Uptake of selenium and mercury by captive mink: Results of a controlled feeding experiment.

Captive, juvenile, ranch-bred, male mink (Neovison vison) were fed diets containing various concentrations of methyl-mercury (MeHg) and selenium (Se) for a period of 13 weeks and then sacrificed to determine total Hg levels in fur, blood, brain, liver and kidneys and total Se concentrations in brain tissue. As MeHg concentrations in the diet increased, concentrations of total Hg in the tissues also increased with the highest level occurring in the fur > liver = kidney > brain > blood. Concentrations of Hg in the fur were correlated (r(2) > 0.97) with liver, kidney, blood and brain concentrations. The addition of Se to the mink diet did not appear to affect most tissue concentrations of total Hg nor did it affect the partitioning of Hg between the liver:blood, kidney:blood and brain:blood; however, partitioning of Hg between fur and blood was apparently affected.

Seasonal variation in mortality of Pneumocystis jirovecii pneumonia in HIV-infected patients.

A seasonal variation in the presentation of Pneumocystis jirovecii pneumonia (PCP) has been reported and a previous study from this centre noted a seasonal variation in mortality rates. This study examined seasonal influences (including climatic factors) within-host factors (clinical and laboratory-derived variables), the infectious burden of P. jirovecii in bronchoalveolar lavage (BAL) fluid, the presence of dihydropteroate synthase (DHPS) mutations in P. jirovecii, variations in knowledge and skills of junior medical staff, and mortality in 547 episodes of PCP occurring in 494 HIV-infected patients. The overall mortality rate was 13.5%. There was a seasonal variation in mortality: highest in autumn (21.2%) and lowest in spring (9.7%), P = 0.047. After adjustment was made for prognostic factors previously identified as being associated with mortality (increasing patient age, second/third episode of PCP, low haemoglobin, low PaO(2), presence of medical co-morbidity and pulmonary Kaposi sarcoma), there was no seasonal association with mortality, P = 0.249. The quantity of P. jirovecii DNA in BAL fluid showed no evidence of seasonal variation, P = 0.67; DHPS mutations were identified with equal frequency in each season and the mortality rate for February and August (when junior medical staff arrive in new posts) was 16.7%, only slightly greater than for other months (13.0%).

Prognostic value of C-reactive protein in HIV-infected patients with Pneumocystis jirovecii pneumonia.

C-reactive protein (CRP) is a sensitive marker of inflammation and tissue damage. We aimed to describe CRP responses in HIV-infected patients presenting with Pneumocystis pneumonia (PCP), bacterial pneumonia (BP) and pulmonary tuberculosis (TB) and, in patients with PCP, to identify if elevated CRP has prognostic significance. Data obtained by case-note review of consecutive HIV-infected adults with acute respiratory episodes included admission CRP (elevated >5 mg/L), haemoglobin, white blood count, CD4 count and partial pressure of oxygen in the blood (PaO(2)), presence of pulmonary co-pathology/intercurrent infection and outcome (survival). Median (range) CRP in patients with BP = 120 mg/L (<5-620 mg/L), TB = 44 mg/L (<5-256.3 mg/L) and PCP = 35 mg/L (<5-254 mg/L). CRP was elevated in 93/103 (90.3%) patients with PCP; six patients died; and all had an elevated CRP. PaO(2) and CRP values were associated as follows: average CRP levels declined by 10% (95% confidence interval [CI] 0.20%) per kPa increase in PaO(2) = 0.002. Factors associated with death were higher CRP, odds ratio (OR) (95% CI) = 5.30 (1.61 to 17.51) per 100 mg/L increase, P = 0.006 and haemoglobin, OR (95% CI) = 0.52 (0.29 to 0.93) per g/dL, P = 0.033. CRP is elevated in the majority of HIV-infected patients with PCP, BP and TB. Admission CRP measurement lacks specificity, but in PCP elevations of CRP are associated with disease severity (PaO(2)) and poor outcome and might be used prognostically, together with other mortality risk factors; further prospective evaluation is needed.

Primary care consultations and costs among HIV-positive individuals in UK primary care 1995-2005: a cohort study.

