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Biomedical subjects

P John

Publications and source records attributed to P John.

At least 19 recordsLinked to original sources
PubMed2006

Blind placements of peripherally inserted antecubital central catheters: initial catheter tip position in relation to carina.

BACKGROUND: We investigated how often blind placement of peripherally inserted central catheters (PICCs) through the antecubital veins results in a correct tip location in relation to carina and evaluated the inter-observer agreement in locating the tip of PICCs in plain radiography with digital imaging. METHODS: In this study, 202 suitable chest radiographs with PICCs out of 803 patients were identified. An initial audit on the tip of these catheters in relation to carina was done by a consultant anaesthetist and was recorded as the first observer. The same sets of CXRs were examined by a consultant radiologist and the tips were identified and recorded as the second observer. Inter-observer agreement was assessed. RESULTS: In 75 of 202 (37%), PICCs had a central tip location in relation to the carina. Fifty-five of 131 (42%) right-sided catheters had a central location compared with 20 of 71 (28%) of the left-sided catheters. The tip position for right-sided catheters was most frequently centrally located whereas the tip for left-sided catheters was most commonly positioned in the ipsilateral innominate vein. There was excellent agreement between the observers in reporting the tip of PICCs at all positions (kappa=0.87) including central locations (kappa=0.83). CONCLUSIONS: Right antecubital PICCs are more likely to be placed in the central location in relation to the carina. PICCs inserted through the left antecubital veins need to be pushed further down to aim for a central location. Inter-observer variability in identifying the tip of PICCs is least with the introduction of digital imaging.

Catheterization, Central Venous↗
PubMed2006

Management of end-stage central venous access in children referred for possible small bowel transplantation.

UNLABELLED: The 3-year survival after small bowel transplantation (SBTx) has improved to between 73% and 88%. Impaired venous access for parenteral nutrition can be an indication for SBTx in children with chronic intestinal failure. AIM: To report our experience in management of children with extreme end-stage venous access. SUBJECTS: The study consisted of 6 children (all boys), median age of assessment 27 months (range, 13-52 months), diagnosed with total intestinal aganglionosis (1), protracted diarrhea (1), and short bowel syndrome (4), of which gastroschisis (2) and malrotation with midgut volvulus (2) were the causes. All had a documented history of more than 10 central venous catheter insertions previously. All had venograms, and 1 child additionally had a magnetic resonance angiogram to evaluate venous access. Five of 6 presented with thrombosis of the superior vena cava (SVC) and/or inferior vena cava. METHODS: Venous access was reestablished as follows: transhepatic venous catheters (5), direct intra-atrial catheter via midline sternotomy (4), azygous venous catheters (2), dilatation of left subclavian vein after passage of a guide wire and then placing a catheter to reach the right atrium (1), radiological recanalization of the SVC and placement of a central venous catheter in situ (1), and direct puncture of SVC stump(1). Complications included serous pleural effusion after direct intra-atrial line insertion, which resolved after chest drain insertion (1), displacement of transhepatic catheter needing repositioning (2), and SVC stent narrowing requiring repeated balloon dilatation. OUTCOME: Four children with permanent intestinal failure on assessment were offered SBTx, 3 of which were transplanted and were established on full enteral nutrition; the family of 1 child declined the procedure. In the remaining 2 children in whom bowel adaptation was still a possibility, attempts were made to provide adequate central venous access as feeds and drug manipulations were undertaken. One of them received liver and SBTx nearly 3 years after presenting with end-stage central venous access, because attempts to achieve independence from parenteral nutrition had failed. The other child died immediately after a transhepatic venous catheter placement, possibly from a nutritional depletion syndrome as no physical cause of death was found. Direct intra-atrial catheters in transplanted children proved to be adequate for the management of uncomplicated transplantation, although the usual infusion protocol had to be modified considerably, and the lack of access would have been critical if massive blood transfusion had been required during the transplant procedure. CONCLUSION: It was possible to reestablish central venous access in all cases. However, this was time consuming and difficult to assemble a skilled team consisting of one of more: surgeon, cardiologist, interventional radiologist, and transplant anesthetist. Small bowel transplantation is easier and safer with adequate central venous access, and we advocate liaison with an SBTx center at an early stage.

