Nuclear imaging modalities for cardiac amyloidosis

Amyloidosis is a heterogeneous group of diseases characterized by localized or systemic deposition of insoluble extracellular fibrillary proteins in organs and tissues. Several types of amyloid can infiltrate the heart resulting in a restrictive cardiomyopathy, heart failure, and atrial and ventricular arrhythmias. Scintigraphy is a noninvasive method that may facilitate early diagnosis, distinguish various forms of cardiac amyloid, and may be useful in following disease burden. The amyloid-specific tracers presented in this article have been used with planar imaging and/or single-photon emission computed tomography. To date, there are no approved cardiac amyloid tracers although investigational tracers are currently under examination. This article serves to review the current nuclear imaging modalities available in the detection of cardiac amyloid.     

Underweight and overweight men have greater exercise-induced dyspnoea than normal weight men

Introduction.

Persons with high or low body mass index (BMI), involved in clinical or mechanistic trials involving exercise testing, might estimate dyspnoea differently from persons with a normal BMI.

Aims.

Our objective was to investigate the relationship between BMI and dyspnoea during exercise in normal subjects with varying BMI.

Material and methods.

A total of 37 subjects undertook progressive exercise testing. Subjects were divided into three groups: underweight (UW), normal weight (NW), and overweight (OW). Dyspnoea was estimated using the visual analogue scale (VAS). Spirometry, maximum voluntary ventilation (MVV), and respiratory muscle strength (RMS) were measured.

Results and discussion.

The intercept of the VAS/ventilation relationship was significantly higher in NW subjects compared to UW (P = 0.029) and OW subjects (P = 0.040). Relative to the OW group, FVC (P = 0.020), FEV₁ (P = 0.024), MVV (P = 0.019), and RMS (P = 0.003) were significantly decreased in the UW group. The greater levels of dyspnoea in UW subjects could possibly be due to decreased RMS. Healthy persons should aim to achieve an optimum BMI range to have the lowest exercise-induced dyspnoea.     

Acute effects of MK63 stun device discharges in miniature swine

OBJECTIVE: Electromuscular incapacitation (EMI) devices are being used and evaluated by both military and law enforcement agencies. Although the gross muscular response is obvious, physiological responses to these devices are poorly understood. We hypothesized that the intense, repetitive, muscle contractions evoked by EMI devices would cause dose-dependent metabolic acidosis, accompanied by neuromuscular or cardiac injury. METHODS: Using an approved protocol, 26 Yucatan mini-pigs (22 experimental animals and 4 control animals) were anesthetized with ketamine and xylazine. Experimental animals were exposed to MK63 (Aegis Industries, Bellevue, Idaho) discharges over the left anterior hind limb for 10, 20, 40, or 80 seconds. Electrocardiograms, electromyograms, troponin I levels, blood gas values, and electrolyte levels were recorded before and 5, 15, 30, and 60 minutes and 24, 48, and 72 hours after discharge. Skin, muscle, and nerve biopsies were taken from the shocked and contralateral sides. RESULTS: Core body temperature significantly decreased (1.0-1.5 degrees C) in all shocked animals but not in sham-treated control animals. No cardiac dysrhythmias or deaths were seen, and heart rate was unaffected. No clinically significant changes were seen in troponin I, myoglobin, or creatine kinase-MB levels. Central venous blood pH decreased, whereas carbon dioxide pressure and lactate levels increased for 60 minutes after discharge. All values returned to normal by 24 hours after discharge, and no significant histological or electromyographic changes were found. CONCLUSIONS: Changes in blood chemistry were observed but were of little clinical significance, and no neuromuscular damage was detected. Therefore, within the limitations of this model, it appears that EMI can safely be achieved by using this device, even for lengthy periods, without causing significant injury.     

A rare combination of carotid artery congenital abnormalities: understanding the embryology and clinical associations

Duplication of an extracranial internal carotid artery, a retropharyngeal carotid transposition, an aberrant internal carotid artery in the middle ear, and a persistent stapedial artery are each individually uncommon vascular variants. In this case report, we discuss a rare occurrence of all four of these variants in a single individual who presented to our emergency department with a complaint of dizziness and a recent fall. Included in the discussion is pertinent embryology and clinical associations.     

Evaluation of Erythropoiesis by Serum Transferrin Receptor and Ferritin in Infants Aged 0–6 Months

The aim of this study was to evaluate erythropoiesis in 198 healthy babies aged 0–6 months by determination of their blood count, serum transferrin receptor (STfR), and ferritin levels. Anemia and microcytosis were present in 9% and 13% of the sample, respectively. Microcytosis rate was as high as 45% in 6-month-old babies. In infants with normal blood counts, the values of sTfR/ferritin and sTfR-F index were increasing with the increase of sTfR and decrease of ferritin beginning from 2 months of age. In the 5- to 6-month-old group, sTfR concentrations, sTfR/ferritin ratio, and sTfR-F index were higher in infants with anemia and microcytosis. This research showed a high frequency of iron deficiency detected in otherwise healthy babies. Only problems with early weaning practices were found to be significantly more common in babies with iron deficiency.     