OBJECTIVES: To investigate the role of primary care in the management of HIV and estimate primary care-associated costs at a time of rising prevalence. METHODS: Retrospective cohort study between 1995 and 2005, using data from general practices contributing data to the UK General Practice Research Database. Patterns of consultation and morbidity and associated consultation costs were analysed among all practice-registered patients for whom HIV-positive status was recorded in the general practice record. RESULTS: 348 practices yielded 5504 person-years (py) of follow-up for known HIV-positive patients, who consult in general practice frequently (4.2 consultations/py by men, 5.2 consultations/py by women, in 2005) for a range of conditions. Consultation rates declined in the late 1990s from 5.0 and 7.3 consultations/py in 1995 in men and women, respectively, converging to rates similar to the wider population. Costs of consultation (general practitioner and nurse, combined) reflect these changes, at pound100.27 for male patients and pound117.08 for female patients in 2005. Approximately one in six medications prescribed in primary care for HIV-positive individuals has the potential for major interaction with antiretroviral medications. CONCLUSION: HIV-positive individuals known in general practice now consult on a similar scale to the wider population. Further research should be undertaken to explore how primary care can best contribute to improving the health outcomes of this group with chronic illness. Their substantial use of primary care suggests there may be potential to develop effective integrated care pathways.

Trends in HIV testing and recording of HIV status in the UK primary care setting: a retrospective cohort study 1995-2005.

OBJECTIVES: To provide nationally representative data on trends in HIV testing in primary care and to estimate the proportion of diagnosed HIV positive individuals known to general practitioners (GPs). METHODS: We undertook a retrospective cohort study between 1995 and 2005 of all general practices contributing data to the UK General Practice Research Database (GPRD), and data on persons accessing HIV care (Survey of Prevalent HIV Infections Diagnosed). We identified all practice-registered patients where an HIV test or HIV positive status is recorded in their general practice records. HIV testing in primary care and prevalence of recorded HIV positive status in primary care were estimated. RESULTS: Despite 11-fold increases in male testing and 19-fold increases in non-pregnant female testing between 1995 and 2005, HIV testing rates remained low in 2005 at 71.3 and 61.2 tests per 100,000 person years for males and females, respectively, peaking at 162.5 and 173.8 per 100,000 person years at 25-34 years of age. Inclusion of antenatal tests yielded a 129-fold increase in women over the 10-year period. In 2005, 50.7% of HIV positive individuals had their diagnosis recorded with a lower proportion in London (41.8%) than outside the capital (60.1%). CONCLUSION: HIV testing rates in primary care remain low. Normalisation of HIV testing and recording in primary care in antenatal testing has not been accompanied by a step change in wider HIV testing practice. Recording of HIV positive status by GPs remains low and GPs may be unaware of HIV-related morbidity or potential drug interactions.

Development and evaluation of a real-time PCR assay for detection of Pneumocystis jirovecii DNA in bronchoalveolar lavage fluid of HIV-infected patients.

BACKGROUND: Pneumocystis pneumonia (PCP) is conventionally diagnosed by identifying Pneumocystis jirovecii in lower respiratory tract samples using cytochemical stains. Molecular diagnosis of PCP is potentially more sensitive. METHODS: A study was undertaken to use an extensively optimised real-time polymerase chain reaction (PCR) using primers designed to hybridise with the P. jirovecii heat shock protein 70 (HSP70) gene to quantify P. jirovecii DNA in bronchoalveolar lavage (BAL) fluid from HIV-infected patients with and without PCP, and to compare this assay with conventional PCR targeting the P. jirovecii mitochondrial large subunit rRNA gene sequence (mt LSU rRNA). RESULTS: Sixty-one patients had 62 episodes of PCP (defined by detection of P. jirovecii in BAL fluid by cytochemical stains and typical clinical presentation). Quantifiable HSP70 DNA was detected in 61/62 (range approximately 13-18,608 copies/reaction; median approximately 332) and was detectable but below the limit of quantification (approximately 5 copies/reaction) in 1/62. Seventy-one other patients had 74 episodes with alternative diagnoses. Quantifiable HSP70 DNA was detectable in 6/74 (8%) episodes (range approximately 6-590 copies/reaction; median approximately 14) and detectable but below the limit of quantification in 34/74 (46%). Receiver-operator curve analysis (cut-off >10 copies/reaction) showed a clinical sensitivity of 98% (95% 91% to 100%) and specificity of 96% (95% CI 87% to 99%) for diagnosis of PCP. By contrast, clinical sensitivity of mt LSU rRNA PCR was 97% (95% CI 89% to 99%) and specificity was 68% (95% CI 56% to 78%). CONCLUSION: The HSP70 real-time PCR assay detects P. jirovecii DNA in BAL fluid and may have a diagnostic application. Quantification of P. jirovecii DNA by real-time PCR may also discriminate between colonisation with P. jirovecii and infection.

