Hernan F. Gomez

Severe gamma-hydroxybutyrate withdrawal: a case report and literature review

We report a case of gamma-hydroxybutyrate (GHB) withdrawal resulting in severe agitation, mental status changes, elevated blood pressure, and tachycardia hours after stopping chronic use of GHB. The patient admitted to substantial GHB abuse on a daily basis for 2.5 years. Previous attempts at cessation reportedly resulted in diaphoresis, tremors, and agitation. The patients symptoms, negative polypharmacy history, and negative urine and blood toxicological analysis for alcohol, benzodiazepines, sedative-hypnotics, or other substances suggested the diagnosis of GHB withdrawal. Later analysis of a patient drug sample confirmed the presence of GHB. The patient required 507 mg of lorazepam and 120 mg of diazepam over 90 h to control agitation. This is one of the few reported cases of GHB withdrawal and one of the most severe. Given the increasing use of GHB, more cases of severe GHB withdrawal should be anticipated.

Loxosceles Spider Venom Induces the Production of α and β Chemokines: Implications for the Pathogenesis of Dermonecrotic Arachnidism

Bites from the brown recluse spider and other Loxosceles arachnids result in dermonecrotic skin lesions. Neutrophils (PMN) are essential to the development of Loxosceles-induced skin lesions, but paradoxically, in vitro PMN activation is inhibited by direct exposure to Loxosceles venom. Neutrophil activation occurs in response to a myriad of soluble mediators that include members of both the α and β chemokine families. Because arachnid envenomation results in the exposure of several different cell types to venom, we investigated venom-induced expression of α and β chemokines in both endothelial cells (human umbilical vein; HUVEC) and epithelial cells (A549 pneumocytes). Chemokine-specific capture enzyme immunoassays (EIA) were used to measure Loxosceles deserta venom-induced α chemokines: interleukin-8 (IL-8), growth-related oncogene-alpha (GRO-α), and β chemokines: monocyte chemoattractant protein-1 (MCP-1), and regulated on activation, normal T cell expressed and secreted (RANTES) in cell-free conditioned media from HUVEC and A549 cell monolayers. Exposure of HUVECs (8 h) to Loxosceles venom resulted in the production of IL-8 (5.2 ± 1.30 ng/ml), MCP-1 (1.44 ± 0.11 ng/ml) and GRO-α (1.97 ± 0.15 ng/ml) in a dose and time-dependent manner. Exposure of A549 cell monolayers to venom resulted in IL-8 (7.74 ± 0.30 ng/ml), and MCP-1 (2.61 ± 0.31 ng/ml), but neither GRO-α nor RANTES accumulated during an 8-hour incubation period. Chemokines accumulated in a venom dose and time-dependent manner. Neither cell type secreted RANTES in response to Loxosceles venom. These data indicate that Loxosceles spider venom is a potent inducer of α and β chemokines in both endothelial and epithelial cell types. Based on the established roles of IL-8, MCP-1, and GRO-α, in inflammation, these observations have relevance to the pathophysiology of Loxosceles-Induced dermonecrosis.

Mediators of microvascular injury in dermal burn wounds

In previous studies we have demonstrated that second-degree thermal injury of skin in rats leads to secondary effects, such as systemic complement activation, C5a-mediated activation of blood neutrophils, their adhesion-molecule-guided accumulation in lung capillaries and the development of acute pulmonary injury, largely caused by neutrophil-derived toxic oxygen metabolites. In the dermal burn wound, however, pathophysiologic events are less well understood. The injury is fully developed at four hours post-burn. To further elucidate the pathogenesis of the “late phase” dermal vascular damage, rats were depleted of neutrophils or complement by pretreatment with rabbit antibody against rat neutrophils or with cobra venom factor, respectively. In other experiments, rats were treated with blocking antibodies to IL-6, IL-1, and TNFα immediately following thermal burning or were pretreated with hydroxyl radical scavengers (dimethyl sulfoxide, dimethyl thiourea). Extravasation of 125I-labeled bovine serum albumin into the burned skin was studied, as well as, skin myeloperoxidase levels. The studies revealed that, like in secondary lung injury, neutrophils and toxic oxygen metabolites, are required for full development of microvascular injury. In contrast, however, development of dermal vascular damage in thermally injured rats was not affected by complement depletion. Our data suggest that the development of microvascular injury in the dermal burn wound is complement-independent, involves the pro-inflammatory cytokines IL-1, TNFα and IL-6, and may result from reactive oxygen metabolites generated by neutrophils accumulating in the burn wound.

