Short Communication: Prolonged COVID-19 Infection in a Patient with Newly Diagnosed HIV/AIDS

A 38-year-old male patient presented to the emergency department with fever and dyspnea. Hospitalization was warranted and soon coronavirus disease 2019 (COVID-19) was diagnosed based on a positive SARS-CoV-2-PCR. Over the following weeks his condition gradually worsened, leading to admission at the intensive care unit. Because of unexplained weight loss before admission, a HIV screening was performed. HIV was confirmed and additional tests showed an undetectable CD4+ T cell count, alongside a number of co-infections. Convalescent plasma therapy, which has been shown to be effective in severe humoral immunodeficiency was tried, but was not effective. One week after the HIV diagnosis, antiretroviral therapy was started and finally, 3 months after the initial positive test and after partial recovery of cellular immunity, the COVID-19 virus was cleared. In the end, the patient made a full recovery. Our case demonstrates a prolonged COVID-19 infection in a patient with undiagnosed HIV with severely impaired cellular immunity.

Long-Term Impact of Calcium and Vitamin D Supplementation on Bone Density in HIV+ Patients with Documented Deficiencies

To assess the efficacy of long-term calcium and vitamin D treatment on bone mineral density (BMD) in HIV⁺ patients on combined antiretroviral therapy (cART). A retrospective, single-center cohort study. Between March 2010 and July 2012, 268 HIV⁺ patients were screened for vitamin D and calcium deficiency. Those with proven vitamin D or calcium deficiency received supplementation according to a predefined protocol, and were offered further evaluation of BMD by dual-energy X-ray absorptiometry (DEXA). Calcium and vitamin D status and BMD were assessed at baseline (T₀) and approximately one (T₁) and 4-6 years (T₂) later. Percentual change in BMD of the lumbar spine and hip was compared with reported rates of change in HIV⁺ patients on cART without standard calcium and vitamin D treatment. The prevalence of vitamin D deficiency and calcium deficiency was 46% and 43%, respectively. Thirteen percent of patients had secondary hyperparathyroidism at baseline. DEXA performed in patients with a deficiency revealed osteopenia in 40% and osteoporosis in 8% of patients. The expected long-term change in lumbar spine and hip BMDs at T₂ was -0.7%, -1.5%, and -1.5%, respectively. The measured changes were +2.3%, -0.6%, and -0.6%, respectively. The difference between measured and expected rate of change was significant for the lumbar spine (3.0%, p < .05), but not for the hip. Long-term vitamin D and calcium supplementation improves lumbar spine BMD of HIV⁺ patients with osteopenia or osteoporosis and with proven calcium and/or vitamin D deficiencies. Screening and treatment are recommended to become part of regular care.

Autochthonous Human Case of Seoul Virus Infection, the Netherlands

Orthohantaviruses are a group of rodentborne viruses with a worldwide distribution. The orthohantavirus Seoul virus (SEOV) can cause hemorrhagic fever with renal syndrome in humans and is distributed worldwide, like its reservoir host, the rat. Cases of SEOV in wild and pet rats have been described in several countries, and human cases have been reported in the United Kingdom, France, Canada, and the United States. In the Netherlands, SEOV has previously been found in wild brown rats. We describe an autochthonous human case of SEOV infection in the Netherlands. This patient had nonspecific clinical symptoms of an orthohantavirus infection (gastrointestinal symptoms and distinct elevation of liver enzymes). Subsequent source investigation revealed 2 potential sources, the patient’s feeder rats and a feeder rat farm. At both sources, a high prevalence of SEOV was found in the rats. The virus closely resembled the Cherwell and Turckheim SEOV strains that were previously found in Europe.

