Self-Cognizant Bionic Liquid Sensor for Pathogen Diagnosis

As observed in the outbreaks of SARS and swine flu, as well as many other infectious diseases, the huge volume of human traffic across numerous enclosed public venues has posed immense challenges to preventing the spread of communicable diseases. There is an urgent need for effective disease surveillance management in public areas under pandemic outbreaks. The physicochemical properties associated with ionic liquids make them particularly suited for molecular communications in sensing networks where low throughput is quite adequate for pathogen detection. This paper presents a self-cognizant system for rapid diagnosis of infectious disease using a bionic sensor such that testing can be supported without collecting a fluid sample from a subject through any invasive methods. The system is implemented for testing the performance of the proposed bionic liquid sensing network.

Development and feasibility of a modified Fugl-Meyer lower extremity assessment for telerehabilitation: a pilot study

Background

The majority of stroke survivors experience motor impairment which benefits from rehabilitation treatment. Telerehabilitation, remote delivery of rehabilitation services, is a possible solution providing access to rehabilitation for stroke survivors living in rural areas or in situations like the COVID-19 pandemic where face-to-face treatment may be risky. However, valid and reliable motor impairment measures have not yet been established over a telerehabilitation platform. The Fugl-Meyer (FM) lower extremity assessment is widely used clinically and in research. Thus, the aim was to develop a modified FM for telerehabilitation (FM-tele) and assess the feasibility and preliminary agreement of FM-tele scores with the FM.

Methods

Three phases were employed: phase 1 development, phase 2 feasibility, and phase 3 preliminary agreement. Literature review and consultation with clinicians were employed to develop the FM-tele. Community-dwelling individuals with stroke and FM evaluators were consulted to provide feedback via questionnaires on the feasibility of the FM-tele. To assess the preliminary agreement of the FM-tele, individuals with stroke participated in two sessions, one in-person and one via telerehabilitation. The standard version of the FM was administered during the in-person session. The FM-tele was administered in both sessions.

Results

From phase 1, clinician consultation identified the following key principles: safety of the client, clear lower extremity visualization, and minimization of position changes which guided FM-tele development (n = 7). Feasibility was established in phase 2 where participants with stroke indicated that they felt safe and experienced ease following the standardized instructions, despite some technological concerns (n = 5). FM evaluators agreed that participants were safe and indicated effective standardized instructions. Phase 3 (n = 5) indicated preliminary agreement of the FM-tele compared with the FM.

Conclusions

Participants with stroke and clinical consultation indicated the FM-tele developed for telerehabilitation is feasible. A lower extremity motor assessment tool for telerehabilitation is urgently needed for stroke survivors living in rural areas or when face-to-face visits are impossible. This pilot study provides preliminary support for a future study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-021-00862-8.

Knowledge, attitudes and binge drinking among urban Chinese university students in Hong Kong

Background

Although dormitory residents have been identified as a high-risk group for alcohol misuse in Chinese university settings, the factors associated with their drinking behaviors has not be characterized.

Methods

A cross-sectional study was conducted among hostel residents in two Hong Kong universities (n = 1455) using self-administered, anonymous surveys. In addition to examining the knowledge levels and drinking-related attitudes, we examined the factors associated with binge drinking in this population using multivariable regression analysis.

Results

Among university dormitory residents, the prevalence of past-month binge drinking was 26.8% among males and 12.8% among females. It was noted that although respondents demonstrated attitudes conducive towards alcohol-free socialization, they exhibited low levels of alcohol-related knowledge (mean knowledge score: 3.3/ 10, SD = 2.0). While about 59% were aware that alcohol is a carcinogen and that some medications should not be taken with alcohol, only 10.4% were familiar with symptoms of alcohol poisoning and only 23% were familiar with relative amounts of alcohol in different beverage categories. Of the respondents the factors independently associated with past-month binge drinking were: male sex, older age, full-time hostel residence, drinking roommates, drinking romantic partner, participation in drinking games, and having pro-alcohol attitudes (OR ranging from 1.33-3.69). Alcohol-related knowledge was not associated with binge drinking.

