Microwave sensing of physiological movement and volume change: a review.

The ability non-invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting-receiving antenna, a set of signal-conditioning and processing devices, and a display unit. They operate at continuous-wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001-1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non-conductive walls.     

A POLAROGRAPHIC METHODOLOGY FOR CONTINUOUS NON-DESTRUCTIVE MONITORING OF DRUG RELEASE FROM LIPOSOMES

A simple methodology based on the differential pulse polarography (DPP) was developed for non-destructive monitoring of drug release from liposomes. The methodology was also capable of determining not only the released material that remained free in the liposomal suspension but also the amount of the drug which was eventually adsorbed on the vesicles surface after its release from the liposomes. Based on this methodology the release kinetics of encapsulated chlorothiazide in 5 mg ml^?1 DRV liposomes was studied at 37°C at pH 7.4. The results were compared to those obtained by centrifuging the DRV sample and measuring the free drug in the supernatant solution with UV-spectroscopy. Approximately 70% of the initially encapsulated drug were released within 24 h of which ca. 46% were subsequently adsorbed on vesicles' surface.     

The Effect of Gender-Affirming Hormone Therapy on the Risk of Subclinical Atherosclerosis in the Transgender Population: A Systematic Review

ObjectiveThe impact of gender-affirming hormone therapy (GAHT) on cardiovascular (CV) health is still not entirely established. A systematic review was conducted to summarize the evidence on the risk of subclinical atherosclerosis in transgender people receiving GAHT.MethodsA systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, and data were searched in PubMed, LILACS, EMBASE, and Scopus databases for cohort, case-control, and cross-sectional studies or randomized clinical trials, including transgender people receiving GAHT. Transgender men and women before and during/after GAHT for at least 2 months, compared with cisgender men and women or hormonally untreated transgender persons. Studies reporting changes in variables related to endothelial function, arterial stiffness, autonomic function, and blood markers of inflammation/coagulation associated with CV risk were included.ResultsFrom 159 potentially eligible studies initially identified, 12 were included in the systematic review (8 cross-sectional and 4 cohort studies). Studies of trans men receiving GAHT reported increased carotid thickness, brachial-ankle pulse wave velocity, and decreased vasodilation. Studies of trans women receiving GAHT reported decreased interleukin 6, plasminogen activator inhibitor-1, and tissue plasminogen activator levels and brachial-ankle pulse wave velocity, with variations in flow-mediated dilation and arterial stiffness depending on the type of treatment and route of administration.ConclusionsThe results suggest that GAHT is associated with an increased risk of subclinical atherosclerosis in transgender men but may have either neutral or beneficial effects in transgender women. The evidence produced is not entirely conclusive, suggesting that additional studies are warranted in the context of primary prevention of CV disease in the transgender population receiving GAHT.Systematic Review RegistrationPROSPERO, identifier CRD42022323757.     

Evaluation of sap flow methods to determine water use by cultivated palms

Sustainable management of water resources allocated to palm crops requires reliable tools for measuring palm water use. Thermometric sap flow methods developed for woody dicot plants hold great potential for use in palms, but there have been few investigations to determine whether such methods can be used successfully in ‘woody’ monocots. Here, we evaluate two sap flow methods for measuring whole-plant water use by potted cocos palms (Syagrus romanzoffiana): the Heat Ratio Method (HRM) and the Compensation Heat Pulse Method (CHPM). Measurements of whole-plant water use from the HRM and the CHPM were compared to gravimetric measurements acquired from an electronic balance. Of the two methods, the HRM gave the most accurate results and it most precisely described patterns of transpiration with respect to environmental conditions and leaf morphology. Estimates of total daily water use from the HRM and the balance were highly correlated (R² = 0.92; P < 0.0001) and very near to a 1:1 relationship—an excellent result given the potential for error associated with each method. As expected, the CHPM was seriously limited at low flow rates, but it agreed well with the HRM at higher flow rates (heat pulse velocity >4 cm h⁻¹). Anatomical investigations revealed that vascular bundles in measured palm fronds were evenly distributed and the distance between bundles was comparable in scale to the diameter of probes of HRM sensors, and most likely an order of magnitude smaller than the probable zone of thermal influence for HRM measurements. This contention was supported by results of mathematical modeling suggesting that HRM heat pulse velocities in palm-like sapwood remain largely unaffected by increases in heterogeneity caused by larger xylem vessels and wider interstitial tissues. Although wounding models for heat pulse sap flow methods have not historically catered for the effects of discrete vascular bundles, they are sufficiently approximate given our empirical validations, and we conclude that palm sapwood is thermally homogenous enough for the HRM and the CHPM to be used without modification. Overall, we present strong evidence that heat pulse methods such as the HRM and the CHPM can be used successfully in woody monocots. Finally, we note that the CHPM is likely to perform better in cases of very high flow rates, while the HRM provides more comprehensive monitoring of the usual range of flow rates including at night, early morning and during water deficit.     

