Percutaneous nephrostomy catheter-related infections in patients with gynaecological cancers: a multidisciplinary algorithmic approach

BACKGROUND

Percutaneous nephrostomy catheters (PCNs) are commonly utilized in patients with gynaecological cancers due to intrinsic or extrinsic urinary obstruction. Unfortunately, these foreign medical devices may be associated with several infectious complications, including: pyelonephritis, renal abscess, and bacteraemia, which may lead to further delay of life-saving cancer therapy.

AIM

To evaluate the performance of our multidisciplinary algorithm for diagnosis and treatment of PCN-related infections (PCNIs) and identify risk factors for recurrent urinary device-related infections.

METHODS

Patients with gynaecological cancers having PCNIs were prospectively evaluated at our institution from July 2019 to September 2021. All patients were managed by our standardized algorithm and followed-up until reinfection or routine PCN exchange.

FINDINGS

Of 100 consecutive patients with PCNIs, 74 had adequate follow-up, and were analysed in three groups according to clinical outcome: reinfection with the same organism (26%), reinfection with a different organism (23%), and no reinfection (51%). Their median age was 54 years, and the most common cancers were cervical (65%), and ovarian (19%) with 53% being metastatic. The most frequently recovered micro-organisms were Pseudomonas (32%), Enterococcus (27%), and Escherichia (24%) species. The main risk factors for recurrent PCNI with the same organism were pelvic radiation therapy (P=0.032), pelvic fistulas (P=0.014), and a PCNI with the same pathogen within the previous year (P = 0.012).

CONCLUSIONS

Our algorithm has allowed for accurate diagnosis, staging, and treatment of and identification of several key risk factors for recurrent PCNIs. These results may lead to further preventive measures for these infections.

Hand eczema in children referred for patch testing: North American Contact Dermatitis Group Data, 2000-2016

BACKGROUND

Little is known about the aetiologies and relevant allergens in paediatric patients with hand eczema (HE).

OBJECTIVES

To characterize the aetiologies and determine the proportion of positive and currently relevant allergens in children/adolescents (age < 18 years) with HE referred for patch testing.

METHODS

A retrospective analysis (2000-2016) of North American Contact Dermatitis Group data was performed.

RESULTS

Of 1634 paediatric patients, 237 (14·5%) had involvement of the hands. Final physician diagnoses included allergic contact dermatitis (49·4%), atopic dermatitis (37·1%) and irritant contact dermatitis (16·9%). In multivariable logistic regression models, employment was the only association with increased odds of any HE or primary HE. Children with HE vs. those without HE had similar proportions of positive patch tests (56·1% vs. 61·7%; χ² -test, P = 0·11). The five most common currently relevant allergens were nickel, methylisothiazolinone, propylene glycol, decyl glucoside and lanolin. In multivariable logistic regression models of the top 20 relevant allergens, HE was associated with significantly higher odds of currently relevant reactions to lanolin, quaternium-15, Compositae mix, thiuram mix, 2-mercaptobenzathiazole and colophony. The allergens with the highest mean significance-prevalence index number were methylisothiazolinone, carba mix, thiuram mix, nickel and methylchloroisothiazolinone/methylisothiazolinone.

CONCLUSIONS

Children with HE who were referred for patch testing had a high proportion of positive patch tests, which was similar to the proportion found in children without HE. Children with HE had a distinct and fairly narrow profile of currently relevant allergens.

Clinical outcomes of patients with adenocarcinoma in situ of the cervix treated by conization

OBJECTIVE

To describe the clinical outcomes of histologically confirmed adenocarcinoma in situ (AIS) of the cervix treated with cervical conization.

MATERIALS AND METHODS

A retrospective chart review of patients with histologically confirmed AIS from July 1998 to February 2011 included 52 patients. The rates of residual disease in subsequent excisions, the clinical recurrence rate, the average disease-free interval, and risk of progression to adenocarcinoma were described. The clinical outcomes of patients treated with cold knife cone (CKC) and loop electrosurgical excisional procedure (LEEP) were compared.

RESULTS

Fifteen LEEPs and 37 CKC procedures were performed as initial treatment and 26 patients (50%) had positive margins. There was no significant difference in rate of positive margins between LEEP and CKC (40% vs. 54%, respectively. p = 0.55). LEEPs and CKCs resulted in similar volumes of cervical tissue resected (4.98 cm3 vs. 5.04 cm3, p = 0.40). Of patients with positive margins, ten underwent immediate hysterectomy, six underwent a second cone biopsy, seven were managed expectantly, and four were lost to follow up. Residual AIS was found in 47% (eight of 17) of repeat cone biopsy and hysterectomy specimens performed for positive cone margins. Of the 26 patients with negative cone margins, no residual or recurrent disease was found after an average follow-up of 32 months.

CONCLUSIONS

A positive surgical margin was associated with residual disease in 47% of patients with AIS treated with conization. No patient with negative cone margins had recurrent or progressive disease. Cervical conization with negative margins appears to be a safe treatment option for patients with AIS but requires further investigation. CKC and LEEP were equally efficacious treatments in our study population.