Conclusions

Although southern China is a low alcohol consumption area, binge drinking is common among university residents and requires multi-prong interventions. Heavy drinking is a neglected health problem among urban Chinese university students. Interventions targeting binge drinkers need to counteract pro-alcohol attitudes and peer effects. Increasing alcohol knowledge may additionally help to reduce alcohol-related harms in this age group.

Key messages

Urban Chinese university dormitory residents demonstrate low levels of alcohol knowledge. Pro-alcohol attitudes and peers effects need to be addressed in university anti-binge drinking interventions.

Second-hand harms of alcohol use in urban Chinese university students: A study from Hong Kong

Background

Although second-harms alcohol harms, harms caused by the drinking of others, may contribute significantly to the public health burden of alcohol, these harms are an understudied area of public health research. This study aims to examine second-hand alcohol harms in among urban Chinese university students residing on campus who are were previously identified as a high risk group for alcohol misuse.

Methods

A cross-sectional study was conducted among hostel residents in two Hong Kong universities (n = 1455) using self-administered, anonymous surveys. We examined the prevalance and the factors associated with second-hand alcohol harms this population using multivariable regression analysis.

Results

Approximately 2/3 of the university residents experienced at least one second-hand drinking harm in the past year while 1/5 experienced 4 or more harms. The harms reported were: 1) inconveniences/disturbances (46.2%), psychological distress/anxiety/depression (32.9%), home arguments (28.3%), conflicts/arguments/insults in public (25.3%), worsened productivity/academics (22.2%), property damage/monetary loss (13.2%), accidents/injury/assault (11.7%) and having to deal with authorities/law enforcement (11.5%). Only 9.1% reported these harms to authorities. Participation in drinking games (OR = 1.44), having drinking roomates (OR = 1.37) or drinking romantic partner (OR = 1.89) were independently associated with likelihood of second-hand alcohol harms (p < 0.05).

Conclusions

Although southern China is a low alcohol consumption region, there is a high prevalence of second-hand alcohol harms among university dorm residents. Universities in the region should rectify the near absence of alcohol-related topics in university health promotion.

Key messages

Harms from the drinking of others is a commonplace but underappreciated phenomenon among university campus residents. University health promotion in the region should include alcohol harms reduction topics.

Comparative Analysis of Gait Speed Estimation Using Wideband and Narrowband Radars, Thermal Camera, and Motion Tracking Suit Technologies

Research has shown that cognitive and physical functioning of older adults can be reflected in indicators such as walking speed. While changes in cognition, mobility, or health cause changes in gait speed, often gradual variations in walking speed go undetected until severe problems arise. Discrete clinical assessments during clinical consultations often fail to detect changes in day-to-day walking speeds and do not reflect walking speeds in everyday environments, where most of the mobility issues happen. In this paper, we compare four walking speed measurement technologies to a GAITRite mat (gold standard): (1) an ultra wideband radar (covering the band from 3.3 GHz to 10 GHz), (2) a narrow band 24-GHz radar (with a bandwidth of 250 MHz), (3) a perception Neuron Motion Tracking suit, and (4) a thermal camera. Data were collected in parallel using all sensors at the same time for 10 healthy adults for normal and slow walking paces. A comparison of the sensors indicates better performance at lower gait speeds, with offsets (when compared to GAITRite) between 0.1 and 20% for the ultra wideband radar, 1.9 and 17% for the narrowband radar, 0.1 and 38% for the thermal camera, and 1.7 and 38% for the suit. This paper supports the potential of unobtrusive radar-based sensors and thermal camera technologies for ambient autonomous gait speed monitoring for contextual, privacy-preserving monitoring of participants in the community.

