bluuebunny/crossref_metadata_2025 huggingface dataset:
Donor type and 3-month hospital readmission following kidney transplantation: results from the Netherlands organ transplant registry
Authors: Wang Yiman , Heemskerk Martin B. A. , Michels Wieneke M. , de Vries Aiko P. J. , Dekker Friedo W. , Meuleman Yvette
Published: April 2021

Background

Hospital readmission after transplantation is common in kidney transplant recipients (KTRs). In this study, we aim to compare the risk of 3-month hospital readmission after kidney transplantation with different donor types in the overall population and in both young (< 65 years) and elderly (≥65 years) KTRs.

Methods

We included all first-time adult KTRs from 2016 to 2018 in the Netherlands Organ Transplant Registry. Multivariable logistic regression models were used to estimate the effect while adjusting for baseline confounders.

Results

Among 1917 KTRs, 615 (32.1%) had at least one hospital readmission. Living donor kidney transplantation (LDKT) recipients had an adjusted OR of 0.76 (95%CI, 0.61 to 0.96; p = 0.02) for hospital readmission compared to deceased donor kidney transplantation (DDKT) recipients. In the young and elderly, the adjusted ORs were 0.69 (95%CI, 0.52 to 0.90, p = 0.01) and 0.93 (95%CI, 0.62 to 1.39, p = 0.73) and did not differ significantly from each other (p-value for interaction = 0.38). In DDKT, the risk of hospital readmission is similar between recipients with donation after cardiac death (DCD) or brain death (DBD) and the risk was similar between the young and elderly.

Conclusion

A lower risk of post-transplant 3-month hospital readmission was found in recipients after LDKT compared to DDKT, and this benefit of LDKT might be less dominant in elderly patients. In DDKT, having either DCD or DBD donors is not associated with post-transplant 3-month hospital readmission, regardless of age. Tailored patient management is needed for recipients with DDKT and elderly KTRs.
Traumatic ischemic injury in a top of the basilar distribution: a case report
Authors: Gupta Mihir , Yekula Anudeep , Barba David , Pannell J. Scott , Tomlin Jeffrey
Published: April 2021

Background

Top of the basilar syndrome is a rare, heterogeneous disorder that has previously only been described in the setting of acute ischemic stroke in predominantly elderly patients. We present the first reported case of traumatic brain injury (TBI) causing ischemia in a top of the basilar distribution.

Case presentation

A 19-year-old woman suffered an acute subdural hematoma and sustained hypoxemia after being struck by a motor vehicle. Neurosurgical evacuation of the hematoma was undertaken. Magnetic resonance imaging revealed ischemic injury in the midbrain and diencephalic structures fitting a top of the basilar distribution. No associated vascular injury was identified. The patient was eventually discharged in a state of persistent unresponsive wakefulness.

Conclusions

Ischemia in a top of the basilar distribution may occur in the setting of TBI. A high degree of clinical suspicion is required to identify this disorder. Further study of the complex inflammatory microenvironment and associated tissue perfusion dynamics in TBI are needed in order to elucidate the mechanisms underlying ischemic injury patterns, develop management paradigms and predict prognosis.
Esophageal cancer with right vertebral artery variation observed during thoracoscopic esophagectomy: a case report
Authors: Sato Yuta , Tanaka Yoshihiro , Imai Takeharu , Hatanaka Yuji , Okumura Naoki , Matsuhashi Nobuhisa , Takahashi Takao , Yoshida Kazuhiro
Published: April 2021

Background

Variation of the vertebral artery bifurcation is rare. This branching abnormality can cause unexpected vertebral artery damage and bleeding during thoracoscopic esophagectomy. There are few reports of abnormal branching of the vertebral artery associated with neurosurgery but none related to esophagectomy. We report the case together with the results of the evaluation of vertebral artery bifurcation and length in 50 patients with esophageal cancer in our hospital.

Case presentation

Thoracoscopic esophagectomy was performed on a 70-year-old patient with esophageal cancer. During lymph node dissection around the right reccurent laryngeal nerve, an unusual blood vessel was found running along the right subclavian artery. We determined this blood vessel to be the right vertebral artery branching far more centrally than usual. Because this anatomical abnormality was clarified, we could then recognize that the right reccurent laryngeal nerve coursed around the right vertebral artery and the right subclavian artery and thus was running in a larger arch than usual.