Oral vaccination and protection of red foxes (Vulpes vulpes) against rabies using ONRAB, an adenovirus-rabies recombinant vaccine

Twenty-seven red foxes (Vulpes vulpes) were each offered a bait containing ONRAB, a recombinant oral rabies vaccine that uses a human adenovirus vector to express the immunogenic rabies virus glycoprotein; 10 controls received no vaccine baits. Serum samples collected from all foxes before treatment, and each week post-treatment for 16 weeks, were tested for the presence of rabies virus neutralizing antibody (RVNA). In the bait group, a fox was considered a responder to vaccination if serum samples from 3 or more consecutive weeks had RVNA ≥0.5 IU/ml. Using this criterion, 79% of adult foxes (11/14) and 46% of juveniles (6/13) responded to vaccination with ONRAB. Serum RVNA of adults first tested positive (≥0.5 IU/ml) between weeks 1 and 3, about 4 weeks earlier than in juveniles. Adults also responded with higher levels of RVNA and these levels were maintained longer. Serum samples from juveniles tested positive for 1-4 consecutive weeks; in adults the range was 2-15 weeks, with almost half of adults maintaining titres above 0.5 IU/ml for 9 or more consecutive weeks. Based on the kinetics of the antibody response to ONRAB, the best time to sample sera of wild adult foxes for evidence of vaccination is 7-11 weeks following bait distribution. Thirty-four foxes (25 ONRAB, 9 controls) were challenged with vulpine street virus 547 days post-vaccination. All controls developed rabies whereas eight of 13 adult vaccinates (62%) and four of 12 juvenile vaccinates (33%) survived. All foxes classed as non-responders to vaccination developed rabies. Of foxes considered responders to vaccination, 80% of adults (8/10) and 67% of juveniles (4/6) survived challenge. The duration of immunity conferred to foxes would appear adequate for bi-annual and annual bait distribution schedules as vaccinates were challenged 1.5 years post-vaccination.

Principles of human locomotion: a review

In this article the principles of human locomotion are revisited and reviewed. This has been done in the framework of two European projects, where the elicitation of these mechanisms inform, on the one hand, the design of artificial bipedal walkers (H2R), and on the other hand the design of lower limb exoskeletons (BETTER) for rehabilitation of gait in post-stroke patients. Passive dynamics emerging from the morphology of the human musculoskeletal system, reflexes as stabilization mechanisms, modular control of movement as well as supra-spinal control of gait are reviewed to get insight on how these mechanisms can be used to explain human locomotion.

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

Pragmatic approach to the clinical work-up of patients with putative allergic disease to metallic orthopaedic implants before and after surgery

Allergic complications following insertion of metallic orthopaedic implants include allergic dermatitis reactions but also extracutaneous complications. As metal-allergic patients and/or surgeons may ask dermatologists and allergologists for advice prior to planned orthopaedic implant surgery, and as surgeons may refer patients with complications following total joint arthroplasty for diagnostic work-up, there is a continuous need for updated guidelines. This review presents published evidence for patch testing prior to surgery and proposes tentative diagnostic criteria which clinicians can rely on in the work-up of patients with putative allergic complications following surgery. Few studies have investigated whether subjects with metal contact allergy have increased risk of developing complications following orthopaedic implant insertion. Metal allergy might in a minority increase the risk of complications caused by a delayed-type hypersensitivity reaction. At present, we do not know how to identify the subgroups of metal contact allergic patients with a potentially increased risk of complications following insertion of a metal implant. We recommend that clinicians should refrain from routine patch testing prior to surgery unless the patient has already had implant surgery with complications suspected to be allergic or has a history of clinical metal intolerance of sufficient magnitude to be of concern to the patient or a health provider. The clinical work-up of a patient suspected of having an allergic reaction to a metal implant should include patch testing and possibly in vitro testing. We propose diagnostic criteria for allergic dermatitis reactions as well as noneczematous complications caused by metal implants.

Voluntary ankle flexor activity and adaptive coactivation gain is decreased by spasticity during subacute spinal cord injury

Although spasticity has been defined as an increase in velocity-dependent stretch reflexes and muscle hypertonia during passive movement, the measurement of flexor muscle paresis may better characterize the negative impact of this syndrome on residual motor function following incomplete spinal cord injury (iSCI). In this longitudinal study Tibialis Anterior (TA) muscle paresis produced by a loss in maximal voluntary contraction during dorsiflexion and ankle flexor muscle coactivation during ramp-and-hold controlled plantarflexion was measured in ten patients during subacute iSCI. Tibialis Anterior activity was measured at approximately two-week intervals between 3-5 months following iSCI in subjects with or without spasticity, characterized by lower-limb muscle hypertonia and/or involuntary spasms. Following iSCI, maximal voluntary contraction ankle flexor activity was lower than that recorded from healthy subjects, and was further attenuated by the presence of spasticity. Furthermore the initially high percentage value of TA coactivation increased at 75% but not at 25% maximal voluntary torque (MVT), reflected by an increase in TA coactivation gain (75%/25% MVT) from 2.5+/-0.4 to 7.5+/-1.9, well above the control level of 2.9+/-0.2. In contrast contraction-dependent TA coactivation gain decreased from 2.4+/-0.3 to 1.4+/-0.1 during spasticity. In conclusion the adaptive increase in TA coactivation gain observed in this pilot study during subacute iSCI was also sensitive to the presence of spasticity. The successful early diagnosis and treatment of spasticity would be expected to further preserve and promote adaptive motor function during subacute iSCI neurorehabilitation.