Catheterization, Central Venous↗
PubMed2006

Ectodermal dysplasia of hair and nail type: mapping of a novel locus to chromosome 17p12-q21.2.

BACKGROUND: Ectodermal dysplasias (EDs) describe a large and complex group of disorders characterized by abnormal development of the skin and appendages (hair, nails, teeth and sweat glands). Of the approximately 200 different EDs, about 30 have been studied at the molecular level. In an effort to understand the molecular bases of ED of hair and nail type, we studied a Pakistani consanguineous family with multiple affected individuals. OBJECTIVES: To localize the gene responsible for the autosomal recessive form of ED of hair and nail type. METHODS: Genotyping of nine members of the family, including five affected and four normal individuals was performed using microsatellite markers mapping to candidate regions, harbouring genes involved in related phenotypes. Five epithelial keratin genes located in the candidate region were sequenced to identify the pathogenic mutation. RESULTS: We mapped the disease locus to a 24.2-cM interval flanked by markers D17S839 and D17S1299 on chromosome 17p12-q21.2 (Z(max) = 4.4). DNA sequencing of five epithelial keratin candidate genes, present in the disease locus, did not reveal any pathogenic mutation in the affected individuals. CONCLUSIONS: The gene for ED of hair and nail type has been mapped to chromosome 17p12-q21.2 in a Pakistani consanguineous family. Failure to detect mutations in epithelial keratin genes suggests that the mutation may lie either in regulatory regions of one of the epithelial keratin genes or in another unknown gene, located in the linkage interval, with a possible role in the development of ectodermal appendages.

Chromosome Mapping↗
PubMed2006

The mapping of DFNB62, a new locus for autosomal recessive non-syndromic hearing impairment, to chromosome 12p13.2-p11.23.

Autosomal recessive non-syndromic hearing impairment (ARNSHI) is the most common form of prelingual inherited hearing impairment (HI). Here is described the mapping of a novel ARNSHI locus in a consanguineous Pakistani family with profound congenital HI. Two-point and multipoint linkage analyses were performed for the genome scan and fine mapping markers. Haplotypes were constructed to determine the region of homozygosity. At theta = 0, the maximum two-point LOD score of 4.0 was obtained at marker AAC040. A maximum multipoint LOD score of 5.3 was derived at marker D12S320, with the three-unit support interval demarcated by D12S89 and D12S1042. The region of homozygosity is flanked by markers D12S358 and D12S1042, which corresponds to 22.4 cM according to the Rutgers combined linkage-physical map of the human genome and spans 15.0 Mb on the sequence-based physical map. A novel ARNSHI locus DFNB62 was mapped to chromosome 12p13.2-p11.23. DFNB62 represents the second ARNSHI locus to map to chromosome 12.

Chromosomes, Human, Pair 12↗
PubMed2006

A novel locus for alopecia with mental retardation syndrome (APMR2) maps to chromosome 3q26.2-q26.31.

Congenital alopecia may occur either alone or in association with ectodermal and other abnormalities. On the bases of such associations, several different syndromes featuring congenital alopecia can be distinguished. Alopecia with mental retardation syndrome (APMR) is a rare autosomal recessive disorder, clinically characterized by total or partial hair loss and mental retardation. In the present study, a five-generation Pakistani family with multiple affected individuals with APMR was ascertained. Patients in this family exhibited typical features of APMR syndrome. The disease locus was mapped to chromosome 3q26.2-q26.31 by carrying out a genome scan followed by fine mapping. A maximum two-point logarithm of odds (LOD) score of 2.93 at theta=0.0 was obtained at markers D3S3053 and D3S2309. Multipoint linkage analysis resulted in a maximum LOD score of 4.57 with several markers, which supports the linkage. The disease locus was flanked by markers D3S1564 and D3S2427, which corresponds to 9.6-cM region according to the Rutgers combined linkage-physical map of the human genome (build 35) and contains 5.6 Mb. The linkage interval of the APMR locus identified here does not overlap with the one described previously; therefore, this locus has been designated as APMR2.