Conclusion

Long right vertebral artery may appear in the surgical field of the thoracoscopic esophagectomy. Knowledge of such anatomical variation is important to prevent iatrogenic injury of the right vertebral artery and the right reccurent laryngeal nerve.
Use of prescribing safety quality improvement reports in UK general practices: a qualitative assessment
Authors: Khan Nada F. , Booth Helen P. , Myles Puja , Mullett David , Gallagher Arlene , Evans Catheryn , Thomas Nicholas PB. , Valentine Janet
Published: April 2021

Background

Quality improvement (QI) initiatives are increasingly used to improve the quality of care and reduce prescribing errors. The Royal College of General Practitioners (RCGP) and Clinical Practice Research Datalink (CPRD) QI initiative uses routinely collected electronic primary care data to provide bespoke practice-level reports on prescribing safety. The aim of this study was to explore how the QI reports were used, barriers and facilitators to use, long-term culture change and perceived impact on patient care and practices systems as a result of receiving the reports.

Methods

A qualitative study using purposive sampling of practices contributing to the CPRD, semi-structured interviews and inductive thematic analysis. We interviewed general practitioners, pharmacists, practice managers and research nurses.

Results

We conducted 18 interviews, and organised themes summarising the use of QI reports in practice: receiving the report, facilitators and barriers to acting upon the reports, acting upon the report, and how the reports contribute to a quality culture. Effective dissemination of reports, and a positive attitude to audit and the perceived relevance of the clinical topic facilitated use. Lack of time and failure to see or act upon the reports meant they were not used. Factors influencing use of the reports included the structure of the report, ease of identifying cases, and perceptions about coding accuracy. GPs and pharmacists used the reports to conduct case reviews and directly contact patients to discuss unsafe prescribing and patient medication preferences. Finally, the reports contributed to the development of a quality culture within practices through promoting audit activity and acting as a reminder of good prescribing behaviours, promoting future patient safety initiatives, contributing to continuing professional development and improving local networks.

Conclusions

This study found the reports facilitated individual case review leading to an enhanced sense of quality culture in practices where they were utilised. Our findings demonstrate that the reports were generally considered useful and have been used to support patient safety and clinical practice in specific cases.
A randomized controlled trial on the effect of focal thermal therapy at acupressure points treating osteoarthritis of the knee
Authors: Ho Kevin Ki-Wai , Kwok Anthony Wai-Leung , Chau Wai-Wang , Xia S. M. , Wang Y. L. , Cheng Jack Chun-Yiu
Published: April 2021

Background

Osteoarthritis of the knee is a common degenerative joint disorder in our ageing population. A combination of thermal therapy with a self-management exercise have shown a positive effect in the management of osteoarthritis of the knee. This study aimed to compare the effectiveness of topical heat pack versus focal application of heat therapy at the acupressure points in the treatment of osteoarthritis of the knee.

Methods

A randomized controlled trial was conducted in 76 patients with osteoarthritis of the knee, diagnosed by an experienced orthopedic surgeon. Following inclusion and exclusion selection, patients were randomly allocated to group 1 (Heat pack) or group 2 (Thermal gun). All patients received 30 min of treatment in each session, twice a week for 4 weeks. They also received an education program and taught home knee exercises. Outcome measurements were the visual analog scale (VAS) for pain intensity, muscle power, knee ROM, WOMAC and SF-12v2.

Results

In the Thermal gun group, function and total scores (WOMAC) and Physical Composite Scale (SF-12v2) were significantly improved after 8 sessions. Quadriceps strength was significantly improved after 8 weeks (from 4.42 to 4.63; p = 0.02). In the Heat pack group, flexion was significantly improved after 8 sessions (p = 0.02). Mean VAS scores after Heat pack treatment was consistently better (lower) than mean VAS scores after Thermal gun treatment.

Conclusion

The combination of focal thermal therapy at acupressure points is a viable conservative treatment in osteoarthritis of the knee. The pressure at the acupressure points has a synergistic benefit than topical thermal therapy alone.