Estrogenic pyrethroid pesticides regulate expression of estrogen receptor transcripts in mouse Sertoli cells differently from 17beta-estradiol

Studies suggested that exposure to agricultural pesticides may affect male fertility. Pyrethroids are widely used pesticides due to their insecticidal potency and low mammalian toxicity. A recombinant yeast assay system incorporating the human alpha-estrogen receptor was used to analyze the estrogenicity of a range of readily available pyrethroid pesticides. The commercial product Ripcord Plus showed estrogenic activity by this assay. To determine whether pyrethroid compounds might exert an effect on male fertility, mouse Sertoli cells were exposed in vitro to the endogenous estrogen, 17beta-estradiol, and selected estrogenic pyrethroids. Following exposure, transcript levels of the alpha- and beta-estrogen receptors were assessed. Exposure of Sertoli cells to the pyrethroid compounds, both at high and at low published serum concentrations, affected the expression of the two estrogen receptors; however, the influence on estrogen receptor gene expression was different from the effect from exposure to 17beta-estradiol. These results from our model systems suggest that (1) estrogenic pyrethroid pesticides affect the estrogen receptors, and therefore potentially the endocrine system, in a different manner from that of endogenous estrogen, and (2) should cells in the male testes be exposed to pyrethroid pesticides, male fertility may be affected through molecular mechanisms involving estrogen receptors.

Role of IL-15 in spinal cord and sciatic nerve after chronic constriction injury: regulation of macrophage and T-cell infiltration

The release of inflammatory mediators from immune and glial cells either in the peripheral or CNS may have an important role in the development of physiopathological processes such as neuropathic pain. Microglial, then astrocytic activation in the spinal cord, lead to chronic inflammation, alteration of neuronal physiology and neuropathic pain. Standard experimental models of neuropathic pain include an important peripheral inflammatory component, which involves prominent immune cell activation and infiltration. Among potential immunomodulators, the T-cell cytokine interleukin-15 (IL-15) has a key role in regulating immune cell activation and glial reactivity after CNS injury. Here we show, using the model of chronic constriction of the sciatic nerve (CCI), that IL-15 is essential for the development of the early inflammatory events in the spinal cord after a peripheral lesion that generates neuropathic pain. IL-15 expression in the spinal cord was identified in both astroglial and microglial cells and was present during the initial gliotic and inflammatory (NFkappaB) response to injury. The expression of IL-15 was also identified as a cue for macrophage and T-cell activation and infiltration in the sciatic nerve, as shown by intraneural injection of the cytokine and activity blockage approaches. We conclude that the regulation of IL-15 and hence the initial events following its expression after peripheral nerve injury could have a future therapeutic potential in the reduction of neuroinflammation.

A "Queen of Hearts" trial of organ markets: why Scheper-Hughes's objections to markets in human organs fail

Nancy Scheper-Hughes is one of the most prominent critics of markets in human organs. Unfortunately, Scheper-Hughes rejects the view that markets should be used to solve the current (and chronic) shortage of transplant organs without engaging with the arguments in favour of them. Scheper-Hughes's rejection of such markets is of especial concern, given her influence over their future, for she holds, among other positions, the status of an adviser to the World Health Organization (Geneva) on issues related to global transplantation. Given her influence, it is important that Scheper-Hughes's moral condemnation of markets in human organs be subject to critical assessment. Such critical assessment, however, has not generally been forthcoming. A careful examination of Scheper-Hughes's anti-market stance shows that it is based on serious mischaracterisations of both the pro-market position and the medical and economic realities that underlie it. In this paper, the author will expose and correct these mischaracterisations and, in so doing, show that her objections to markets in human organs are unfounded.

Black markets, transplant kidneys and interpersonal coercion

One of the most common arguments against legalising markets in human kidneys is that this would result in the widespread misuse that is present in the black market becoming more prevalent. In particular, it is argued that if such markets were to be legalised, this would lead to an increase in the number of people being coerced into selling their kidneys. Moreover, such coercion would occur even if markets in kidneys were regulated, for those subject to such coercion would not be able to avail themselves of the legal protections that regulation would afford them. Despite the initial plausibility of this argument, there are three reasons to reject it. Firstly, the advantages of legalising markets in human kidneys would probably outweigh its possible disadvantages. Secondly, if it is believed that no such coercion can ever be tolerated, markets in only those human kidneys that fail to do away with coercion should be condemned. Finally, if coercion is genuinely opposed, then legalising kidney markets should be supported rather than opposed, for more people would be coerced (ie, into not selling) were such markets to be prohibited.