Alopecia↗
PubMed2005

The mechanism of bacterial indigo reduction.

The reduction of water-insoluble indigo by the recently isolated moderate thermophile, Clostridium isatidis, has been studied with the aim of developing a sustainable technology for industrial indigo reduction. The ability to reduce indigo was not shared with C. aurantibutyricum, C. celatum and C. papyrosolvens, but C. papyrosolvens could reduce indigo carmine (5,5'-indigosulfonic acid), a soluble indigo derivative. The supernatant from cultures of C. isatidis, but not from cultures of the other bacteria tested, decreased indigo particle size to one-tenth diameter. Addition of madder powder, anthraquinone-2,6-disulfonic acid, and humic acid all stimulated indigo reduction by C. isatidis. Redox potentials of cultures of C. isatidis were about 100 mV more negative than those of C. aurantibutyricum, C. celatum and C. papyrosolvens, and reached -600 mV versus the SCE in the presence of indigo, but potentials were not consistently affected by the addition of the quinone compounds, which probably act by modifying the surface of the bacteria or indigo particles. It is concluded that C. isatidis can reduce indigo because (1) it produces an extracellular factor that decreases indigo particle size, and (2) it generates a sufficiently reducing potential.

Biodegradation, Environmental↗
PubMed2004

A traumatic intra-renal pseudo-aneurysm in a child.

Intra-renal pseudo-aneurysms after penetrating renal trauma have not been reported in children. We report a case of a 9-year-old girl who presented with gross haematuria 2 weeks following renal exploration for a penetrating injury. The diagnosis of intra-renal pseudoaneurysm was made by Doppler ultrasound and was successfully treated by selective arterial embolisation.

Accidental Falls↗
PubMed2004

Characterization of high-level aminoglycoside-resistant enterococci in Kuwait hospitals.

This study investigated the distribution of genes for aminoglycoside-modifying enzymes (AME) and the genetic relatedness of high-level aminoglycoside-resistant enterococci isolated in Kuwait hospitals. A total of 117 enterococci, consisting of 109 Enterococcus faecalis, seven Enterococcus faecium, and one Enterococcus casseliflavus were studied. The MICs of gentamicin, kanamycin, amikacin, tobramycin, and streptomycin were determined by agar dilution and the genes encoding the AAC(6')- APH(2"), ANT(4'), APH(3'), APH (2")-Ib, APH (2")-Ic, APH (2")-Id, and ANT(6) enzymes were amplified by PCR. They were typed by pulsed-field gel electrophoresis (PFGE). Filter mating was used to transfer gentamicin resistance determinants. They were all resistant to kanamycin (MIC 2000 mg/L). Fifty-five isolates were resistant to gentamicin (MIC 500 mg/L), 72 were resistant to tobramycin (MIC 64 mg/L), 115 were resistant to amikacin (MIC 64 mg/L), and 97 were resistant to streptomycin (MIC 1000 mg/L). The aac(6')-Ie-aph(2")-Ia was detected in all isolates with gentamicin MIC 500 mg/L and in 15 isolates with gentamicin MIC 256 mg/L. The aph(3')-IIIa gene was detected in 101 isolates, whereas the ant(6')-Ia gene was detected in 85 of the 97 streptomycin-resistant isolates with MIC 1000 mg/L. The aac(6')-Ii gene was detected only in the seven E. faecium isolates. None of them contained ant(4')-Ia, aph(2")-Ib, aph(2")-Ic and aph(2")-Id. PFGE revealed heterogeneous patterns with no dominant clone. The results demonstrated that AME are common in aminoglycoside-resistant enterococci isolated in Kuwait. However, the absence of a dominant clone suggests that they acquired high-level aminoglycoside independently.