Climate and genotypes of Pneumocystis jirovecii.

This study explored whether seasonal and/or climatic factors influenced detection of specific genotypes of Pneumocystis jirovecii. Between 1989 and 2001, 155 isolates of P. jirovecii were obtained from patients undergoing bronchoscopic alveolar lavage. For each isolate, the month and climatic conditions were noted. Genotypes of P. jirovecii were distinguished by polymorphisms in the mitochondrial large-subunit rRNA gene. There were monthly and seasonal variations in the frequency of detection of mixed genotypes (p 0.018 and p 0.031, respectively) and genotype 2 (p 0.029 and p 0.086, respectively). There was no association between month/season and genotypes 1, 3 and 4, or between monthly temperature or rainfall and any genotype.

Uptake and elimination of lead, zinc, and copper by caddisfly larvae (Trichoptera: Hydropsychidae) using stable isotope tracers.

Stable isotopes of Pb, Zn, and Cu were used in laboratory experiments to determine the uptake and elimination of these metals by stream-dwelling caddisfly (Trichoptera: Hydropsychidae) larvae. For Pb and Cu, larvae were exposed to environmentally realistic levels (2.5 and 4.5 microg x L(-1), respectively) of one isotope for 9 days followed by a 9-day exposure to either the same isotope, to a second stable isotope of the same metal, or to RW containing no added isotope (two phases in total). For zinc, the exposure concentration was 15 microg x L(-1), and the experiment lasted for a total of 27 (i.e., three phases) rather than 18 days to see if uptake and elimination changed during the extended time period. The uptake clearances (k(u)) determined for the various metals averaged 7.8, 1.4, and 0.6 L x g dw(-1) x d(-1) for Pb, Zn, and Cu, respectively, if the total metal concentration in the water was used in the calculations. The clearance rate constants (k(e)) were less variable, averaging 0.15 d(-1) for Pb, 0.22 d(-1) for Zn, and approximately 0.1 d(-1) for Cu and were similar in both the presence (i.e., elimination) and absence (i.e., depuration) of metal in the water. These values are also comparable with those reported in the literature for other aquatic invertebrates. The use of stable isotopes thus allowed simultaneous measurement of uptake and clearance (elimination and depuration) of these metals at environmentally realistic concentrations and could be of great benefit for determining partitioning, assimilation efficiency, and pathways of these and other metals in the environment.

Attenuation of the virulence of Porphyromonas gingivalis by using a specific synthetic Kgp protease inhibitor.

The Arg- and Lys-gingipains of Porphyromonas gingivalis are important virulence determinants in periodontal disease and may correspond to targets for immune- or drug-based treatment strategies. In this investigation we aimed to determine which of these enzymes represents the most promising molecular target for protease inhibitor-based therapy and to examine the effectiveness of the resultant compound in a murine virulence assay. Isogenic mutants with mutations in rgpA and rgpB (encoding Arg-gingipains) and in kgp (encoding Lys-gingipain) and a double mutant with mutations in rgpA and rgpB were prepared by using P. gingivalis W50. The virulence of these mutants indicated that Kgp is a promising drug target. Combinatorial chemistry was used to define the optimal substrate of Kgp, and from this information a specific slowly reversible inhibitor with a nanomolar K(i) was designed and synthesized. Growth of P. gingivalis W50 in the presence of this compound resembled the phenotype of the kgp isogenic mutant; in both instances bacterial colonies failed to form pigment on blood agar, and only poor growth was obtained in a defined medium containing albumin as the sole protein source. Furthermore, pretreatment of the wild-type organism with the Kgp inhibitor led to a significant reduction in virulence in the murine assay. These data emphasize the conclusion that Kgp is an important factor for both nutrition and virulence of P. gingivalis and that inhibitors of this enzyme may have therapeutic potential for the control of P. gingivalis infections. Protease inhibitors may be a potentially novel class of antimicrobial agents with relevance to the control of other bacterial pathogens.