Declining Diversity in Natural and Restored Salt Marshes: A 30-Year Study of Tijuana Estuary

Between 1974 and 2004, Tijuana Estuary's natural salt marsh underwent pulse disturbance (an 8-month nontidal period in 1984), which caused the sudden loss of two short-lived halophytes ( Salicornia bigelovii [Sb] and Suaeda esteroa [Se]) and rapid dominance of a productive native succulent ( Sa. virginica [Sv]), plus ramp disturbance that led to gradual codominance by Jaumea carnosa (Jc) (another productive succulent) by 1994. Species richness was high in 1974 (4.2 species/0.25-m² plot), low in 1984 (1.4 species), and not fully recovered by 1994 (3.7 species) or 2004 (3.9 species). Restoration efforts (reseeding former habitat and excavating and planting new sites) did not recover the populations of Sb or Se. In a 1997 project, plantings of these and six other native halophytes survived initially, but by 2005, short-lived species were lost and Sv and Jc dominated, as in the natural marsh. In a 2000 restoration site, planting mortality was high for five species, but Sv recruited voluntarily and dominated by 2005. We attribute recent vegetation changes to frequent catastrophic storms, flooding, and sedimentation, which contrasted strongly with the benign conditions of decades prior to 1974. Sediment blocked tidal channels in 1984 and gradually elevated the marsh plain, degrading the diverse salt marsh and hindering efforts to restore it. Future restoration efforts will require even greater control over sediment inflows plus contouring sites to include natural topographic features that appear critical to sustaining high species richness and evenness.     

Induction of calcium-ion efflux from brain tissue by radiofrequency radiation: Effect of sample number and modulation frequency on the power-density window

Changes have been found in calcium-ion binding to brain tissue exposed in vitro to a specific power density (0.83 mW/cm²) of 147-MHz radiation, amplitude modulated by a 16-Hz sine wave. This report replicates and extends this previous work. To define more precisely the range of effective power densities, two different numbers of samples were treated in a Crawford cell. In one series, four brain tissues were exposed at a time; in the other series, four brain tissues plus six dummy loads were exposed together. While the four-sample configuration produced a narrow power-density window, the ten pseudosample configuration resulted in a broader power-density window. The reason for the sample-number dependence is unresolved, but may be due to interactions between samples and field distortions caused by the close spacing. The ten pseudosample configuration was used to test for the presence and range of a power-density window at a sinusoidal modulation frequency of 9 Hz. The response curve at 9 Hz was essentially identical to the results for 16-Hz sinewave modulation.     

Differences in the electric birefringence of spectrin dimers and tetramers as shown by the fast reversing electric pulse method

The electric birefringence of purified Spectrin has been examined in medium of low ionic strength ai 20°C and for electric fields smaller than 4 × 10⁴ V m^?1. using the reversing electric pulse method. This technique allows study of the permanent and induced dipole electric moment of macromolecules more easily than in measurements using only rectangular pulses. We show that spectrin heterodimers and heterotetramers have different electro-optical properties. The relaxation time of the tetramer (7 μs) is significantly longer than that of the dimer (4.5 μs). Tetramers and dimers have also different polarizability parameters.     