Aminoglycosides↗
PubMed2003

Meso-portal bypass in children with portal vein thrombosis: rapid increase of the intrahepatic portal venous flow after direct portal hepatic reperfusion.

BACKGROUND/PURPOSE: In children with portal vein (PV) thrombosis, hepatopetal portal flow can be restored by an innovative surgical procedure, the meso-portal-bypass (MPB), if the umbilical portion of the intrahepatic left PV and the superior mesenteric vein are patent. This is associated with resolution of symptoms related to extrahepatic portal hypertension (EHPH). However, no data are available yet on intrahepatic hemodynamic changes after MPB. The aim of this study was to evaluate morphologic adaptation and flow characteristics of the intrahepatic PV branches (ihPVb) after MPB. METHODS: Prospective follow-up Doppler scans of the ihPVb were performed at 0.5 to 1, 3 to 6 and 12 months after MPB in 13 consecutive patients (2000-2002) and compared with preoperative findings. RESULTS: Only small ihPVb were detected preoperatively on Doppler in 8 of 13 cases. Postoperatively (median follow up 12; range, 6 to 24 months), all 13 patients had patent MPB with hepatopetal flow, and ihPVb were easy to detect with satisfactory vessel diameters and flow velocities. CONCLUSIONS: The preoperatively small ihPVb increase rapidly in diameter and hepatopetal flow velocity in patients benefiting from MPB. This correlates well with progressive resolution of their symptoms related to EHPH and reflects rapid adaptation of ihPVb.

Adolescent↗
PubMed2003

Mutant alleles at the rugosus loci in pea affect seed moisture sorption isotherms and the relations between seed longevity and moisture content.

Pea (Pisum sativum L.) mutant near-isogenic lines (RRrbrb, rrRbRb, rrrbrb) with lower starch but higher lipid contents, brought about by lesions in the starch biosynthetic pathway, had seed moisture sorption isotherms displaced below that of the wild type (RRRbRb). The negative logarithmic relationship between seed longevity and seed storage moisture content (%, f.wt basis), determined in hermetic storage at 65 degrees C, also differed: longevity in the mutant near-isogenic lines was poorer and less sensitive to moisture content than in the wild type (i.e. C(W) was lower). The low-moisture-content limit (m(c)) to this relation also differed, being lower in the mutant near-isogenic lines (5.4-5.9%) than in the wild type (6.1%). In contrast, all four near-isogenic lines showed no difference (P >0.25) in the negative semi-logarithmic relationship between equilibrium relative humidity (ERH) and seed longevity. It is concluded that the effect of these alleles at the r and rb loci on seed longevity was largely indirect; a consequence of their effect on seed composition and hence on moisture sorption isotherms. However, this explanation could not be invoked at moisture contents below m(c) where differences in longevity remained substantial (RRRbRb double that of rrrbrb). Hence, these mutant alleles affected seed longevity directly at very low moisture contents.

Alleles↗
PubMed2003

[Radiation doses deriving from patients treated with (166)Ho-ferric hydroxide].

AIM: To estimate radiation doses deriving from patients treated with (166)Ho ferric hydroxide. METHODS: For radiation synoviorthesis about 900 +/- 100 MBq (166)Ho ferric hydroxide was injected into the knee joint of 16 patients. To estimate the radiation exposure of persons in the neighbourhood of the patients measurements of the dose rates were performed at 0.5 m, 1 m and 2 m distance of the treated joint 10 min after tracer injection. Measurements were carried out with and without radiation protection devices of the syringe. RESULTS: The initial values of the dose rate were 11.9 micro Sv/h at 0.5 m, 3.5 micro Sv/h at 1 m and 1 micro Sv/h at 2 m distance, respectively. The whole body doses were 2.9 micro Sv for the physician and 4.6 micro Sv for the technologist. The finger doses for the technologist and the physician were ranging from 65 to 111 micro Sv. After discharge at home other persons might receive 118 micro Sv. CONCLUSION: Our results, under very strict assumptions, clearly demonstrate that the calculated radiation exposure to medical and non medical personnel is well below the maximum annual dose limit. The use of any additional radiation protection device as syringe shielding does not significantly lower radiation exposure.