Comparison of iron accumulation in lakes using sediment core and mass balance calculations.

The accumulation of iron (Fe) in several lakes in Ontario, Canada was determined by two independent approaches. First, Fe accumulation was calculated in cores collected from several sites in each lake by integrating Fe concentration profiles with sediment accumulation rates determined from Pb210 dating. These site-specific accumulation rates were corrected for sediment focussing so that whole-lake Fe accumulation values could be derived. Using this approach, recent whole-lake Fe accumulation in eight lakes ranged between approximately 750 and 4000 mg/m2 per year. Second, whole-lake Fe accumulation was estimated from lake mass budgets, which were measured over a maximum of 14 years. Accumulation measured using the mass balances ranged from 10 to 1330 mg/m2 per year. Comparison of the two approaches indicated that retentions calculated from the sediment cores were much greater than those estimated from the mass balances. The most likely explanation for this difference is that, in the two decades since the cores were collected, there has been a substantial decline in Fe retention (in mass units but not percent) in the study lakes, principally as a result of reduced inputs of Fe from the catchments.

Implications for space radiation environment models from CREAM & CREDO measurements over half a solar cycle.

Flight data obtained between 1990 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSAT-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) provide coverage over half a solar cycle. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor of three increase at high latitudes and the latter a general increase accompanied by a north-westward drift. Comparison of particle fluxes and linear energy transfer (LET) spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatment of locally produced secondary particles. Solar-particle events during this time period have LET spectra significantly below the October 1989 event which has been proposed as a worst case model.

Updated measurements from CREAM & CREDO & implications for environment & shielding models.

Flight data obtained between 1995 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSat-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) have been added to the dataset affording coverage since 1990. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor three increase at high latitudes and the latter a general increase accompanied by a westward drift. Comparison of particle fluxes and linear energy transfer spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatrnent of locally produced secondary particles.

Observations and predictions of secondary neutrons on Space Shuttle and aircraft.

The Cosmic Radiation Effects and Activation Monitor has flown on six Shuttle flights between September 1991 and February 1995 covering the full range of inclinations as well as altitudes between 220 and 570 km, while a version has flown at supersonic altitudes on Concorde between 1988 and 1992 and at subsonic altitudes on a SAS Boeing 767 between May and August 1993. The Shuttle flights have included passive packages in addition to the active cosmic ray monitor which comprises an array of pin diodes. These are positioned at a number of locations to investigate the influence of shielding and local materials. Use of both metal activation foils and scintillator crystals enables neutron fluences to be inferred from the induced radioactivity which is observed on return to Earth. Supporting radiation transport calculations are performed to predict secondary neutron spectra and the energy deposition due to nuclear reactions in silicon pin diodes and the induced radioactivity in the various scintillator crystals. The wide variety of orbital and atmospheric locations enables investigation of the influence of shielding on cosmic ray, trapped proton and solar flare proton spectra.

Congenital syphilis.

Congenital syphilis offers many parallels with perinatal HIV infection. Both affect multiple organs including the central nervous system, may be asymptomatic for months to years, and pose diagnostic dilemmas, especially from a laboratory perspective. Syphilis is a co-infection in some cases of HIV. Public policy issues raised by the AIDS epidemic, including stigmatization, discrimination, and denial of access to health care, have their antecedents in syphilis.

Public policy and AIDS.

