Post-resuscitation hemodynamics and relationship to the duration of ventricular fibrillation

OBJECTIVE: We have observed consistent hemodynamic patterns after restoration of spontaneous circulation (ROSC) after ventricular fibrillation (VF) cardiac arrest. We sought to characterize the time-course of these patterns, and to determine whether these differed based on duration of the VF insult. METHODS: We performed a retrospective review of data from a randomized animal experiment that was conducted in an AAALAC-approved animal laboratory. We used mixed-breed domestic swine of either sex. Animals were anesthetized and instrumented for continuous recording of ECG and blood pressures. VF was induced electrically and allowed to progress for various times ranging from brief (22s) to moderate (less than 3min) to prolonged (3-10min). All animals were initially shocked (150J) up to three times. If ROSC was not achieved on the three initial shocks, a standardized treatment protocol was followed. We defined cardiovascular collapse as a SBP<90mmHg sustained for 1min. For statistical purposes, we classified animals as having VF of <3min, or >3min duration. Data were analyzed with Fisher's exact test and survival analysis. RESULTS: A hyperdynamic phase, consisting of very high-blood pressures and tachycardia, was seen in all animals immediately after ROSC. This lasts from 1 to 4min. Post-resuscitation cardiovascular collapse occurred in 2/7 (29%) animals in the <3min group and 13/14 in the >3min group (93%) p=0.006. Onset of cardiovascular collapse was highly related to duration of VF (log-rank p=0.004). CONCLUSIONS: There are two distinct phases of hemodynamic change after resuscitation of VF. The first phase is a brief hyperdynamic phase. The second phase is either stabilization or cardiovascular collapse. When VF is brief, blood pressures often return to normal without exogenous support. When VF was prolonged animals were rescued with exogenous pressor. Healthcare providers should be prepared to provide pressor support for patients having ROSC after prolonged VF.     

Desmoplastic trichoepithelioma with pseudocarcinomatous hyperplasia: a report of three cases

We report three cases of desmoplastic trichoepithelioma (DTE) with overlying pseudocarcinomatous hyperplasia. All three cases developed on the face of patients in their second decade. In spite of their young age, a diagnosis of squamous cell carcinoma was considered for each case, given the unusual juxtaposition of these two well‐known simulators of malignancy. Awareness of this potential association may avert a misdiagnosis of malignancy.     

Interactive effects of parity and pup stress on the maternal behavior of Rattus norvegicus

Litters of primiparous and multiparous rat mothers received 0, 2, or 5 min of cold stress for the 1st 5 days postpartum. Primiparae showed increasing maternal responsiveness over the treatment period. Multiparae were initially maternally responsive to moderate stress cues from pups, but habituated to them over days. From Days 6 to 20, when pups were not stressed, lactation behavior of stressed groups declined in primiparous mothers but not in multiparous mothers.     

Modeling of the dielectric properties of trabecular bone samples at microwave frequency

In this paper, the dielectric properties of human trabecular bone are evaluated under physiological condition in the microwave range. Assuming a two components medium, simulation and experimental data are presented and discussed. A special experimental setup is developed in order to deal with inhomogeneous samples. Simulation data are obtained using finite difference time domain from a realistic sample. The bone mineral density of the samples are also measured. The simulation and experimental results of the present study suggest that there is a negative relation between bone volume fraction (BV/TV) and permittivity/conductivity: the higher the BV/TV, the lower the permittivity/conductivity. This is in agreement with the recently published in vivo data.     

The relationship between oxygen and adenosine in astrocytic cultures

Brain tissue oxygenation affects cerebral function and blood flow (CBF). Adenosine (Ado), a purine nucleoside, moderates neuronal activity, and arterial diameter. The cellular source of Ado in brain remains elusive; however, astrocytes are a logical site of production. Using astrocytic cultures, we tested the hypothesis that astrocytic derived Ado reflects cerebral oxygenation. We found that during alterations in pO₂, extracellular levels of Ado [Ado]_e changed rapidly. Graded reductions of oxygen tension revealed that[Ado]_e reached 10⁻⁷ M to 10⁻⁶ M with a pO₂ of 30–10mmHg, comparable with [Ado]_e and oxygen levels found in brain tissue during normoxemia. Higher O₂ levels were associated with a depression of [Ado]_e. Under conditions of low pO₂ (pO₂ ≤ 3 mmHg), inhibition of extracellular catabolism of adenosine monophosphate (AMP) prevented an increase of [Ado]_e and resulted in a rise in [AMP]_e. The rise in [AMP]_e preceded the increase in [Ado]_e. In the presence of nucleoside transporter inhibitors, accumulation of [Ado]_e persisted. On the basis of our studies in culture we conclude that astrocytes are a significant source of Ado and that during hypoxia, the changes in [Ado]_e are in a range to affect both neuronal activity as well as CBF. © 2010 Wiley‐Liss, Inc.     

High prevalence rate of Entamoeba histolytica asymptomatic infection in a rural Mexican community

The frequency of Entamoeba histolytica and Entamoeba dispar infection was analyzed in a rural community in the state of Morelos, Mexico, using polymerase chain reaction (PCR). Sociodemographic variables as risk factors for the infection were assessed. Results highlighted the number of individuals with intestinal parasites (43.1%) in the community, indicating extensive fecalism. A high frequency of E. histolytica asymptomatic infection, higher than E. dispar infection (13.8% versus 9.6%), was detected by PCR. Anti-amebic antibody levels (IgG) in serum and saliva (IgA) samples were not associated with E. histolytica intestinal infection. These findings suggest a predominant distribution of E. histolytica strains of low invasive potential in this community.     

Large variation in detection of histidine-rich protein 2 in Plasmodium falciparum isolates from Colombia

Most rapid diagnostic tests (RDTs) available use histidine-rich protein 2 (HRP2) as a target. However, it has been reported that sequence variations of this protein affects its sensitivity. Currently, there is insufficient evidence for HRP2 variability in Plasmodium falciparum isolates from Colombia and its relationship with RDT performance. To determine possible geographic differences and their effects on the performance of RDTs, 22 blood samples from patients with P. falciparum malaria from Tumaco and Buenaventura, Colombia were assessed by measurement of HRP2 concentration by an HRP2 enzyme-linked immunosorbent assay, RDTs, and thick blood smear. Statistical analysis showed an association between RDT performance and HRP2 concentrations. No significant difference was found between locations. A large variation of antigen concentration in samples was found at same parasitemia. In contrast to previously reports, there was no correlation between initial parasitemia and HRP2 concentration. Our results indicate that antigen quantity should be studied more carefully because the sensitivity of the RDT is affected more by antigen concentration than by parasitemia.