Fingers↗
PubMed2002

Study of the structure of passivated vanadium-titanium alloys and their semiconductor properties.

The possibility of investigating the photocurrent behavior and structure of electrochemically prepared passive films on metallic titanium and on binary vanadium-titanium alloys has been demonstrated. The semiconductor properties were characterized by measuring the dependence of the photocurrent on the wavelength of the incident light and on the electrode potential. The results showed the oxide layers to be n-type semiconductors with a bandgap between 2.6 and 3.3 eV and a flatband potential of approximately -300 to +400 mV (relative to the SCE). The results were interpreted in terms of the corrosion characteristics of the materials. XPS measurements on pure vanadium and some alloys are presented. Several properties were used to characterize the passive surface of these materials. The V(2)O(5) and TiO(2) content decreases with increasing depth.

Journal Article↗
PubMed2002

Antibiotic resistance of enterococci isolated at a teaching hospital in Kuwait.

Enterococci isolated in a teaching hospital were studied for their resistance to different antibiotics. Minimum inhibitory concentrations to high-level aminoglycosides and glycopeptide antibiotics were determined by agar dilution and E-test methods respectively. Genes encoding aminoglycoside-modifying enzymes were detected by the polymerase chain reaction (PCR). 195 enterococci were isolated from urines (54.3%), wounds (16.4%), blood (10.2%), and miscellaneous sources (18.9%). They consisted of E. faecalis (88.7%), E. faecium (9.2%), E. casseliflavus (1.5%) and E. bovis (0.5%). None of the enterococci produced penicillinase but 3.5% of them were resistant to ampicillin. They were also resistant to high-level gentamicin (15.9%), kanamycin (22.0%), streptomycin (21.0%), tetracycline (65.1%), erythromycin (62.6%), ciprofloxacin (36.1%), chloramphenicol (26.1%), vancomycin (3.0%) and teicoplanin (2.0%). Most of the high-level aminoglycoside-resistant isolates contained genes coding the bifunctional aminoglycoside modifying enzymes AAC(6')-APH(2"), APH(3') and ANT(6') but not the ANT(4') enzyme. The results demonstrated a low prevalence of vancomycin resistance among Enterococci in this hospital.

Academic Medical Centers↗
PubMed2002

Benefits of early diagnosis and preemptive treatment of biliary tract complications after major blunt liver trauma in children.

BACKGROUND/PURPOSE: Nonoperative management of blunt liver trauma may delay diagnosis of related biliary complications leading to delayed surgical intervention and related morbidity. The aim of this study was to see whether technetium (tc) 99 trimethylbromo-im-indolacetic acid (TBIDA) nuclear scan would allow noninvasive early diagnosis of bile leak and pre-emptive management. METHODS: Retrospective analysis of the patient records and radiologic investigations of 7 patients admitted between April 1998 and December 2000 with "major" blunt liver trauma (parenchymal fracture of less than 4 cm on computed tomography [CT] scan or involving porta hepatis) and various types of biliary complications. Patients with or without early TBIDA diagnosis were compared. RESULTS: There were 7 patients. The first 2 patients were treated conventionally without TBIDA, and late diagnosis was associated with further related problems (sepsis, life-threatening hemorrhage in both cases) and prolonged hospital stay. The subsequent 5 consecutive patients benefited from early diagnosis (TBIDA scan, 2 to 4 days after trauma), and preemptive management was done (tailored to each case). There was no further or related morbidity. All 7 patients currently are alive and well. CONCLUSIONS: A TBIDA nuclear medicine scan was efficient in providing an early diagnosis of biliary leakage, thus, allowing adequate preemptive management. In turn, this may have helped avoid related added morbidity compared with cases of late diagnosis. Early TBIDA scan should be performed routinely when the initial CT scan confirms liver trauma graded as "major."

Adolescent↗