A genomic view of the sea urchin nervous system

The sequencing of the Strongylocentrotus purpuratus genome provides a unique opportunity to investigate the function and evolution of neural genes. The neurobiology of sea urchins is of particular interest because they have a close phylogenetic relationship with chordates, yet a distinctive pentaradiate body plan and unusual neural organization. Orthologues of transcription factors that regulate neurogenesis in other animals have been identified and several are expressed in neurogenic domains before gastrulation indicating that they may operate near the top of a conserved neural gene regulatory network. A family of genes encoding voltage-gated ion channels is present but, surprisingly, genes encoding gap junction proteins (connexins and pannexins) appear to be absent. Genes required for synapse formation and function have been identified and genes for synthesis and transport of neurotransmitters are present. There is a large family of G-protein-coupled receptors, including 874 rhodopsin-type receptors, 28 metabotropic glutamate-like receptors and a remarkably expanded group of 161 secretin receptor-like proteins. Absence of cannabinoid, lysophospholipid and melanocortin receptors indicates that this group may be unique to chordates. There are at least 37 putative G-protein-coupled peptide receptors and precursors for several neuropeptides and peptide hormones have been identified, including SALMFamides, NGFFFamide, a vasotocin-like peptide, glycoprotein hormones and insulin/insulin-like growth factors. Identification of a neurotrophin-like gene and Trk receptor in sea urchin indicates that this neural signaling system is not unique to chordates. Several hundred chemoreceptor genes have been predicted using several approaches, a number similar to that for other animals. Intriguingly, genes encoding homologues of rhodopsin, Pax6 and several other key mammalian retinal transcription factors are expressed in tube feet, suggesting tube feet function as photosensory organs. Analysis of the sea urchin genome presents a unique perspective on the evolutionary history of deuterostome nervous systems and reveals new approaches to investigate the development and neurobiology of sea urchins.

An overview of neurolaw for the clinician: what every potential witness should know

This article reviews the field of medical jurisprudence known as neurolaw which deals with the medicolegal ramifications of brain and spinal cord injuries. Placing emphasis upon how clinicians may work effectively with trial lawyers, it provides practical guidance to neurorehabilitation professionals who testify in personal injury cases.

Why primiparous mothers do not breastfeed in the United States: a national survey

AIM

To investigate primiparous women's primary reason for not breastfeeding.

METHODS

We used the 1995 National Survey of Family Growth to analyze the breastfeeding behaviors of a national probability sample of 6733 first-time US mothers, aged 15 to 44 y. Main outcome measures in this cross-sectional study were the reasons for never breastfeeding and reasons for stopping breastfeeding using closed-ended, multiple choice questions.

RESULTS

Most commonly, women did not breastfeed because they "preferred to bottle feed" (66.3%). The most common reason for stopping breastfeeding was that the child was "old enough to wean" (35.7%), although 15%, 34%, 54%, and 78% of those women had stopped breastfeeding by 3, 6, 9, and 12 mo, respectively. "Physical or medical problem" was reported by 14.9% of women who did not breastfeed and 26.9% of women who had stopped breastfeeding, making it the second most common reason for not breastfeeding in each group. There were significant differences across racial and ethnic groups.

CONCLUSION

Additional studies are needed to better understand why women "prefer to bottle feed", especially black women. Increasingly effective programs and policies to promote breastfeeding will logically follow. Since physical and medical problems are such common reasons both for never breastfeeding and for stopping breastfeeding, individual healthcare providers can have a significant impact on breastfeeding rates and duration.

GIS uses and constraints on diffusion in Eastern European and the former USSR

The authors examine the emerging uses of geographic information systems (GIS) in Eastern Europe and the countries that formerly were part of the USSR. "The paper, based on a communications survey, conference participation, and local sources, devotes particular attention to GIS applications in planning and services delivery and to variable rates of adoption of GIS technology in the region, as documented in a table of public-sector applications compiled by the authors. Factors limiting the utility of traditional innovation-diffusion models in understanding current patterns are identified."

[Traumatic injuries to the central nervous system and their repair]

DEVELOPMENT

Brain and spinal cord lesions have an increasing social and economic importance. Accidental trauma of various kinds is the main cause of mortality of children and young adults in developed countries. Only cardiac disease and cancer surpass the number of death caused by accidents and, examining the number of potential work years lost, CNS lesions surpass all other problems. Most brain and spinal cord injuries cause chronic incapacity and frequently occur to individuals under 45 years of age. Edema and other acute events can be efficiently treated and CNS lesions may not be mortal, but are incurable.

CONCLUSION

The final outcome of CNS injury depend on the area damaged and the extent of the lesion, but the best present therapies can offer is relief of the symptoms and rehabilitation. This review examines the present state of functional repair of experimental central nervous system trauma.

Is the capacity for optic nerve regeneration related to continued retinal ganglion cell production in the frog?

In the central nervous system of fish and frogs, some, but not all, axons can regenerate. Retinal ganglion cells are among those that can. The retinae of fish and frogs produce new retinal neurons, including ganglion cells, for months or years after hatching. We have evaluated the hypothesis that retinal axonal regeneration is obligatorily linked to continued production of new ganglion cells. We used bromodeoxyuridine immunocytochemistry to assess retinal neurogenesis in juvenile, yearling, and 10 year old Xenopus laevis. Retinal ganglion cell genesis was vigorous in the marginal retina of the juveniles, but in the yearlings and the 10 year olds, no new ganglion cells were produced there. Cellular proliferation in the central retina was evident at all three ages, but none of the cells produced centrally were in the ganglion cell layer. Regeneration was examined in vivo by cutting one optic nerve and then, weeks later, injecting the eye with tritiated proline. Autoradiographs of brain sections showed that the optic nerves of all three ages regenerated. Regeneration in vitro was assessed using retinal explants from frogs of all three ages. In all cases, the cultures produced neurites, with some age-specific differences in the patterns of outgrowth. We conclude that retinal axonal regeneration is not linked obligatorily to maintained neurogenesis.