Fatty acid profile differs between organic and conventionally produced cow milk independent of season or milking time

Differing amounts of fresh forage and concentrates fed, and level of input contributes to the differences reported in fatty acid (FA) composition of organic and conventionally produced cow milk. In many previous studies designed to investigate this phenomenon, comparisons were made between grazed organic cows and housed conventional cows. In the present study, we have investigated differences between organic and conventional milk produced using year-round pasture grazing, as practiced in New Zealand. The FA composition was determined in milk sampled at morning and evening milking in both spring and autumn. Samples were taken from 45 cows from the Massey University organic herd and compared with 50 cows from the corresponding conventional herd grazed and managed similarly at the same location. Forty-three out of 51 analyzed FA were influenced by season, whereas 28 were different between production systems. In addition, one-half were also different due to time of milking. Levels of linoleic acid and α-linolenic acid were higher in organic milk, whereas conjugated linoleic acid (CLA) and vaccenic acid were higher in conventional milk. The first 3 FA (linoleic acid, α-linolenic acid, and CLA) were more abundant in milk harvested during autumn, and the CLA concentration was also significantly influenced by time of milking. Our results confirm reports that the FA profile is affected by season and time of milking, and we also showed an effect due to the production system, when both sets of cows were kept continuously on pasture, even after taking milking time and seasonal effect into account.

Effects of liquid nitrogen cryotherapy and bone grafting on artificial bone defects in minipigs: a preliminary study

Liquid nitrogen cryotherapy has been advocated as an adjunct in the enucleation and curettage of locally aggressive lesions of the jaws. Simultaneous autogenous bone grafting has also been advocated to accelerate bone formation and reduce morbidity. There is, however, relatively little scientific basis for either of these hypotheses. In this study, nine Yucatan minipigs had artificial defects created in the mandible, which were treated with liquid nitrogen spray. Half of the defects were grafted with autogenous bone from the chin and half were closed primarily. Two animals were sacrificed 3 days postoperatively to measure the width of necrosis and the rest were sacrificed at 3 months to assess healing and new bone formation. It was found that drilling the artificial defects alone caused bone necrosis for a mean depth of 0.09 mm. Liquid nitrogen cryospray caused a mean depth of bone necrosis of 0.82 mm (range 0.51-1.52 mm). The defects that were bone grafted healed well clinically. Defects not bone grafted showed a 50% rate of wound breakdown and sequestrum formation with delayed healing. Vital staining showed a non-significantly greater rate of bone formation in the grafted defects. Digitally superimposed radiography showed a non-significantly greater bone density in the non-grafted defects at 3 months postoperatively. It appears that liquid nitrogen cryospray does devitalize an area of bone around defects in the mandible. The width of necrosis is usually less than 1 mm and subsequent healing is enhanced by autogenous bone grafting. This has clinical implications.

[The development and identification of animal osteoblasts from bone marrow culture]

This study was aimed to evaluate a modified method for animal osteoblast marrow culture on the basis of previously published method. The marrow mononuclear cells(MMNC) in femoral bone-marrow of SD rat were gained with Ficoll-Hapaque centrifuge, which were then cultured in 5 x 10(5) cells/cm3 on the 96-well culture plates with RPMI 1640 medium containing 30% horse serum in a humidified atmosphere of 5% carbon dioxide at 37 degree Celsius. The medium was changed every three days. Cultured cells were identified with inverted microscopy for observing the shape of living cells, and with Wright-Geimsa mixture stain and Alkaline phosphatase (ALP) stain. In order to avoid false positive reaction, we caused damage to the ALP in cultured cells and stained the cells with ALP again for comparison. The results of inverted microscopy showed that the small spherical mononuclear cells became polygonal, spindle-shaped or squamous successively from the fifth day onward. Wright-Geimsa staining showed the specific property of osteoblast. ALP stain positive reaction was between "2+" and "3+", then ALP stain negative reaction was noticed after the damage to ALP. These data demonstrated that MMNC in SD rat could become osteoblast in RPMI 1640 medium containing 30% horse serum. The modified osteoblast marrow culture method has the advantages of short time, less risk of contamination and higher efficiency.

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

Effect of adult microsurgical varicocelectomy on testicular volume

OBJECTIVES

To re-examine the potential influence of varicocelectomy on testicular volume using scrotal ultrasonography, because it has been reported that total testicular volume (assessed by physical examination) increases after adult varicocele ligation.

