An IgG complexed form of vitamin B12 is a common cause of elevated serum concentrations

ObjectivesTo report detailed investigations in a case of elevated serum B₁₂ due to the presence of an IgG–B₁₂ complex, to determine the prevalence of this phenomenon and to review the literature.Design and methods431 samples with elevated B₁₂ (median 1250 ng/L, range 901–114,480 ng/L) were treated with polyethylene glycol to precipitate immunoglobulin complexes. Samples with > 50% of precipitable B₁₂ (PPB₁₂) were further investigated by protein G adsorption, gel filtration chromatography and measurement of B₁₂ on different analytical platforms.ResultsMedian PPB₁₂ was 22.6%, but in 35 samples (8.1%), median PPB₁₂ was more than 50%. Investigation of 27 of these samples with protein G-Sepharose confirmed the presence of an IgG–B₁₂ complex in 24, and in 15 cases, B₁₂ fell to within the reference range. After treatment of serum with reagents releasing B₁₂ from binding proteins, immunoreactivity co-eluted with free B₁₂. Immunoreactivity of the IgG-bound form of B₁₂ was confirmed using five B₁₂ assays in common use in the UK.ConclusionsAt least 8% of samples with elevated vitamin B₁₂ contain an immunoglobulin complexed form of circulating B₁₂; this possibility should be considered in the interpretation of results.     

Radioactive isotope analyses of skeletal materials in forensic science: a review of uses and potential uses

A review of information that can be provided from measurements made on natural and anthropogenic radionuclide activities in human skeletal remains has been undertaken to establish what reliable information of forensic anthropological use can be obtained regarding years of birth and death (and hence post-mortem interval (PMI)). Of the anthropogenic radionuclides that have entered the environment, radiocarbon (¹⁴C) can currently be used to generate the most useful and reliable information. Measurements on single bones can indicate whether or not the person died during the nuclear era, while recent research suggests that measurements on trabecular bone may, depending on the chronological age of the remains, provide estimates of year of death and hence PMI. Additionally, ¹⁴C measurements made on different components of single teeth or on teeth formed at different times can provide estimates of year of birth to within 1–2 years of the true year. Of the other anthropogenic radionuclides, ⁹⁰Sr shows some promise but there are problems of (1) variations in activities between individuals, (2) relatively large analytical uncertainties and (3) diagenetic contamination. With respect to natural series radionuclides, it is concluded that there is no convincing evidence that ²¹⁰Pb dating can be used in a rigorous, quantitative fashion to establish a PMI. Similarly, for daughter/parent pairs such as ²¹⁰Po/²¹⁰Pb (from the ²³⁸U decay series) and ²²⁸Th/²²⁸Ra (from the ²³²Th decay series), the combination of analytical uncertainty and uncertainty in activity ratios at the point of death inevitably results in major uncertainty in any estimate of PMI. However, observation of the disequilibrium between these two daughter/parent pairs could potentially be used in a qualitative way to support other forensic evidence.     

Corticosteroid production by fetal rat hippocampal neurons

11beta-hydroxylase and aldosterone synthase catalyse the final stages of corticosterone and aldosterone synthesis respectively. Previously, we established that they are expressed in the rat brain, particularly the cerebellum and the hippocampus. Primary cultures of fetal rat neurons were studied. RT-PCR and immunohistochemistry established that neurons express 11beta-hydroxylase and aldosterone synthase mRNAs and protein. After incubating the cells with 10microM DOC for 24 hours, medium was analysed for aldosterone and corticosterone. Median % conversion of DOC to corticosterone was 7.6% compared to 0.4% in controls. Median % conversion of DOC to aldosterone was 6.2% compared to 0.06% in controls. Corticosteroids mediate a number of functions of mammalian brain, including blood pressure homeostasis, salt appetite and neuronal excitability. Local production of these steroids could have significant effects on these processes.     