Trial registration

ClinicalTrials.gov, NCT04735029

Date of registration: February 2, 2021 (Retrospectively registered)
Correction to: Incidence, clinical features, and outcomes of COVID-19 in Canada: Impact of sex and age
Authors: O’Brien Jacob , Du Kevin Y. , Peng Chun
Published: April 2021

An amendment to this paper has been published and can be accessed via the original article.
Rhodanine-3-acetamide derivatives as aldose and aldehyde reductase inhibitors to treat diabetic complications: synthesis, biological evaluation, molecular docking and simulation studies
Authors: Bacha Mohsinul Mulk , Nadeem Humaira , Zaib Sumera , Sarwar Sadia , Imran Aqeel , Rahman Shafiq Ur , Ali Hafiz Saqib , Arif Muazzam , Iqbal Jamshed
Published: April 2021

In diabetes, increased accumulation of sorbitol has been associated with diabetic complications through polyol pathway. Aldose reductase (AR) is one of the key factors involved in reduction of glucose to sorbitol, thereby its inhibition is important for the management of diabetic complications. In the present study, a series of seven 4-oxo-2-thioxo-1,3-thiazolidin-3-yl acetamide derivatives 3(a–g) were synthesized by the reaction of 5-(4-hydroxy-3-methoxybenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl acetic acid (2a) and 5-(4-methoxybenzylidene)-4-oxo-2-thioxo-1,3-thiazolidin-3-yl acetic acid (2b) with different amines. The synthesized compounds 3(a–g) were investigated for their in vitro aldehyde reductase (ALR1) and aldose reductase (ALR2) enzyme inhibitory potential. Compound 3c, 3d, 3e, and 3f showed ALR1 inhibition at lower micromolar concentration whereas all the compounds were more active than the standard inhibitor valproic acid. Most of the compounds were active against ALR2 but compound 3a and 3f showed higher inhibition than the standard drug sulindac. Overall, the most potent compound against aldose reductase was 3f with an inhibitory concentration of 0.12 ± 0.01 µM. In vitro results showed that vanillin derivatives exhibited better activity against both aldehyde reductase and aldose reductase. The molecular docking studies were carried out to investigate the binding affinities of synthesized derivatives with both ALR1 and ALR2. The binding site analysis of potent compounds revealed similar interactions as were found by cognate ligands within the active sites of enzymes.
Exploring presentation differences in multi-cultural youth seeking assistance for mental health problems
Authors: Shepherd Stephane , Harries Cieran , Spivak Benjamin , Pichler Anne-Sophie , Purcell Rosemary
Published: April 2021

Background

Mental ill-health can impact an individual’s capacity to interact with others, make decisions, and cope with social challenges. This is of particular importance for many Culturally and linguistically diverse (CALD) individuals who may be at various stages of the acculturation process. The increasing diversity of the Australian population necessitates informed and culturally relevant services that meet the needs of a changing demographic. However the extant research on the mental health needs of CALD Australians is limited. This study aimed to further our understanding of the mental health needs of young CALD Australians by exploring the mental health concerns and social factors exhibited by CALD individuals accessing community based youth mental health services in two major cities.

Methods

We performed a series of logistic regression models to ascertain if a concert of factors (i.e., clinical, socio-economic, criminal justice system involvement, child maltreatment, social support) were associated with CALD status

Results

Comparisons across factors revealed no significant differences between groups. A small number of correlates differentiated between CALD and non-CALD participants (mental illness diagnosis during childhood, family history of mental illness/suicide, sensation seeking, sensitivity to punishment, maternal overprotection) however these factors were no longer meaningful after adjustment for multiple comparisons.

Conclusions

In help-seeking mainstream youth populations, cultural differences across clinical and environmental factors appear to be minimal.
Are “Internet+” tactics the key to poverty alleviation in China’s rural ethnic minority areas? Empirical evidence from Sichuan Province
Authors: Yin Xiang , Meng Zhiyi , Yi Xin , Wang Yong , Hua Xia
Published: April 2021

China has made great efforts to alleviate poverty in rural ethnic minority areas and targeted achieving the poverty-alleviation task by the end of 2020. Aba, Ganzi, and Liangshan, three of the poorest ethnic prefectures in Sichuan Province, Southwest China, have all implemented “Internet+” tactics since 2013, which have had the positive effect of increasing family revenues by improving communication infrastructure and encouraging the large-scale use of e-commerce. This paper aims to comprehensively investigate whether “Internet+” tactics play a key role in poverty alleviation in Sichuan’s rural ethnic minority areas and to propose further measures to enhance the efficiency of e-commerce practice. To this end, we conduct an analysis using the framework of classic growth theory and use panel data from 2000 to 2018 to examine the relationship between Communication Infrastructure Investment (CII) and a set of poverty-alleviation indicators, including local GDP growth rate (LGGR), local government revenue (LGR), and per-capita income of residents (PCIR). The results indicate that strengthening CII improves the PCIR and local economic growth, playing a key role in poverty alleviation. However, the stimulation of CII on LGGR and LGR wanes as time passes. More financial and technical actions will be needed to improve the efficiency and quality of current strategies for sustainable development in those areas.
Cryptocurrencies, gold, and WTI crude oil market efficiency: a dynamic analysis based on the adaptive market hypothesis
Authors: Ghazani Majid Mirzaee , Jafari Mohammad Ali
Published: April 2021