METHODS

A retrospective review of the testicular volume and semen parameters of 61 men who underwent microsurgical varicocelectomy between 1996 and 1998 was performed. Ultrasound-derived testicular volumes and total motile sperm counts were compared before varicocelectomy and at a mean of 7.2 months postoperatively.

RESULTS

Bilateral varicocelectomy was performed in 22 men; 39 men underwent a left-sided procedure only. Overall, no significant change was found in the mean total testicular volume after varicocelectomy compared with preoperatively (24.0 versus 23.9 mL, respectively; P = 0.74). Similarly, the testicular volumes did not change significantly after left or bilateral varicocelectomy (P >0.05). Overall, the mean total motile sperm count increased significantly after varicocelectomy (17. 9 to 25.4, P = 0.05).

CONCLUSIONS

This was the first study to examine the effect of adult varicocelectomy on testicular volume using ultrasound-derived measurements of volume. Unlike previous findings, our data suggest that although adult varicocelectomy improves semen quality in most infertile men, it does not result in a significant increase in testicular volume.

A protective role for protease-activated receptors in the airways

The protection of cells in the upper intestine against digestion by pancreatic trypsin depends on the prostanoid prostaglandin E2 (PGE2) and is mediated by protease-activated receptors in the epithelium. As the airway epithelium is morphologically similar and also expresses one of these receptors, PAR2, and is a major source of PGE2, we reasoned that bronchial epithelial PAR2 might also participate in prostanoid-dependent cytoprotection in the airways. Here we show that activation of PAR2, which co-localizes immunohistochemically with trypsin(ogen) in airway epithelium, causes the relaxation of airway preparations from mouse, rat, guinea-pig and humans by the release of a cyclooxygenase product from the epithelium. This physiological protective response in isolated airways also occurred in anaesthetized rats, where activation of PAR2 caused a marked and prolonged inhibition of bronchoconstriction. After desensitization of PAR2, the response to trypsin recovered rapidly by mechanisms dependent on de novo synthesis and trafficking of proteins. Our results indicate that trypsin released from the epithelium can initiate powerful bronchoprotection in the airways by activation of epithelial PAR2.

An analysis of sports knee evaluation instruments

This study examined four commonly used sports knee evaluation instruments to establish normative data. A total of 91 volunteers who had not sought treatment for knee pain or any other knee complaint at any time in the past underwent a detailed medical history and examination of both of their knees. Three numerical systems (Feagin and Blake Knee Score, Lysholm Knee Score, and the Hospital for Special Surgery Knee Disability Assessment) and one nonnumerical system (the International Knee Documentation Committee Quick Knee Profile) were evaluated. A significant difference in the proportion of knees with excellent/normal ratings was seen among the four evaluation systems (P<.0001): Hospital for Special Surgery Knee Disability Assessment, 99.5%; Feagin and Blake Knee Score, 84.6%; Lysholm Knee Score, 84.1%; and the International Knee Documentation Committee Quick Knee Profile, 50.5%. Results showed that three objective component scores for the International Knee Documentation Quick Knee Profile were significantly lower than all other component scores (P<.05). These components included: overall ligament examination, Lachman, and total AP translation. These data may be useful as a baseline by which investigators studying patients following knee reconstructive procedures have a basis for comparison of their results.

Radiographic verification of pedicle screw pilot hole placement using Kirshner wires versus beaded wires

STUDY DESIGN

Kappa statistics were used to compare the accuracy of two different techniques for verifying pedicle screw pilot hole placement in cadaveric vertebrae.

OBJECTIVE

To determine whether clinicians radiographically detect misplaced pedicle screw holes with greater sensitivity and specificity when beaded wires rather than straight Kirschner wires are used.

SUMMARY OF BACKGROUND DATA

Pedicle screws commonly are used in orthopedic surgery to obtain and maintain spinal stability. Pedicle screws are reportedly misplaced at a rate of 20% to 40%. Radiographic verification is commonly used to place pedicle screw pilot holes, but this technique is known to be less than 100% accurate. Computer-assisted techniques may allow more accurate screw placement, but these techniques require expensive equipment.