Antigenic cross-reactivity of venoms from medically important North American Loxosceles spider species

We characterized the antigenic cross-reactivity of two medically important North American Loxoxceles species: L. reclusa (native to southeastern US) and L. deserta (native to southwestern US). Dermonecrosis resulting from bites from these two North American spider species are indistinguishable clinically. Polyclonal IgG antivenins directed against L. reclusa and L. deserta were raised in rabbits and used to develop specific enzyme immunoassays (EIAs). Antigenic differences in the two venoms were evaluated as follows: (1) Comparison of the sensitivities and correlation coefficient (R(2)) of anti-L. reclusa (alpha LoxR) and anti-L. deserta antibodies (alpha LoxD) in the detection of varying concentrations of the two venoms; (2) separation and western blot comparison of venom components; (3) protein sequence analysis of L. desertavenom and comparison to the L. reclusa protein sequence analysis present in a US national database; and (4) in vivo evaluation of alpha LoxR and alpha LoxD antivenins in attenuating dermal lesions (rabbit model). Correlation coefficients for alpha LoxR (R(2)=0.99) and alpha LoxD (R(2)=0.99) polyclonal antibodies in the measurements of standard concentrations of venoms were virtually identical. Western blot analysis revealed multiple common bands between the two venoms. Amino acid data (amino acids 1-35, N-terminal) of the active venom components of the two venoms revealed only three non-identical amino acids. alpha LoxR and alpha LoxD antivenins were similarly effective in blocking the development of rabbit skin lesions (ANOVA p<0.05). In summary, L. reclusa and L deserta spider venoms possess several common protein bands as identified by western blot, greater than 90% amino acid sequence identity, and marked antigenic cross-reactivity.

Loxosceles deserta Spider Venom Induces NF-κB-Dependent Chemokine Production by Endothelial Cells

BACKGROUND Loxosceles spider evenomation in man frequently results in disfiguring necrotic skin lesions. Recent studies suggest that several proinflammatory mediators participate in lesion development. We have observed that Loxosceles deserta venom induces production of the chemokines interleukin-8, growth-related oncogene alpha, and monocyte chemoattractant protein-I by human umbilical vein endothelial cells. Members of the Rel/Nuclear factor (NF)-kappaB family of transcription factors are important regulators of many genes involved in immune and inflammatory responses. We hypothesized that Loxosceles-venom-induced chemokine expression in human umbilical vein endothelial cells is mediated by NF-kappaB. METHODS Human umbilical vein endothelial cell monolayers were exposed to activating concentrations of Loxosceles deserta venom. Nuclear extracts of these monolayers were analyzed by electrophoretic mobility shift assay. A direct cause and effect linkage between NF-kappaB activation and chemokine expression by Loxosceles venom was established through examination of the effect of SN50 on interleukin-8 and monocyte chemoattractant protein-1 production using a whole-cell enzyme immunoassay. SN50 is a cell-permeable peptide that specifically blocks cytosolic to nuclear translocation of NF-kappaB. Furthermore, the venom-induced synthesis of chemokine mRNAs was investigated by RNase protection assays. RESULTS Loxosceles deserta venom induces the activation of NF-kappaB in human umbilical vein endothelial cells. Antibodies to p50 and p65, but not to p52, c-Rel, or Rel B, induce supershifts of the DNA-protein complexes formed by oligonucleotide probes and nuclear extracts from venom-activated human umbilical vein endothelial cells. SN50 peptide inhibits NF-kappaB translocation and interleukin-8 and monocyte chemoattractant protein-1 production in activated human umbilical vein endothelial cells. CONCLUSIONS Loxosceles deserta venom induces synthesis of interleukin8 and monocyte chemoattractant protein-1 mRNAs in human umbilical vein endothelial cells. The expression of chemokines occurs via an NF-kappaB-dependent pathway.