This study examined the evolving oil market efficiency by applying daily historical data to the three benchmark cryptocurrencies (Bitcoin, Ethereum, and Ripple), gold, and West Texas Intermediate (WTI) crude oil. The data coverage of daily returns was from August 2015 to April 2019. We applied two alternative tests to examine linear and nonlinear dependency, i.e., automatic portmanteau and generalized spectral tests. The analysis of observed results validated the adaptive market hypothesis (AMH) in all markets, but the degree of adaptability between the data was different. In this study, we also analyzed the existence of evolutionary behavior in the market. To achieve this goal, we checked the results by applying the rolling-window method with three different window lengths (50, 100, and 150 days) on the test statistics, which was consistent with the findings of AMH.
Influence of beam hardening in dual-energy CT imaging: phantom study for iodine mapping, virtual monoenergetic imaging, and virtual non-contrast imaging
Authors: Kanatani Risa , Shirasaka Takashi , Kojima Tsukasa , Kato Toyoyuki , Kawakubo Masateru
Published: April 2021

In this study, we investigated the influence of beam hardening on the dual-energy computed tomography (DECT) values of iodine maps, virtual monoenergetic (VME) images, and virtual non-contrast (VNC) images. 320-row DECT imaging was performed by changing the x-ray tube energy for the first and second rotations. DECT values of 5 mg/mL iodine of the multi-energy CT phantom were compared with and without a 2-mm-thick attenuation rubber layer (~700 HU) wound around the phantom. It was found that the CT density values UH, with/without the rubber layer had statistical differences in the iodine map (184 ± 0.7 versus 186 ± 1.8), VME images (125 ± 0.3 versus 110 ± 0.4), and VNC images (−58 ± 0.7 versus −76 ± 1.7) (p < 0.010 for all). This suggests that iodine mapping may be underestimated by DECT and overestimated by VME imaging because of x-ray beam hardening. The use of VNC images instead of plain CT images requires further investigation because of underestimation.
Reducing Futile Acute Care Services for Terminally Ill Patients With Cancer: The Dignity Project
Authors: Salama Hind , Al Mutairi Nashmia , Damlaj Moussab , Alolayan Ashwaq , Binahmed Ahmed , Salama Hagir , Tlayjeh Haytham , Alhejazi Ayman , Lawrence Myer , Shehata Hussam , Shami Mona , Alkaiyat Mohammad , Jazieh Abdul Rahman
Published: April 2021

PURPOSE:

Patients with terminal diseases frequently undergo interventions that are futile and may be detrimental to their quality of life. We conducted a quality improvement project aimed to reduce the utilization of futile acute care services (ACSs) for patients with cancer treated with a palliative intent.

METHODS:

A multidisciplinary team reviewed the records of terminally ill patients with cancer who died between November 2017 and May 2018, during their admission at our institution. The review aimed to assess the magnitude of improper utilization of ACSs and admission to the intensive care unit (ICU). Lack of timely documentation of the goals of care (GOCs) was the main reason for this problem. We defined timely documentation as the availability of electronic documentation of patients' GOC before the need for ACSs. Interventions were implemented to improve the process; postintervention data were captured and compared with the baseline data.

RESULTS:

After the delivery of staff education and the implementation of mandatory documentation of the GOCs in the healthcare electronic record system, the timely documentation of the GOCs for patients with a palliative intent increased significantly from 59% at baseline to 83% in the postintervention phase. The impact of this intervention led to a decrease in admissions to the ICU from 26% to 12% and an estimated annual cost saving of $777,600 in US dollars.