METHODS

Pedicle screw pilot holes were drilled into 12 human lumbar and thoracic vertebrae. Some of the holes were misplaced deliberately so that they violated the pedicle walls. Lateral and posteroanterior radiographs of the vertebrae were evaluated by 13 experienced orthopedic spine surgeons and 3 inexperienced observers. At different times, the observers were shown radiographs depicting Kirschner wires or beaded wires placed in the pilot holes. Observers indicated whether they thought the pedicle screw pilot hole violated the pedicle.

RESULTS

The sensitivity and specificity of using posteroanterior or lateral radiographs to detect misplaced pedicle screws were increased when beaded wires were placed in the pilot holes.

CONCLUSIONS

Radiographic evaluation of beaded wires placed in pedicle screw pilot holes can be both sensitive and specific for misplaced screws. The highest sensitivity and specificity were found using posteroanterior radiographs.

Risk factors affecting hospital length of stay in patients with odontogenic maxillofacial infections

PURPOSE

This study identified potential risk factors associated with increasing hospital length of stay (LOS) in patients with odontogenic maxillofacial infections.

PATIENTS AND METHODS

One hundred twenty-eight patients admitted to Brigham and Women's Hospital by the Division of Oral Surgery between October 1, 1984 and March 31, 1995 with a maxillofacial infection of dental origin were retrospectively identified by a medical chart review. Linear regression techniques were used to explain the relationship between patient admission characteristics and LOS. Variables considered included age, gender, infection location, admission white blood count (WBC), admission temperature, antibiotic treatment during hospitalization, attending surgeon, insurance class, operating room use (ORU), and preexisting medical conditions associated with chronic immunosuppression.

RESULTS

The following variables were found to significantly increase LOS: ORU (P = .007), preexisting medical conditions (P < .0001), admission temperature (P = .022), and deep infection (P = .063).

CONCLUSION

LOS is best predicted on the basis of underlying medical conditions and location of the infection.

Dietary polyunsaturated fatty acids enhance the uptake of high-density lipoprotein cholesterol ester by rat adipocytes

Compared with diets high in saturated and monounsaturated fatty acids (20% lard by weight), diets high in polyunsaturated fatty acids (20% sunflower oil) alter the fatty acid composition of rat adipocyte plasma membranes and enhance HDL2 binding. We examined the effect of these two diets on HDL1 and HDL2 apolipoprotein and cholesterol uptake by adipocytes isolated from perirenal and epididymal adipose tissue of male Wistar rats. Consistent with selective cellular uptake. HDL esterified cholesterol uptake was 3-10-fold higher than predicted from HDL apolipoproteins associated with adipocytes. Dietary polyunsaturated fatty acids significantly enhanced apolipoprotein and esterified-cholesterol uptakes from HDL2 by perirenal adipocytes. This effect of dietary fat composition was adipose-region (perirenal greater than epididymal) and HDL-subfraction (HDL2 greater than HDL1) specific. Thus, diet-induced changes known to alter membrane phospholipid composition and increase HDL2 binding are also associated with enhanced HDL2-esterified-cholesterol uptake by adipocytes.

Changes in dietary lipid saturation modify fatty acid composition and high-density-lipoprotein binding of adipocyte plasma membrane

Binding of rat high-density lipoprotein (HDL) to adipocyte plasma membranes appears to be mediated by specific protein-recognition sites, but membrane lipids may also affect these interactions. To study the effect of dietary fatty acid composition on adipocyte-membrane phospholipid composition and HDL binding, male Wistar rats (250 +/- 10 g) were fed diets high in polyunsaturated (20% wt:wt sunflowerseed oil) or saturated and monounsaturated fatty acids (20% lard, by weight). Sunflower-oil vs lard feeding significantly increased the polyunsaturated fatty acid content of membrane diacylglycerophospholipids and the (22:0 and 24:0) content of long-chain fatty acids of sphingomyelin (p less than 0.05) from epididymal and perirenal adipocyte plasma membranes. Concomitant with these changes in membrane phospholipid composition, sunflower-oil vs lard treatment significantly increased the maximum binding capacity (Bmax) of 125I-labeled HDL2 (p less than 0.05). These results show that feeding polyunsaturated fatty acids enhanced HDL2 Bmax of adipocyte plasma membranes, possibly as a consequence of altering the fatty acid composition of membrane phospholipids.