Fragmentation of photomodified oligodeoxynucleotides adducted with metal ions in an electrospray-ionization ion-trap mass spectrometer

We report the effect of metal-ion adduction on the fragmentation of oligodeoxynucleotides (ODNs) bearing DNA photoproducts. When protons on backbone phosphates of ODNs are completely replaced with metal ions, cleavages occur readily within the photoproduct moiety, whereas those cleavages do not occur in photomodified ODNs in which the phosphates are associated with protons. For example, thymine/adenine (TA*) photoproducts revert to their undamaged precursors upon collisional activation, the pyrimidine(6-4)pyrimidone product and its Dewar valence isomer show a characteristic neutral loss of C4H3NO3, and dimeric adenine photoproducts show a distinctive loss of NH2CN from the adenine six-membered ring. The product-ion mass spectra of photodamaged ODNs that are adducted to metal ions are complementary in terms of structure information to those spectra of ODNs in which the phosphates are associated with protons. The results also demonstrate that the energy required for strand cleavages is higher for ODNs adducted with metal ions than that for ODNs bound with protons. Furthermore, the loss of a pyrimidine is more favorable than the loss of a purine in the fragmentation of ODNs associated with metal ions.

Comparative genomics provides evidence for an ancient genome duplication event in fish

There are approximately 25 000 species in the division Teleostei and most are believed to have arisen during a relatively short period of time ca. 200 Myr ago. The discovery of 'extra' Hox gene clusters in zebrafish (Danio rerio), medaka (Oryzias latipes), and pufferfish (Fugu rubripes), has led to the hypothesis that genome duplication provided the genetic raw material necessary for the teleost radiation. We identified 27 groups of orthologous genes which included one gene from man, mouse and chicken, one or two genes from tetraploid Xenopus and two genes from zebrafish. A genome duplication in the ancestor of teleost fishes is the most parsimonious explanation for the observations that for 15 of these genes, the two zebrafish orthologues are sister sequences in phylogenies that otherwise match the expected organismal tree, the zebrafish gene pairs appear to have been formed at approximately the same time, and are unlinked. Phylogenies of nine genes differ a little from the tree predicted by the fish-specific genome duplication hypothesis: one tree shows a sister sequence relationship for the zebrafish genes but differs slightly from the expected organismal tree and in eight trees, one zebrafish gene is the sister sequence to a clade which includes the second zebrafish gene and orthologues from Xenopus, chicken, mouse and man. For these nine gene trees, deviations from the predictions of the fish-specific genome duplication hypothesis are poorly supported. The two zebrafish orthologues for each of the three remaining genes are tightly linked and are, therefore, unlikely to have been formed during a genome duplication event. We estimated that the unlinked duplicated zebrafish genes are between 300 and 450 Myr. Thus, genome duplication could have provided the genetic raw material for teleost radiation. Alternatively, the loss of different duplicates in different populations (i.e. 'divergent resolution') may have promoted speciation in ancient teleost populations.

Use of a combined enzymatic digestion/ESI mass spectrometry assay to study the effect of TATA-binding protein on photoproduct formation in a TATA box

Recently, it was reported that TATA-binding protein (TBP) enhances (6-4) photoproduct formation in a TATA box under UVC irradiation [Aboussekhra and Thoma (1999) EMBO J. 18, 433-443]. The conclusions of that study were based on an indirect enzymatic assay that was not specific for (6-4) photoproducts. Herein we report the use of a recently developed coupled enzymatic digestion/mass spectrometry assay [Wang et al. (1999) Chem. Res. Toxicol. 12, 1077-1082] to identify unambiguously and quantify the photoproducts formed in a TATA box-containing dodecamer duplex sequence in the presence or absence of TBP binding. Exposure of the adenovirus major late promoter TATA box to a high dose of UVC irradiation in the absence of the C-terminal domain of yeast TBP leads to predominant formation of the cis-syn dimer within the T(4) tract, whereas exposure in the presence of TBP leads to almost exclusive formation of the (6-4) photoproduct. In contrast, the (6-4) product is not detected at high doses of UVB irradiation in the absence of TBP but is detected in the presence of TBP, although the cis-syn product predominates. When the products of UVB irradiation were subsequently exposed to a high dose of UVC irradiation in the presence of TBP, the (6-4) photoproduct again becomes nearly the exclusive photoproduct, indicating that the cis-syn dimer is being reversed to TT by UVC light. Both cis-syn and (6-4) photoproducts are formed in approximately equal amounts upon irradiation with small doses of UVC in the presence of TBP, but the fraction of (6-4) photoproduct increases with dose. Through the use of a TATA box containing a site-specifically deuterated thymine, it was found that (6-4) photoproducts formed most selectively at the second and third positions of the T(4) tract upon either UVB or UVC irradiation in the presence of TBP. By using the same substrate, it was found that UVC-induced TA formation was inhibited by TBP binding and that TA formation was greatest at the 5' end of the TATA sequence.