Time course of appearance and disappearance of human mast cell tryptase in the circulation after anaphylaxis.

Tryptase, a neutral protease of human mast cells, is a potentially important indicator of mast cell involvement in various clinical conditions. The current study examined the time course of appearance and disappearance of tryptase in the circulation after an anaphylactic event and the stability of both endogenous and exogenous tryptase in terms of freeze-thawing and temperature. The peak level of tryptase after an experimentally induced systemic anaphylactic reaction occurred 1-2 h after the initiating bee sting in each of three subjects, in contrast to histamine levels which peaked at 5-10 min. In some cases elevated levels of tryptase may not be detected during the initial 15-30 min. Tryptase levels then declined under apparent first order kinetics with a t1/2 of approximately 2h. Similar disappearance kinetics were observed for two subjects presenting in the emergency room with immediate type reactions, one with severe asthma after indomethacin ingestion, the other with systemic anaphylaxis after a bee sting. Histamine levels declined rapidly and were back to baseline by 15-60 min. Measured levels of tryptase in serum or plasma were not diminished by up to four freeze-thaw cycles. Incubation of serum samples taken from subjects with elevated levels of tryptase at 22 and 37 degrees C indicated that greater than 50% of endogenous tryptase was still detected after 4 d. Purified tryptase added to serum or plasma and incubated as above was less stable: approximately 50% of exogenous tryptase in serum and approximately 15% in plasma was detected after 2d of incubation. Therefore, optimally samples should be stored frozen, but even those stored at room temperature for up to 4 d should be satisfactory. The best time to obtain samples for tryptase determinations is 1-2 h after the precipitating event, but depending on the magnitude of the initial response elevated levels of tryptase may be present in the circulation for several hours.     

An association study of five genetic loci and left ventricular hypertrophy amongst Gulf Arabs.

We carried out an association (case-control) study of five candidate genes--G-protein beta3 subunit gene variant; methylene tetrahydrofolate reductase (MTHFR); angiotensin converting enzyme (ACE) gene; and paraoxonase 1 and 2 (PON 1 and 2) genes--in a United Arab Emirati population. The aim was to establish a possible relationship between these five candidate genes and clinical left ventricular hypertrophy (LVH) in a genetically homogenous group. DNA samples were collected from 213 unrelated Nationals who were further segregated into 98 subjects with LVH (78 hypertensives and 20 normotensives) and 115 (23 hypertensives and 92 normotensives) age- and sex-matched controls who did not present with LVH. Of the five candidate gene markers studied, no significant differences in the genotype distribution of the MTHFR, PON 1 and 2 or ACE markers were found between the LVH and non-LVH groups. However, a possible association was found between the beta3 G-protein C825T marker and LVH. In conclusion, our results suggest an association between LVH and the C825T allele of the G-protein beta3 subunit gene.     

Severe burn injury: Body Mass Index and the Baux score

Objective: The revised Baux score (age total body surface area (TBSA) burned and inhalation injury)) is predictive of mortality in burn patients. Our study objective was to assess whether the addition of body mass index (BMI) to the revised Baux score would be of value. We posited that increasing BMI follows a pattern similar to age and TBSA in the revised Baux score after severe burn injury. Methods: Patient data from the burn registry was queried for patients admitted between 1/1/2013 to 8/31/2019. Patients 12 years or older with a TBSA of 20% or greater burn were included. Inpatient outcomes were analyzed based on BMI. Results: 56 of 1365 patients met inclusion criteria. Mean age of the study population was 48.25 years and 64.3% of patients were male. Median BMI was 25.8 and median TBSA was 26.5. Inhalation injury was present in 44.6% (25/56) of patients. Median hospital length of stay (LOS) and ICU LOS were 21.5 and 17 days respectively. On bivariate analysis, non-survivors had higher TBSA (41.5% vs 25.5%, p = 0.034), more inhalation injury (83.3%, 10/12 vs 34.8%, 15/43 p = 0.003) and higher complication rates (91.6%, 11/12 vs 59.1 %, 25/43, p = 0.043). Survivors also had higher BMI (28.2 vs 23, p = 0.003) and increased hospital LOS (24 vs 5.5, p = 0.003). Automatic model fit in binary logistic regression showed a negative relationship between BMI and mortality. Conclusion: We found a negative relationship between BMI and mortality. Pre-obesity appears to have a protective role, but BMI was not found to be a useful addition to the revised Baux score. Larger sample sizes may be of benefit a for a for a more definitive understanding of the role of BMI with regards to burn survival.