Proteolytic degradation of HDL1 on the fat cell surface is nutritionally regulated

The importance of plasma HDL apolipoprotein concentration as a predictor of atherosclerotic risk is well recognized, yet the processes of HDL modification and degradation in various cells are not clearly understood. We examined the characteristics of HDL1 apolipoprotein degradation and cellular uptake by rat adipocytes and determined the effects of fasting on these processes. Epididymal and perirenal adipocytes were isolated from male Wistar rats (310 +/- 4 g) fed ad libidum and incubated with 5 micrograms of rat 125I-labeled HDL1 (d: 1.07-1.10 g/mL) mL-1 for 2 h at 37 degrees C. Cellular uptake of HDL1 was calculated as the trichloroacetic acid precipitable radioactivity associated with adipocytes following incubation. Intracellular and medium degradation of HDL1 were determined as trichloroacetic acid soluble 125I counts associated with cells and measured in the postincubation medium, respectively. Fifty to sixty percent of cellular uptake and degradation of HDL1 was inhibited by the addition of 25-fold excess unlabeled HDL. HDL1 degradation measured in the medium was 10- to 12-fold greater than cellular uptake of HDL1 apolipoproteins. Intracellular degradation of HDL1 was negligible. The presence of EDTA in the incubation medium reduced HDL1 degradation measured in the medium, but enhanced HDL1 cellular uptake. Conditioned medium separated from cells after 2 h of incubation at 37 degrees C in the absence of HDL and subsequently incubated with 125I-labeled HDL1 for an additional 2 h at 37 degrees C, degraded less than 5% of HDL compared with degradation in the presence of cells. These results suggest that rat adipocytes degrade, or modify, HDL1 particles, possibly by interactions with cell surface proteases.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of massive obesity on low and high density lipoprotein binding to human adipocyte plasma membranes

Adipose tissue is a major cholesterol storage organ in man, and turnover of this slowly exchangeable pool is dependent on low and high density lipoproteins which deliver and remove cholesterol from this site. To determine whether lipoprotein binding is altered in the obese state, we examined the binding of low density lipoprotein (LDL) and high density lipoprotein (HDL2 and HDL3) to purified adipocyte plasma membranes obtained from omental fat depots of massively obese patients (BMI greater than 40 kg/m2) and lean subjects. The specific binding and uptake of 125I-HDL2 and 125I-HDL3 were greater for obese than for lean adipocytes. Scatchard analysis of binding studies using purified adipocyte plasma membranes and varying amounts of labeled HDL2 or HDL3 demonstrated a higher binding affinity (lower Kd) for HDL2 and higher binding capacity (Bmax) value for both HDL2 and HDL3 in obese as compared to lean. 125I-LDL specific binding was somewhat lower in obese than in lean membranes but this difference was not statistically significant. The cholesterol content of isolated omental adipocytes expressed on a cellular basis or as the cholesterol/triglyceride ratio (mg chol/g of lipid) were similar in the obese and lean subjects. Furthermore, 125I-LDL, 125I-HDL2 or 125I-HDL3 specific binding did not correlate with cellular cholesterol content or with cholesterol/triglyceride ratio. These findings indicate that lipoprotein binding to adipocytes is altered in obesity and is characterized by up-regulation of HDL (particularly HDL2) binding with little change in LDL binding. We conclude from this study that obesity has a profound effect on the expression of HDL binding sites in human adipocytes and that LDL and HDL binding in fat cells are regulated differently.