The ghost of selection past: rates of evolution and functional divergence of anciently duplicated genes

The duplication of genes and even complete genomes may be a prerequisite for major evolutionary transitions and the origin of evolutionary novelties. However, the evolutionary mechanisms of gene evolution and the origin of novel gene functions after gene duplication have been a subject of many debates. Recently, we compiled 26 groups of orthologous genes, which included one gene from human, mouse, and chicken, one or two genes from the tetraploid Xenopus and two genes from zebrafish. Comparative analysis and mapping data showed that these pairs of zebrafish genes were probably produced during a fish-specific genome duplication that occurred between 300 and 450 Mya, before the teleost radiation (Taylor et al. 2001). As discussed here, many of these retained duplicated genes code for DNA binding proteins. Different models have been developed to explain the retention of duplicated genes and in particular the subfunctionalization model of Force et al. (1999) could explain why so many developmental control genes have been retained. Other models are harder to reconcile with this particular set of duplicated genes. Most genes seem to have been subjected to strong purifying selection, keeping properties such as charge and polarity the same in both duplicates, although some evidence was found for positive Darwinian selection, in particular for Hox genes. However, since only the cumulative pattern of nucleotide substitutions can be studied, clear indications of positive Darwinian selection or neutrality may be hard to find for such anciently duplicated genes. Nevertheless, an increase in evolutionary rate in about half of the duplicated genes seems to suggest that either positive Darwinian selection has occurred or that functional constraints have been relaxed at one point in time during functional divergence.

Determination of photomodified oligodeoxynucleotides by exonuclease digestion, matrix-assisted laser desorption/ionization and post-source decay mass spectrometry

A fast method to detect and sequence photomodified oligodeoxynucleotides (ODNs) by exonuclease digestion and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is reported. Upon treatment of modified ODNs with both phosphodiesterase I and phosphodiesterase II, the digestion stops at the sites of photomodification. Post-source decay (PSD) of MALDI-produced ions from two enzymatic digestion end products distinguishes isomers such as 5'-d(T[cis-syn]TAAGC) and 5'-d(CGAAT[cis-syn]T), which have symmetrical or identical compositions at the 3' and 5' ends, respectively. Studies have also been done to follow the kinetics for enzyme degradation of photomodified ODNs. The calculated rate constants from a mathematical treatment of the time-dependent MALDI data clearly show that the enzymatic digestion rate slows as the enzyme approaches the modified site.

Nucleic acid triggered catalytic drug and probe release: a new concept for the design of chemotherapeutic and diagnostic agents

Recently, we described a new concept for the design of highly selective antiviral and anticancer chemotherapeutic agents that makes use of a disease-specific nucleic acid sequence to template the association of a prodrug with a catalyst which catalyzes the release of the drug. Herein, we report on the effect of mismatches, sterics, and electronics on the rate and specificity of drug and probe release in both two and three component model systems, and on the stability of the prodrug linker in human serum.

Bacterial growth in distribution systems: effect of assimilable organic carbon and biodegradable dissolved organic carbon

Two distribution systems, one treating water by ozonation and another treating water by nanofiltration in parallel with lime softening, were monitored for bacterial growth. Both systems kept disinfectant residuals such as chlorine and chloramine in their respective distribution systems. Bacterial growth was assessed by heterotrophic plate counts (HPC) on R2A agar. In the distribution systems fed by ozonated water, HPCs were correlated (R2 = 0.96) using an exponential model with the assimilable organic carbon (AOC) at each sampling site. Also, it was observed that ozonation caused a significant increase in the AOC concentration of the distribution system (over 100% increase) as well as a significant increase in the bacterial counts of the distribution system (average increase over 100%). The HPCs from the distribution systems fed by nanofiltration in parallel with lime-softening water also displayed an exponential correlation (R2 = 0.73) with an exponential model based on AOC. No significant correlation was found between bacteria growth on R2A agar and BDOC concentrations. Therefore, in agreement with previous work, bacterial growth in the distribution systems was found to correlate with AOC concentrations.

Patch testing discordance alert: false-negative findings with rubber additives and fragrances

From July 1996 through June 1998, the North American Contact Dermatitis Group evaluated 318 patients for suspected contact dermatitis by patch testing simultaneously with Finn Chambers and the T.R.U.E. Test allergen system. Discrepancies between the two systems were found in some of the results, particularly with fragrance and rubber allergens. These results suggest that positive reactions to fragrance, thiuram, and carba mix allergens may be missed if the T.R.U.E. Test is used alone.

Genome duplication, divergent resolution and speciation

What are the evolutionary consequences of gene duplication? One answer is speciation, according to a model initially called Reciprocal Silencing and recently expanded and renamed Divergent Resolution. This model shows how the loss of different copies of a duplicated gene in allopatric populations (divergent resolution) can promote speciation by genetically isolating these populations should they become reunited. Genome duplication events produce thousands of duplicated genes. Therefore, lineages with a history of genome duplication might have been especially prone to speciation via divergent resolution.

Simplified analysis of contaminant rejection during ground- and surface water nanofiltration under the information collection rule

A simple, closed-form analytical expression based on the homogenous solution diffusion model is derived for contaminant removal during nanofiltration (NF) of ground and surface water. Solute permeation and back-diffusion coefficients were used as fitting parameters to model rejection characteristics of four thin-film composite NF membranes under conditions typical of drinking water NF. Nonlinear fits of the model to experimental data suggests that the United States Environmental Protection Agency's (USEPA)'s Information Collection Rule protocol for bench-scale studies could be improved to obtain greater precision of the mass transfer coefficients. The model was found to fit rejection data for several water treatment contaminants including total organic carbon, precursors to total organic halide, four trihalomethanes and nine haloacetic acids containing chlorine and bromine, calcium and total hardness, alkalinity and conductivity. The simplified approach to mass transfer calculations from multisolute systems suggests that feed water recovery has a stronger influence on contaminant rejection than permeate flux. Evidence for coupled transport of divalent inorganic ions is also presented. Even though the model developed does not account for ion coupling and cannot be applied in a purely predictive mode, it can assist in the better design and interpretation of data obtained from site-specific pilot-scale water treatment NF studies conducted in support of plant design.