CONCLUSION:

Our interventions resulted in improved documentation of the GOCs and decrease in the utilization of ACSs including ICU admissions and the associated cost.
Art, Activism, and the Presence of Memory in Palestine
Authors: Abu-Lughod Lila
Published: April 2021

In this interview conducted by Lila Abu-Lughod on October 17, 2020, Palestinian artist Rana Bishara discusses the three artworks that appear on the covers of volume 41 of Comparative Studies of South Asia, Africa and the Middle East, as well as numerous other multidisciplinary and multimedia artworks she has made and exhibited from the 1990s to the present, focusing specifically on art as a form of political activism.
An Analysis of the Postgastrula Differentiation of the Hypomere
Authors: Finnegan Cyril V.
Published: April 2021

An experimental analysis of the competence of the Urodele hypomere for different kinds of mesodermal histogenesis was continued by heteroplastic and homoioplastic transplantations of portions of neurula and tail-bud trunk hypomere to a position overlying the somitic mesoderm in Ambystoma punctatum and Taricha torosa. The major portion of the transplanted hypomere differentiated, in association with the overlying ectoderm (either host or donor), into a loose connectivetissue dermis. The specific characteristics of this connective tissue differed with the age of the donor tissue (older hypomere more rapidly developed the associated homogeneous ground substance) and with the species of the host (all graft tissue on A. punctatum hosts developed more rapidly the loose connective-tissue dermis and then, often, a fibrous connective tissue was formed). The association of donor tissue and host tissue in the ventral somite tip region resulted in host-donor responses which involved both tissues and which gave evidence of further histogenetic competence on the part of the hypomere. Apparently in response to influences of the ventral somite tip, the immediately superficial donor cells increased in number (by mitotic activity and aggregation) and developed an outgrowth from this ‘limb-bud’ mass. Younger ventral hypomere demonstrated greater histogenetic competence in responding to this host influence than did the older hypomere and, in T. torosa, the dorsal hypomere was more competent in this respect than was the ventral hypomere. It was also shown that the development of the outgrowth would not occur in the absence of the superficial somite tissue of the ventral myotome even though an initial mass of donor cells might be produced. Possibly in response to stimulation by the grafted hypomere, the host’s pronephric duct in the graft region increased in size (number of cells constituting the duct wall) and branched (regenerated) with the supernumerary nephric duct passing posteriad along the experimentally created hypomere-somite boundary. Both host and donor cells seemed to be incorporated into this new duct. Responding to tubule induction by the supernumerary pronephric duct, the closely associated ventral somite cells attempted development of mesonephric tubule rudiments. These supernumerary rudiments were more anterior than the normal host rudiments and were noticeably less well differentiated. Such experimentally produced developmental associations deprived the host trunk myotomes of their ventral tips, which resulted in a lack of ventrolateral myotome extension and thus in the subsequent failure of ventro-lateral musculature to appear in the graft region of the host trunk.
Vegetal rotation, a new gastrulation movement involved in the internalization of the mesoderm and endoderm in Xenopus
Authors: Winklbauer Rudolf , Schürfeld Matthias
Published: April 2021

A main achievement of gastrulation is the movement of the endoderm and mesoderm from the surface of the embryo to the interior. Despite its fundamental importance, this internalization process is not well understood in amphibians. We show that in Xenopus, an active distortion of the vegetal cell mass, vegetal rotation, leads to a dramatic expansion of the blastocoel floor and a concomitant turning around of the marginal zone which constitutes the first and major step of mesoderm involution. This vigorous inward surging of the vegetal region into the blastocoel can be analyzed in explanted slices of the gastrula, and is apparently driven by cell rearrangement. Thus, the prospective endoderm, previously thought to be moved passively, provides the main driving force for the internalization of the mesendoderm during the first half of gastrulation. For further involution, and for normal positioning of the involuted mesoderm and its rapid advance toward the animal pole, fibronectin-independent interaction with the blastocoel roof is required.
Some Properties of the Rabbit Blastocyst
Authors: Lutwak-Mann Cecilia
Published: April 2021