Postmortem acetaminophen pharmacokinetics: An experimental study of site and time-dependent concentration changes

Postmortem blood drug concentrations are obtained routinely for assessment of the cause of mortality. However, the relationship of postmortem drug concentration to blood concentrations at the time of death remains poorly characterized. Using Ketamine sedation, 10 New Zealand white rabbits were sacrificed 20 minutes after oral gavage with liquid acetaminophen 160 mg/kg as a model drug. Blood samples were obtained from peripheral (femoral vein) and central sites (heart & inferior cava) over time and compared with heart blood concentrations obtained at the time of sacrifice. The mean +/- SE antemortem acetaminophen concentration was 63.1 +/- 14.6 mcg/ml. Postmortem central blood concentrations were as follows: T = 3 h: 200.8 +/- 129.2 micrograms/mL, T = 6 h: 100.8 +/- 39.6 micrograms/mL and T = 12 h: 480.8 +/- 128.8 micrograms/mL. Postmortem peripheral site results were: T = 3 h: 50.2 +/- 21.4 micrograms/mL, T = 6 h: 100.8 +/- 18.1 and T = 12 h: 117.7 +/- 37.2 micrograms/mL. Overall, blood acetaminophen concentrations increased significantly over time for central sampling sites. Drug concentration increases seen in the central sampling sites were several times higher than that seen in peripheral blood. Blood samples taken from peripheral sites did not alter significantly. The results of this controlled study were consistent with previous autopsy case series and case reports suggesting that postmortem drug concentrations do not reflect premortem values. Variables affecting postmortem drug concentrations include both postmortem sampling time and anatomic blood collection site.

Blood Lead Concentrations of Children in the United States: A Comparison of States Using Two Very Large Databases

Objectives To determine whether there are substantial differences by state between 2 large datasets in the proportion of children with elevated blood lead levels (BLLs); to identify states in which the percentage of elevated BLLs is high in either or both datasets; and to compare the percentage of elevated BLLs in individual states with those of children living in Flint, Michigan, during the months when these children were exposed to lead‐contaminated drinking water. Study design Tables of BLLs for individual states from the Quest Diagnostics and the Centers for Disease Control and Prevention datasets for 2014‐2015, containing more than 3 million BLLs of young children < 6 years old, were constructed to compare the Quest Diagnostics and Centers for Disease Control and Prevention data with one another and with BLLs available for Flint children for 2014‐2015. Results For some states, the percentages of BLLs ≥5.0 &mgr;g/dL are similar in the 2 datasets, whereas for other states, the datasets differ substantially in the percentage of BLLs ≥5.0 &mgr;g/dL. The percentage of BLLs ≥5.0 &mgr;g/dL is greater in some states in both datasets than observed in Flint when children were exposed to contaminated water. Conclusion The data presented in this study can be a resource for pediatricians and public health professionals involved in the design of state programs to reduce lead exposure (primary prevention) and identify children with elevated BLLs (secondary prevention).

Blood Lead Levels of Children in Flint, Michigan: 2006-2016

Objective We evaluated the increases in blood lead levels (BLLs) observed in young children in Flint, Michigan, during their exposure to corrosive Flint River water during the years 2014 and 2015 and compared their BLLs to those of Flint children measured during the years 2006‐2013 and 2016. Study design This was a retrospective study design using BLLs extracted from databases from 2006 to 2016. We analyzed a population sample of 15 817 BLLs from children aged ≤5 years with potential exposure to contaminated Flint River water. Percentages of BLLs ≥5.0 &mgr;g/dL and geometric mean (GM) BLLs were analyzed over time. Results A significant decline in the percentages of BLLs ≥5.0 &mgr;g/dL from 11.8% in 2006 to 3.2% in 2016 was observed (P < .001). GM ± SE BLLs decreased from 2.33 ± 0.04 &mgr;g/dL in 2006 to 1.15 ± 0.02 &mgr;g/dL in 2016 (P < .001). GM BLLs increased twice: from 1.75 ± 0.03 &mgr;g/dL to 1.87 ± 0.03 &mgr;g/dL (2010‐2011) and from 1.19 ± 0.02 &mgr;g/dL to 1.30 ± 0.02 &mgr;g/dL (2014‐2015). Overall, from 2006 to 2016, there was a 72.9% decrease in the percentage of children with BLLs ≥5.0 &mgr;g/dL and a 50.6% decrease in GM BLLs. Conclusion These findings suggest that the 11 year trend of annual decreases in BLLs in children in Flint, Michigan, reversed to a degree consistent with random variation from 2010 to 2011, and again during the exposure to Flint River water in 2014‐2015. Historically, public health efforts to reduce BLLs of young children in Flint have been effective over the 11‐year period studied.