Translesion synthesis by yeast DNA polymerase zeta from templates containing lesions of ultraviolet radiation and acetylaminofluorene

In the yeast Saccharomyces cerevisiae, DNA polymerase zeta (Polzeta) is required in a major lesion bypass pathway. To help understand the role of Polzeta in lesion bypass, we have performed in vitro biochemical analyses of this polymerase in response to several DNA lesions. Purified yeast Polzeta performed limited translesion synthesis opposite a template TT (6-4) photoproduct, incorporating A or T with similar efficiencies (and less frequently G) opposite the 3' T, and predominantly A opposite the 5' T. Purified yeast Polzeta predominantly incorporated a G opposite an acetylaminofluorene (AAF)-adducted guanine. The lesion, however, significantly inhibited subsequent extension. Furthermore, yeast Polzeta catalyzed extension DNA synthesis from primers annealed opposite the AAF-guanine and the 3' T of the TT (6-4) photoproduct with varying efficiencies. Extension synthesis was more efficient when A or C was opposite the AAF-guanine, and when G was opposite the 3' T of the TT (6-4) photoproduct. In contrast, the 3' T of a cis-syn TT dimer completely blocked purified yeast Polzeta, whereas the 5' T was readily bypassed. These results support the following dual-function model of Polzeta. First, Polzeta catalyzes nucleotide incorporation opposite AAF-guanine and TT (6-4) photoproduct with a limited efficiency. Secondly, more efficient bypass of these lesions may require nucleotide incorporation by other DNA polymerases followed by extension DNA synthesis by Polzeta.

Comparison of patch test results with a standard series among white and black racial groups

BACKGROUND

Environmental, cultural, occupational, genetic, individual, and racial differences are important factors in the study of contact dermatitis. Some epidemiologic studies have compared overall sensitization rates among different racial groups, but similar data are lacking on individual allergens.

OBJECTIVE

Determine differences in sensitization rates between 2 racial groups in North America undergoing patch testing over a period of 4 years at the Cleveland Clinic Foundation (CCF), Ohio.

METHODS

Retrospective computer review of the standard screening tray results of 991 patients with an average age of 45.9 years consisting of 877 (88.5%) whites and 114 (11.5%) blacks.

RESULTS

Nickel sulfate and thiomersal (both 8.0%) and nickel sulfate and p-phenylenediamine (both 10.6%) were the 2 most common sensitizers among whites and blacks respectively. There was a statistically significant difference (P =.00599) in the sensitization rate for p-phenylenediamine in blacks (10.6%) compared with whites (4.5%). There were also statistically significant differences in sensitization rates for p-phenylenediamine (21.2%; P =.00005) and imidazolidinyl urea in petrolatum (pet.) (9.1%; P =.04103) in black men compared with white men (p-phenylenediamine [4.2%] and imidazolidinyl urea [2.6% pet.]).

CONCLUSION

The differences in sensitization rates, especially for p-phenylenediamine, may reflect variations in allergen exposure among racial groups or interindividual variations in the N-acetylation (N-acetyltransferase 1 [NAT1] and 2 [NAT2]) capacities of human skin for p-phenylenediamine.

A preliminary report of the occupation of patients evaluated in patch test clinics

BACKGROUND

The interplay between the occupational environment and worker's skin can result in contact dermatitis of both irritant and allergic types. Other forms of dermatitis can also be influenced by occupational exposures.

OBJECTIVE

The aim of this study is to compare the occupations and allergens of occupational contact dermatitis cases with nonoccupational contact dermatitis cases.

METHODS

Diagnostic patch testing with allergens of the North American Contact Dermatitis Group and occupational coding by the National Institute for Occupational Safety and Health methods.

RESULTS

Of 2,889 patients referred for evaluation of contact dermatitis, 839 patients (29%) were found to have occupational contact dermatitis. Of the 839 cases deemed occupational, 455 cases (54%) were primarily allergic in nature and 270 cases (32%) were primarily irritant in nature. The remaining 14% were diagnoses other than contact dermatitis, aggravated by work. The occupation most commonly found to have allergic contact dermatitis was nursing. Allergens strongly associated with occupational exposure were thiuram, carbamates, epoxy, and ethylenediamine.

CONCLUSION

Some contact allergens are more commonly associated with occupational contact dermatitis. Nursing and nursing support are occupations most likely to be overrepresented in contact dermatitis clinics.