A study of certain chemical components of the rabbit blastocyst was carried out using material available at 6, 7, 8, and up to 12 days after copulation. For chemical determinations unimplanted blastocysts were used whole; from the implanted blastocysts the fluid filling the interior was withdrawn by aspiration. The content of nitrogen, chlorides, Na, K, Mg, and Ca was determined. Glucose was identified in yolk-sac fluid and its concentration before and after implantation was determined. The passage from maternal blood into the blastocyst fluid was investigated, during a 30-60-minute interval following parenteral administration, of glucose, C. LUTWAK-MANN—PROPERTIES OF RABBIT BLASTOCYST 13 fructose, sucrose; sulphapyridine, thiocyanate. Under the experimental conditions of this study all these substances, except thiocyanate, passed freely into the fluid of the fully implanted blastocyst 8 days after mating. None, however, was able to penetrate into the unimplanted blastocysts. During the initial phase of implantation glucose entered the fluid more readily than either fructose or sucrose. In hyperglycaemic alloxan-diabetic rabbits the glucose concentration in the blastocyst fluid represented only a fraction of that found in the maternal blood. Data are presented for the distribution of glycogen and phosphorus in the rabbit uterus, –8 days after copulation, at the level of implantation, and in the interimplantation areas.
The Cultivation of the Pituitary of Infantile Rats by the Glass-Rod Technique and the Influence of Grafted Explants on the Growth of Hypophysectomized Hosts
Authors: Martinovitch Petar N.
Published: April 2021

Explanted anterior pituitaries of 13−17-day-old rats survive in watchglasses on glass rods for at least 3 months. In whole expiants of 10−14-day-old animals the posterior lobe (pars nervosa), and probably the pars intermedia as well, survive as long as the anterior lobe. Both the anterior lobe and the pars nervosa survived, when embryo extract was added to the medium, for up to 131 days. Some acidophilic cells, partly degranulated, persist in cultures throughout the whole in vitro life of the explant. Basophils closely resembling the ‘castration cell’ are clearly visible in stained preparations of the explant, but only after 6 to 8 weeks of cultivation. A number of dividing chromophobes have been observed during the first 2 months of cultivations. Anterior pituitaries after cultivation for between 1 and 2 months when grafted into the anterior eye chamber caused young hypophysectomized rats to resume their growth which had been completely arrested. In some explant-transplants the parenchyma of the anterior lobe consists of only one type of cell, namely the chromophobe; in others, some partly granulated acidophils have been found. Basophils have not been observed in transplanted expiants. Anterior pituitaries cultivated in a diluted (liquid) plasma medium retain a remarkably normal appearance for over two months and contain numerous healthy-looking acidophil cells throughout that time. A modification of the glass-rod technique for use with liquid media has been described.
Observations on the Nature of the Relationship between Cell Division and Carbohydrate Metabolism
Authors: O’Connor R. J.
Published: April 2021

From micromanometric measurements made on liver tissue of the chicken embryo, isolated in a glucose-containing medium, estimates have been made of the rate of glucose catabolism ending in acid formation and that utilizing oxygen. The variations undergone by these metabolic processes during normal development have been compared with the variations in mitotic activity of the hepatic cells as determined by the proportion of dividing cells seen in histological sections. The comparison revealed two different associations in the embryonic liver between carbohydrate metabolism and mitotic activity. Before the appearance of glycogen, mitotic activity, the estimated rate of acid production from glucose, and the rate of respiratory glucose utilization decreased in a corresponding manner. After the appearance of glycogen, mitotic activity persisted, but the estimated rates of both metabolic processes fell nearly to zero. Both before and after the appearance of glycogen these relationships of mitotic activity to carbohydrate metabolism differed from those previously recorded for the midbrain and the red-blood cells, which in turn differ one from the other. The suggestion has been made that these differences are consistent with a common dependence of mitotic activity on metabolic reactions leading to pyruvate formation, special consideration being given to the reactions of the hexose monophosphate oxidative route (Dickens, 1953), concerned in the formation of ribose-5-phosphate. This possible dependence is considered to be additional to a dependence of mitotic activity on the energy produced from carbohydrate by the reactions of the tricarboxylic cycle. The implications of such a double dependence of mitotic activity on carbohydrate metabolism have been discussed.
Some Observations on Vitally Stained Rabbit Ova with Special Reference to their Albuminous Coat
Authors: Bacsich P. , Hamilton W. J.
Published: April 2021

The gradual deposition of a homogeneous, jelly-like covering on the rabbit ovum during its passage down the uterine tube was first observed by Cruikshank in 1797. This observation has been confirmed repeatedly by many later workers (Barry, 1839; Bischoff, 1842; Thomson, 1859; Assheton, 1894; Gregory, 1930; and Pincus, 1936). Barry referred to this covering investing the zona pellucida as ‘chorion’, some called it the ‘pro-chorion’, while others (Lenhossek, 1911; Grosser, 1927) simply spoke of a deposit of mucus due to the glandular activity of the tubal epithelium. In the more recent literature (Gregory, 1930; Pincus, 1936) this layer is generally referred to as an ‘albuminous’ coat, probably because of its slight similarity to the covering of a hen’s egg.
A combined physiological and morphological study of the secretory process in the rabbit choroid plexus
Authors: Segal M. B. , Burgess Ann M. C.
Published: April 2021