Relationship between earmould venting, comfort and feedback

Although earmould venting is considered to make an earmould more comfortable, whether it does so remains to be proven in hearing-aid users. A hundred and six patients were sequentially fitted with a hearing aid in a randomized order with an unvented, a 0.8 mm vented or a 2 mm vented mould and questioned about various aspects of discomfort at the end of each trial period. The three moulds were equally uncomfortable (approximately 17% overall), moist (approximately 34% overall) and associated with an itchy sensation (approximately 36% overall). However, a 0.8 mm and a 2 mm vent significantly reduced the sensation of blockage from 35 to 22% (P less than 0.05) and 13% (P less than 0.001) respectively. A potential disadvantage of venting is feedback, but patients' reports of this can be confused with feedback due to incorrectly inserting the mould. A separate study showed that a 2 mm vent might cause feedback in approximately 10% of patients when used in conjunction with behind-the-ear aids whose maximum gain was 45 dB, but only when the gain was at 42 dB or greater.     

Staphylococcus aureus in the oral cavity: a three-year retrospective analysis of clinical laboratory data

OBJECTIVE: A retrospective analysis of laboratory data to investigate the isolation of Staphylococcus aureus from the oral cavity and facial area in specimens submitted to a regional diagnostic oral microbiology laboratory. METHODS: A hand search of laboratory records for a three-year period (1998-2000) was performed for specimens submitted to the regional diagnostic oral microbiology laboratory based at Glasgow Dental Hospital and School. Data were collected from forms where S. aureus was isolated. These data included demographics, referral source, specimen type, methicillin susceptibility and clinical details. RESULTS: For the period 1998-2000, there were 5,005 specimens submitted to the laboratory. S. aureus was isolated from 1,017 specimens, of which 967 (95%) were sensitive to methicillin (MSSA) and 50 (5%) were resistant to methicillin (MRSA). The 1,017 specimens were provided from 615 patients. MRSA was isolated from 37 (6%) of patients. There was an increasing incidence of S. aureus with age, particularly in the >70 years age group. The most common specimen from which MSSA was isolated was an oral rinse (38%) whilst for MRSA isolates this was a tongue swab (28%). The clinical condition most commonly reported for MSSA isolates was angular cheilitis (22%). Erythema, swelling, pain or burning of the oral mucosa was the clinical condition most commonly reported for MRSA isolates (16%). Patients from whom the MSSA isolates were recovered were most commonly (55%) seen in the oral medicine clinic at the dental hospital, whilst patients with MRSA were more commonly seen in primary care settings such as nursing homes, hospices and general dental practice (51%). CONCLUSION: In line with more recent surveys, this retrospective study suggests that S. aureus may be a more frequent isolate from the oral cavity than hitherto suspected. A small proportion of the S. aureus isolates were MRSA. There were insufficient data available to determine whether the S. aureus isolates were colonising or infecting the oral cavity. However, the role of S. aureus in several diseases of the oral mucosa merits further investigation.     

Factors influencing the decision to amputate or reconstruct after high-energy lower extremity trauma

BACKGROUND: Factors thought to influence the decision for limb salvage include injury severity, physiologic reserve of the patient, and characteristics of the patient and their support system. METHODS: Eligible patients were between the ages of 16 and 69 with Gustilo type IIIB and IIIC tibial fractures, dysvascular limbs resulting from trauma, type IIIB ankle fractures, or severe open midfoot or hindfoot injuries. Data collected at enrollment relevant to the decision-making process included injury characteristics and its treatment, and the nature and severity of other injuries. Logistic regression and stepwise modeling were used to determine the effect of each covariate on the variable salvage/ amputation. RESULTS: Of 527 patients included in the analysis, 408 left the hospital with a salvaged limb. Of the 119 amputations performed, 55 were immediate and 64 were delayed. The multivariate analysis confirmed the bivariate analysis: all injury characteristics remained significant predictors of limb status with the exception of bone loss; and soft tissue injury and absence of plantar sensation were the most important factors in accounting for model validity. CONCLUSION: Soft tissue injury severity has the greatest impact on decision making regarding limb salvage versus amputation.