Characterization of high-density lipoprotein binding to rat adipocytes and adipocyte plasma membranes

The interaction of high-density lipoproteins (HDL) with adipocytes is important in the regulation of cellular cholesterol flux. To study the mechanisms of HDL binding and cellular processing, we incubated adipocytes isolated from epididymal and perirenal adipose tissue of male Wistar rats (300 g) with HDL1 (1.07-1.10 g/mL) and HDL2 (1.10-1.14 g/mL) fractions separated from rat plasma by gradient ultracentrifugation. Freshly isolated adipocytes were incubated with 125I-labeled HDL for 2 h at 37 degrees C to determine cell-associated uptake and degradation. Adipocytes from both fat regions showed significant cell-associated HDL1 and HDL2 uptake and very high medium degradation (2- to 6-fold higher than uptake). To assess 125I-labeled HDL binding independent of cellular metabolism, we purified adipocyte plasma membranes from isolated adipocytes and used them in binding assays. Binding of HDL1 and HDL2 in the membrane system was 85-95% specific, sensitive to high NaCl concentrations, and abolished by pronase treatment. In contrast to HDL2 binding, the maximum HDL1 binding to perirenal plasma membranes was significantly higher than its binding to epididymal membranes (7.2 +/- 1.3 vs. 4.4 +/- 0.2 micrograms/mg, n = 6, p less than 0.05). This increment in HDL1 binding to perirenal membranes represented an EDTA- sensitive, calcium-dependent component. These results indicate that HDL binding to adipocyte plasma membranes depends on both adipose tissue region and HDL subtype. The membrane binding characteristics, taken together with the cellular uptake results, suggest that adipocytes bind and metabolize HDL and that this interaction may involve a protein receptor.

Composition, morphology and distribution of high-density lipoproteins in plasma and peripheral lymph: effect of feeding cholesterol and saturated fat

In euthyroid dogs fed a diet rich in cholesterol and saturated fat, the cholesterol concentration in both plasma and peripheral lymph increased progressively with the appearance of HDLc (d 1.006-1.063). This HDLc fraction was heterogeneous and could be separated into 'slow' and 'fast' migrating fractions by Pevikon block electrophoresis. On SDS-polyacrylamide gel electrophoresis, plasma 'slow' HDLc was appreciably enriched in apolipoprotein (apo) E, while plasma and lymph 'fast' HDLc were apo E-poor. In contrast, no apo E was visible in lymph 'slow' HDLc in either plasma or lymph HDL2 fractions (d 1.087-1.21). The interstitial HDL fractions containing apo A-IV ('fast' HDLc and HDL2) were also rich in free cholesterol, implying that apo A-IV-containing particles are involved in reverse cholesterol transport. Plasma and peripheral lymph HDL2 and 'fast' HDLc cholesterol/protein ratios were not different, whereas lymph 'slow' HDLc was 24% that of plasma, indicating that interstitial 'slow' HDLc was poor in cholesterol compared to plasma. This marked reduction in lymph 'slow' HDLc cholesterol suggests that this particle was either selectively retarded from egress by the endothelial barrier, or that interstitial 'slow' HDLc represents a depleted particle involved in the delivery of cholesterol to peripheral tissues. These findings taken together support the hypothesis that interstitial 'slow' HDLc may represent a particle involved in cholesterol ester delivery, in contrast with HDL2 and 'fast' HDLc, which could serve as an efflux acceptor of tissue free cholesterol. This study demonstrates significant heterogeneity of interstitial peripheral lymph lipoproteins compared to plasma lipoproteins, and indicates selective distribution of these particles in the extravascular space.

Interaction of high density lipoprotein with adipocytes in a new patient with Tangier disease

A 56-year-old man, the offspring of a consanguineous first cousin marriage, presented with clinical, morphological, and biochemical features of familial deficiency of high-density lipoproteins (Tangier disease). Of 8 first- and second-degree relatives examined, 4 had either plasma apo A-I or HDL cholesterol concentrations 2 standard deviations below normal population mean on at least 1 occasion. The patient and a majority of his relatives also had high plasma apo B concentrations relative to their levels of cholesterol. Adipose tissue biopsy was undertaken to study HDL interaction with the patients' cells. Specific uptake of HDL3 was demonstrated in adipocytes of this patient, but was decreased relative to a control of similar fat cell size. However, no marked difference in fat cell cholesterol content was observed between the Tangier patient and the control. Thus it appears unlikely that adipocytes play a role in the etiology of Tangier disease.