In summary of some of the major issues raised by AIDS (Table 1), social, political, and economic forces all impact on the global outbreak of AIDS. Conversely the epidemiologic and medical realities of this disease have forced a reconsideration of moral and ethical values, prioritization of resource allocation, and pervasion of virtually every aspect of the health care delivery system. Advocates for AIDS funding have set a model for other espousing the significance of diseases ranging from rare disorders to breast cancer. As this issue was written (summer 1993), it was apparent that attention of the media had shifted to numerous other domestic and foreign concerns. Hopefully, when the Clinics next present perinatal AIDS, the pendulum will have swung back and there will be a wider variety of effective therapeutic agents available permitting longer survival of greater quality.

The effect of 60% oxygen on air-space enlargement and cross-linked elastin synthesis in hamsters with elastase-induced emphysema.

Hyperoxia is routinely administered to patients with severe emphysema. To gain insight into the possibly adverse effects of such treatment, hamsters were exposed to 60% oxygen for 5 days, beginning 48 h after induction of pulmonary emphysema by intratracheal instillment of pancreatic elastase. Control groups consisted of (1) animals instilled with elastase and exposed to room air, (2) animals instilled with saline and exposed to 60% oxygen, and (3) animals instilled with saline and exposed to room air. Cross-linked elastin content and synthesis in the lung were measured immediately following termination of hyperoxia, and the mean linear intercept was determined 4 wk later. Cytologic examination of bronchoalveolar lavage fluids was also performed. Statistical significance was determined by a two-way analysis of variance. Results indicate that exposure to 60% oxygen significantly affected (p less than 0.05) air-space size, causing a 51% increase among elastase-treated hamsters (124 versus 82 microns) but only a 4% increment among saline-treated animals (52 versus 50 microns). When compared to other groups, animals treated with both elastase and hyperoxia had a significantly greater (p less than 0.01) percentage of neutrophils (28%) in their lung lavage fluids immediately following exposure to 60% oxygen. Although total lung elastin content was not altered by hyperoxia at this time, labelling of elastin cross-links was significantly increased (p less than 0.05). These studies demonstrate that exposure to 60% oxygen enhances elastase-induced lung injury. They also raise the possibility that oxygen therapy may, under certain circumstances, accelerate the progression of human emphysema.

Improvement of neutrophil migration by systemic vitamin C in neonates.

The effect of oral vitamin C on chemotactic and random migration of neutrophils in 20 neonates (10 normal and 10 with suspected sepsis) was evaluated. Chemotaxis and random migration were studied between 24 and 48 hours of life, before and 24 hours after the administration of 400 mg (divided in four doses) of vitamin C. Chemotactic migration improved by 65% and random migration by 57% following vitamin C administration. The significant improvement in chemotaxis (P less than .01) and random migration may justify the inclusion of vitamin C as an adjunct to the therapy of neonatal sepsis.

Morphology and embryological interpretation of a congenital occipito-atlanto-axial malformation in a dog.

A clinical, radiological, and morphological study of a congenital occipito-atlanto-axial malformation in a 13-week-old male Saint Bernard dog that became suddenly tetraplegic at 8 weeks is described. The dog was recumbent, had generalized muscle atrophy, but was alert and responsive. Pain was elicited when the head-neck junction and the cervical vertebrae were palpated, and a bony abnormality was palpated at the occiput and atlas. Clinical signs of upper motor neuron and general proprioceptive deficits in all four limbs were compatible with a focal lesion in the cervical spinal cord. Plain radiographs of the head and neck revealed malformation of the occipital bones, atlas, and axis, unilateral atlanto-occipital fusion, and atlanto-axial subluxation. At necropsy the right half of the atlantal neural arch was fused to the right exoccipital bone. On the axis, the dens was small, malformed, and deviated to the left; the transverse processes were enlarged; and the spinous process was small with a cleft caudally. The spinal cord was severely compressed at the level of the atlanto-axial articulation, and histological examination revealed extensive loss of neuronal cell bodies, axons, myelin, and the central canal. Reactive astrogliosis was also extensive. After a discussion of normal and abnormal development of the vertebral column and its joints, it was concluded that a failure of normal joint development at about 30 days of gestation in the dog could lead to congenital occipito-atlanto-axial malformation.