Mathematical modeling of gravitational effects on the circulation: importance of the time course of venous pooling and blood volume changes in the lungs

A dip in blood pressure (BP) in response to head-up tilt (HUT) or active standing might be due to rapid pooling in the veins below the heart (preload) or muscle activation-induced drop in systemic vascular resistance (afterload). We hypothesized that, in the cardiovascular response to passive HUT, where, in contrast to active standing, little BP dip is observed, features affecting the preload play a key role. We developed a baroreflex model combined with a lumped-parameter model of the circulation, including viscoelastic stress-relaxation of the systemic veins. Cardiac contraction is modeled using the varying-elastance concept. Gravity affects not only the systemic, but also the pulmonary, circulation. In accordance with the experimental results, model simulations do not show a BP dip on HUT; the tilt-back response is also realistic. If it is assumed that venous capacities are steady-state values, the introduction of stress-relaxation initially reduces venous pooling. The resulting time course of venous pooling is comparable to measured impedance changes. When venous pressure-volume dynamics are neglected, rapid (completed within 30 s) venous pooling leads to a drop in BP. The direct effect of gravity on the pulmonary circulation influences the BP response in the first ∼5 s after HUT and tilt back. In conclusion, the initial BP response to HUT is mainly determined by the response of the venous system. The time course of lower body pooling is essential in understanding the response to passive HUT.

Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method

Reduction in plasma volume is a major contributor to orthostatic tachycardia and hypotension after spaceflight. We set out to determine time- and frequency-domain baroreflex (BRS) function during preflight baseline and venous occlusion and postflight orthostatic stress, testing the hypothesis that a reduction in central blood volume could mimic the postflight orthostatic response. In five cosmonauts, we measured finger arterial pressure noninvasively in supine and upright positions. Preflight measurements were repeated using venous occlusion thigh cuffs to impede venous return and “trap” an increased blood volume in the lower extremities; postflight sessions were between 1 and 3 days after return from 10- to 11-day spaceflight. BRS was determined by spectral analysis and by PRVXBRS, a time-domain BRS computation method. Although all completed the stand tests, two of five cosmonauts had drastically reduced pulse pressures and an increase in heart rate of ∼30 beats/min or more during standing after spaceflight. Averaged for all five subjects in standing position, high-frequency interbeat interval spectral power or transfer gain did not decrease postflight. Low-frequency gain decreased from 8.1 (SD 4.0) preflight baseline to 6.8 (SD 3.4) postflight ( P = 0.033); preflight with thigh cuffs inflated, low-frequency gain was 9.4 (SD 4.3) ms/mmHg. There was a shift in time-domain-determined pulse interval-to-pressure lag, Tau, toward higher values ( P < 0.001). None of the postflight results were mimicked during preflight venous occlusion. In conclusion, two of five cosmonauts showed abnormal orthostatic response 1 and 2 days after spaceflight. Overall, there were indications of increased sympathetic response to standing, even though we can expect (partial) restoration of plasma volume to have taken place. Preflight venous occlusion did not mimic the postflight orthostatic response.

Human cerebral venous outflow pathway depends on posture and central venous pressure

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R(2) = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins.

Dynamic cerebral autoregulation under sinusoidal gravitational loading

Dynamic cerebral autoregulation (CA) has been studied previously using spectral analysis of oscillations in arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). The dynamics of the CA can be modeled as a high-pass filter. The purpose of this study is to compare CA of blood pressure oscillations induced by gravitational loading to CA during resting conditions. We subjected twelve healthy subjects to repeated sinusoidal head-up (0 degrees - 60 degrees) tilts at several set frequencies (0.07 to 0.25 Hz) on a computer controlled tilt table while we recorded ABP (Finapres) and CBFV (transcranial Doppler ultrasound). We fitted the data sets to a high-pass filter model and computed an average time constant (T). Our results show similar phase leads of CBFV to ABPbrain in the rest recording and in sinusoidal tilting, in the studied frequency range. The transfer function gain of the resting spectra increased with increasing frequency, the gain of the tilting spectra did not. Fitting the phase responses of both data sets to a high pass filter model yielded similar time constants.