HDL clearance and receptor-mediated catabolism of LDL are reduced in hypothyroid rats

Hypercholesterolemia associated with hypothyroidism is due partly to increased plasma LDL and partly to increased HDL cholesterol concentrations. The increase in LDL cholesterol has been shown to be secondary to reduced plasma clearance of LDL. To determine which catabolic route was thyroid dependent, the present study examined the effects of hypothyroidism on the receptor-mediated pathway and the 'receptor-independent' pathway of LDL metabolism. Wistar rats (327 +/- 22 g; mean +/- SD) were made hypothyroid by feeding propylthiouracil (0.1%, w/w) and rat 131I-LDL (rLDL; d = 1.019-1.050) and 125I-methylated-LDL (rLDL-CH3) were simultaneously injected i.v. after which the rates of clearance of labelled LDL in plasma were determined over 0-54 h. Total LDL and 'receptor-independent' clearances were represented by clearance of 131I-rLDL and 125I-rLDL-CH3 respectively and the difference between the two represented high affinity receptor-mediated clearance. The data were analyzed using Matthews' model and the fractional catabolic rates (FCR) were calculated. The FCR of rLDL clearance via the receptor-mediated pathway was 0.1042 +/- 0.0112 pools/h (n = 6) in controls vs. 0.0613 +/- 0.0079 pools/h (n = 6) in hypothyroid animals (P less than 0.01). The FCR via the 'receptor-independent' pathway was 0.0642 +/- 0.0040 pools/h (n = 6) in controls vs. 0.0561 +/- 0.0036 pools/h (n = 6) in hypothyroid animals (not significant). The plasma HDL cholesterol concentration was also increased in hypothyroid rats (70.4 +/- 6.7 mg/dl) compared to control (53.3 +/- 3.1 mg/dl) (P less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Modifications and degradation of high density lipoproteins

It is evident that lipoprotein modifications, degradation and clearance from plasma and interstitial compartments involves both cellular and extracellular processing. Cellular uptake of the intact particle as a whole and/or selective removal of constituent apoproteins and lipids by various parenchymal cells goes on continuously. Regulation of these processes undoubtedly varies tissue to tissue and much remains to be clarified in human tissues in vivo. The metabolic effects of chemical, proteolytic, and lipolytic modification of lipoproteins secondary to transient cellular encounters (e.g. during transit through endothelial barriers, or reversible binding to cells) on apolipoprotein clearance remains to be defined. It is likely that multiple post-secretory modifications occur and together represent subtle regulatory events that modulate lipid shuttle functions and cellular targetting properties of HDL particles.

Cardiac and peripheral lymph lipoproteins in dogs fed cholesterol and saturated fat

In normal dogs fed diets containing 1% cholesterol and 30% saturated fat, cholesterol concentration increased in plasma, cardiac lymph, and peripheral lymph. The increase in cardiac lymph cholesterol always exceeded that of peripheral lymph. At plateau, LDL cholesterol increased in plasma and peripheral lymph but not in cardiac lymph; HDL2 cholesterol increased in all compartments and HDLc appeared in plasma (86.6 +/- 22.2 mg cholesterol/dl) with cholesterol feeding. In cardiac and peripheral lymph, a lipoprotein fraction with ultracentrifugal and pevikon electrophoretic characteristics of plasma HDLc (designated HDL 1.063) was isolated and contained 9.4 +/- 1.3 and 11.9 +/- 6.8 mg cholesterol/dl respectively. The lymph/plasma (L/P) ratios of lipoproteins were generally higher in cardiac lymph compared to peripheral lymph. In cholesterol-fed dogs, the L/P ratios of LDL were reduced compared to control dogs while HDL2 was unaffected, indicating selective interstitial distribution of lipoproteins. On agarose electrophoresis, lymph lipoproteins migrated faster than plasma lipoproteins, suggesting subtle changes in the structure and/or composition, findings consistent with the suggestion that lipoproteins undergo modification in the interstitial space. Thus, each interstitial space, as reflected by lymph, has a characteristic mixture of lipoproteins that can be altered by a high cholesterol diet in a manner that is unique to each particular tissue compartment.