Polymerization in black lipid membranes

A variety of different lipids containing dienoyl groups in the side chains were tested for membrane formation using the planar lipid bilayer approach. One of these lipids formed stable bilayers which could be polymerized using UV-illumination. The influence of the polymerization was studied in monolayers, lipid vesicles and planar bilayers. The stability of the lipid bilayer membranes was increased by polymerization. Thus, the lifetime of the membranes increased from about 1 h to 4–5 h or longer. Furthermore, the specific conductance of unmodified membranes and of carrier-mediated transport is reduced. The transport of lipophilic ions was investigated as a function of polymerization using the charge-pulse method. The absorption of dipicrylamine (DPA^-) is not affected. The translocation of this compound and of tetraphenylborate (B(Ph) ₄ ^- ) showed a strong decrease with polymerization time. The influence of polymerization on the membrane structure may be explained on the basis of a strong viscosity increase in the lipid bilayer membrane.     

Lithium Decreases Membrane-Associated Protein Kinase C in Hippocampus: Selectivity for the α Isozyme

We investigated the effects of lithium on alterations in the amount and distribution of protein kinase C (PKC) in discrete areas of rat brain by using [³H]phorbol 12, 13-dibutyrate quantitative autoradiography as well as western blotting. Chronic administration of lithium resulted in a significant decrease in membrane-associated PKC in several hippocampal structures, most notably the subiculum and the CA1 region. In contrast, only modest changes in [³H]phorbol 12, 13-dibutyrate binding were observed in the various other cortical and subcortical structures examined. Immunoblotting using monoclonal anti-PKC antibodies revealed an isozyme-specific 30% decrease in hippocampal membrane-associated PKC α, in the absence of any changes in the labeling of either the β_(I/II) or γ isozymes. These changes were observed only after chronic (4 week) treatment with lithium, and not after acute (5 days) treatment, suggesting potential clinical relevance. Given the critical role of PKC in regulating neuronal signal transduction, lithium's effects on PKC in the limbic system represent an attractive molecular mechanism for its efficacy in treating both poles of manic-depressive illness. In addition, the decreased hippocampal membrane-associated PKC observed in the present study offers a possible explanation for lithium-induced memory impairment.     

Arterial Stiffness,Carotid Intima-Media Thickness,Endocan, and A Disintegrin and Metalloproteinase With Thrombospondin Type I Motif 9 Levels and Their Relationship With Disease Activity in Patients With Acromegaly With and Without Cardiovascular Risk Factors

ObjectiveCardiovascular complications such as cardiomyopathy and endothelial dysfunction, which are frequently seen in patients with acromegaly, are among the most important causes of morbidity and mortality. In this study, we aimed to investigate arterial stiffness, carotid intima-media thickness, endocan level, and A disintegrin and metalloproteinase with thrombospondin type I motif 9 level and their relationship with disease activity in patients with acromegaly with and without cardiovascular risk factors.MethodsA total of 60 patients with acromegaly—25 with active disease, 26 with well-controlled disease, and 9 with newly diagnosed disease—and 60 age-, sex-, and body mass index (BMI)-matched healthy control subjects were enrolled in this study. All the subjects’ height, weight, BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose (FPG) level, insulin, hemoglobin A1C (HbA1C), C-reactive protein , lipid, endocan, A disintegrin and metalloproteinase with thrombospondin type I motif 9 levels, pulse wave velocity (PWV), and carotid intima-media thickness were measured.ResultsThe SBP, DBP, FPG level, HbA1C level, and PWV of the acromegaly group were higher than those of the control group. In patients with acromegaly with cardiovascular disease (CVD) risk factors, the PWV was higher than that in the control group, and in patients with acromegaly without CVD risk factors, the PWV was similar to that in the control group. In a correlation analysis, a positive correlation was found between PWV and age, BMI, SBP, DBP, FPG level, and HbA1C level in the acromegaly group.ConclusionIn our study, we found that arterial stiffness increased in patients with acromegaly with CVD risk factors and that increased arterial stiffness was associated with hemodynamic (SBP and DBP) and metabolic (BMI, FPG level, and HbA1C level) parameters.