Isolation and mass spectrometric characterization of dimeric adenine photoproducts in oligodeoxynucleotides

UVC irradiation of oligodeoxynucleotides (ODNs) at 254 nm generates two types of DNA photoproducts, A=A and (AA)*, at adjacent adenine sites in DNA. Kumar et al. previously proved the structure of these adducts in dinucleoside monophosphates [Kumar, S., et al. (1987) Nucleic Acids Res. 15, 1199-1216; Kumar, S., et al. (1991) Nucleic Acids Res. 19, 2841-2847]. Product-ion spectra of ESI-produced [M - 2H](2-) ions of the ODNs containing the dimeric adenine photoproducts show distinctive fragmentation that is informative of the structures of the photoproducts. The gas-phase cleavages of ODNs at sites of those photoproducts and thymine thymine or thymine adenine ((TA)*) photoproducts are analogous to cleavages induced by hot alkaline treatment. Nuclease-P1 digestions of ODNs containing dimeric adenine photoproducts give shorter pieces of ODNs bearing the photoproducts, which fragment under collisional activation conditions in a similar way to the large ODNs containing the photoproducts. The tandem mass spectrometric results show that the yield of (AA)* is lower than that of A=A when adjacent adenines are in the middle of an ODN sequence, and the yield of the latter is similar to that of (TA)*.

Fragmentation of electrospray-produced oligodeoxynucleotide ions adducted to metal ions

In this article, we describe the unique fragmentations of oligodeoxynucleotides (ODNs) whose phosphate groups are completely depleted of protons and replaced with metal ions. The production of the ubiquitous [a(n) - base] ions still occurs, but no longer by transfer of an acidic phosphate proton to an adjoining 3' base. Nor is the extent of the reaction determined by the proton affinity of that base. Rather, the reaction now occurs via a cleavage 3' to both pyrimidines and purines; cleavage 3' to pyrimidine is more favorable than that 3' to purine. We also demonstrate that an ODN is more stable in the gas phase when its phosphate groups are bound to metal ions than when its phosphate groups are attached to hydrogens. This study also provides further evidence for the ODN fragmentation mechanism that involves H transfer to a nucleobase. To establish the structural utility of this new fragmentation, we applied it to distinguishing small ODNs containing a photomodified cis,syn-cyclobutane pyrimidine dimer from the parent ODNs, a system that cannot be distinguished by collisional activation of precursor species that do not contain metal ions.

Prospective evaluation of the brain in asymptomatic children with neurofibromatosis type 1: relationship of macrocephaly to T1 relaxation changes and structural brain abnormalities

BACKGROUND AND PURPOSE

Mutation of the neurofibromatosis type 1 (NF-1) gene may be associated with abnormal growth control in the brain. Because macrocephaly could be a sign of abnormal brain development and because 30% to 50% of children with NF-1 display macrocephaly in the absence of hydrocephalus, we sought to determine the relationship between macrocephaly and other brain abnormalities in young subjects with NF-1. These subjects were free of brain tumor, epilepsy, or other obvious neurologic problems.

METHODS

We prospectively screened 18 neurologically asymptomatic subjects with NF-1, ages 6 to 16 years, using clinical measures, psychometric testing, conventional MR imaging, and quantitative MR imaging to measure T1.

RESULTS

Cranial circumference was 2 or more SDs above the age norm in seven (39%) of 18 subjects, a frequency of macrocephaly 17-fold higher than normal. Conventional MR imaging showed abnormalities in all 18 children, although there were more extensive abnormalities in subjects with macrocephaly. Macrocephaly in NF-1 was associated with enlargement of multiple brain structures, and brain T1 in macrocephalic subjects was reduced with respect to controls in the genu, frontal white matter, caudate, putamen, thalamus, and cortex. In normocephalic subjects, T1 was reduced only in the genu and splenium. Volumetric analysis showed that macrocephaly was associated specifically with enlargement of white matter volume.

CONCLUSION

Neurologically asymptomatic children with NF-1 showed macrocephaly, cognitive deficit, enlarged brain structures, and abnormally low brain T1. Macrocephaly in children with NF-1 may be associated with characteristic alterations in brain development, marked by more widespread and significant changes in T1, greater enlargement of midline structures, and greater volume of white matter.

Fellowship training and career outcomes for primary care physician-faculty

PURPOSE

To examine associations between fellowship training and career outcomes among primary care physician-faculty.

METHOD

A total of 821 full-time primary care physician-faculty from 24 representative U.S. medical schools were surveyed using a self-administered questionnaire. Primary outcomes were recent grant submissions and funding, career referred publications, rank, and salary. Findings were adjusted for demographic and professional characteristics.

RESULTS

Of the 500 respondents, 234 of the physician-faculty had completed a fellowship and 266 had not. Fellowship-trained physician-faculty were more than four times as likely to have submitted a grant proposal and to have had a grant funded (both p < 0.0001) than were physician-faculty without fellowship training. They were also more likely to have had any refereed publications (OR 3.8, p < 0.0001) and to have achieved senior academic rank (OR = 1.9, p = 0.02). Among those with fellowship experience, the amount of research training was important. Those with at least one year of research experience in their fellowship program had more grant proposal submissions (OR = 1.9, p = 0.02), more grants funded (OR = 2.9, p = 0.0003), more publications (OR = 2.4, p = 0.02), and higher academic ranks (OR 2.3, p = 0.03) than did those with less research training. Salaries were similar in every comparison.

CONCLUSION

Fellowship-trained primary care physician-faculty were more productive researchers and were more likely to have achieved senior academic rank than were their no-fellowship-trained peers. Even among physician-faculty with fellowship experience, more research training was associated with higher productivity and rank. Salaries were not affected by training experience.