 mo SCr and abbreviated MDRD levels were 1.17 mg/dL vs 1.35 mg/dL and 72.5 mL/min per 1.73 m(2) vs 60.5 mL/min per 1.73 m(2) (both P = NS) in the dual EB and single KT groups, respectively. CONCLUSION By transplanting kidneys from young pediatric donors into adult recipients, one can effectively expand the limited donor pool and achieve excellent medium-term outcomes.

Solid-state 13C, 15N and 29Si NMR characterization of block copolymers with CO2 capture properties

Natural abundance solid‐state multinuclear (13C, 15N and 29Si) cross‐polarization magic‐angle‐spinning NMR was used to study structures of three block copolymers based on polyamide and dimethylsiloxane and two polyamides, one of which including ferrocene in its structure. Assignment of most of the resonance lines in 13C, 15N and 29Si cross‐polarization magic‐angle‐spinning NMR spectra were suggested. A comparative analysis of 13C isotropic chemical shifts of polyamides with and without ferrocene has revealed a systematic shift towards higher δ ‐values (de‐shielding) explained as the incorporation of paramagnetic ferrocene into the polyamide backbone. In addition, the 13C NMR resonance lines for ferrocene‐based polyamide were significantly broadened, because of paramagnetic effects from ferrocene incorporated in the structure of this polyamide polymer. Single resonance lines with chemical shifts ranging from 88.1 to 91.5 ppm were observed for 15N sites in all of studied polyamide samples. 29Si chemical shifts were found to be around −22.4 ppm in polydimethylsiloxane samples that falls in the range of chemical shifts for alkylsiloxane compounds. The CO2 capture performance of polyamide‐dimethylsiloxane‐based block copolymers was measured as a function of temperature and pressure. The data revealed that these polymeric materials have potential to uptake CO2 (up to 9.6 cm3 g−1) at ambient pressures and in the temperature interval 30–40 °C. Copyright

Deceased Donor Kidney Transplantation in Patients Aged 70 and Older: Is 70 the New 50?

Background: Deceased donor (DD) kidney transplantation (KT) outcomes in patients who are aged 70 years and older are understudied. Methods: We retrospectively reviewed our single center DD KT outcomes in patients aged 70 years and older. All patients received antibody induction with tacrolimus, half-dose mycophenolate, ± steroids. Results: Over 10.75 years, we performed 114 KTs in 112 patients aged 70 and older (mean 73.8, range 70-84 years) including 42 patients who were aged 75 and older. The study group included 60 males/52 females and 79 Caucasians/28 African Americans/5 other with a mean waiting time of 16 months; 75 patients (66%) received kidneys from expanded criteria donors (ECDs) and 14 received dual KTs. Delayed graft function occurred in 27% and influenced graft but not patient survival. With a mean follow-up of 68 months, patient survival was 59% and uncensored kidney graft survival was 47%. Three year and death-censored kidney graft survival rates were 76% and 74%, respectively. Outcomes were similar in patients < or ≥ 75 years. Of 60 graft losses, death with a functioning graft (DWFG) accounted for 41 (68%). Of 46 deaths, 72% were due to cardio/cerebrovascular events, infection, or malignancy. At present, 54 of the 66 surviving patients (81.8%) have functioning grafts. The incidences of acute rejection and major infection were 14% and 45%, respectively. Conclusions: Advanced recipient age has a modest effect on medium-term outcomes in appropriately selected elderly patients using predominantly ECD kidneys, which may not be appropriate for younger patients. However, medium-term outcomes are largely influenced by a higher incidence of DWFGs in the elderly, suggesting that matching strategies for kidney and patient longevity are warranted.

4-(4-Nitro-phen-oxy)butanol.

The crystal structure of the title compound, C10H13NO4, features intermolecular O—H⋯O(nitro) hydrogen bonding, which links molecules into supramolecular chains running parallel to the bc diagonal. There is also π–π stacking between 4-nitrophenyl groups, the interplanar distance between the nitrobenzene rings being 3.472 (2) Å.

Study on thermal, spectroscopic and electrochemical behavior of some ferrocene-containing organometallic polyesteramides and their siloxane-based block copolymers

The thermal, spectroscopic and electrochemical behavior of some novel ferrocene-containing polyesteramides and their siloxane-based block copolymers are described in the present study. The thermal properties of the organometallic materials were investigated by thermogravimetric analysis (TGA) and compared with their terephthaloyl- and isophthaloyl-based organic analogues. The energies of activation of pyrolysis for the polymeric materials were calculated using Horowitz and Metzger method. The spectroscopic and electrochemical properties of the organometallic polymeric materials were examined by means of UV-visible (UV) and cyclic voltammetric (CV) studies. The interactions of these materials with ds.DNA (extracted from chicken blood) were also investigated.

4,4'-(Hexane-1,6-diyldi-oxy)dianiline.

The complete molecule of the title compound, C18H24N2O2, is generated by a crystallographic inversion centre. The torsion angles in the hexamethylene chain are consistent with an antiperiplanar conformation, whereas the conformation of the O—CH2—CH2—CH2 unit is gauche. The three-dimensional crystal packing is stabilized by N—H⋯O and N—H⋯N hydrogen bonding.