The ultrastructure of the secreting and non-secreting rabbit choroid plexus has been examined with the electron microscope. Secretion was inhibited by perfusion with an artificial cerebrospinal fluid containing one of the following drugs that have been shown to inhibit CSF formation and also the rate of penetration of sodium ions into the fluid: Ouabain, Diamox, Spirolactone and Amiloride.

Perfusion with Kamovsky’s fixative enabled good preservation of the ultrastructure to be obtained in situ. In the inhibited state, large intercellular spaces, some of them reaching 5 μm diameter, were observed along the length of the intercellular cleft, whilst other regions of the cleft retained normal dimensions, apparently limited by desmosomes. In the normally secreting plexus subject to identical conditions of fixation, no such dilations were seen. This ‘reverse’ system contrasts with the ‘forward’ transporting system found in the gall bladder. These findings are in accordance with the Diamond concept of water transfer for ‘reverse’ systems since, if fluid is moving out of the cleft under the influence of active sodium transport, it could be predicted that no dilation would occur jn the transporting condition. A possible explanation of the mechanism is offered in terms of the high hydrostatic pressure which may exist in the choroidal capillaries which, unlike the rest of the cerebral vasculature, are of the fenestrated type and are thus most likely to be highly permeable.
Adhesive selectivity is exhibited in vitro by cells from adjacent tissues of the embryonic chick retina
Authors: Buultjens T. E. J. , Edwards J. G.
Published: April 2021

Cells from anatomically remote organs of developing embryos do not normally encounter one another. If intercellular adhesive selectivity has a role in determining or maintaining the position of cells in organs, it should be exhibited between cells which are found in close proximity within a single organ. To test this hypothesis, a collecting cell-sheet assay for intercellular adhesive selectivity has been applied to cells from 3 layers of the retina of the embryonic chick. The finding of a modest degree of selectivity of adhesion between cells from the neural retina and choroid supports the hypothesis. The observed selective low adhesiveness for self of the upper surface of pigmented retina epithelium emphasizes the likely morphogenetic significance of the topographical distribution of intercellular adhesiveness.
Quantitative electronic analysis of normal and transformed bhk2l fibroblast aggregation
Authors: Whur P. , Koppel H. , Urquhart Catriona , Williams D. C.
Published: April 2021

The kinetics of cell aggregation in shaking suspension are complex. Consequently most existing forms of assessment are qualitative or semiquantitative. We have used a Coulter counter coupled to a particle size discriminator to describe aggregation more precisely.

BHK21 C13 cells were suspended by light or heavy trypsin/EDTA treatments, and then aggregated at 37 °C. Plots were obtained showing the distribution of cells in 1-50 cell aggregates, from which were calculated the rates of redistribution of cells between aggregates. About half the cells in the initial suspension were not single. During the first 5 min of aggregation single cells and aggregates containing up to 4 cells disappeared into larger aggregates. At later times there was a shift towards a net loss of slightly larger aggregates. Adhesions between single cells were the most common event throughout aggregation, but they declined relatively rapidly with time as adhesions between aggregates became relatively more prominent. The overall rate of adhesions declined 10-fold within 12 min and 100-fold within 90 min.

In contrast to normal fibroblasts, nearly all transformed BHK21 cells in initial suspensions were single, and even by 30 min few single cells had adhered to form aggregates. The initial rate at which adhesions were formed was only about 15% of that of normal cells.

Heavy trypsin/EDTA treatment of normal cells released DNAse-sensitive material which markedly altered the aggregation kinetics. These changes included the disaggregation of small loosely adhering cell clusters coupled with the formation of abnormally large aggregates.

It is suggested that careful preparation of suspensions together with assessment of aggregation on the basis of initial adhesion rate will improve the accuracy and information yield in this type of experiment.
Electrophoretic mobility of microsomes from rat liver
Authors: Blad D. , Winqvist L. , Dallner G.
Published: April 2021

The electrophoretic mobilities of rough and smooth microsomes were studied using free electrophoresis in a sucrose gradient. Rough microsomes have a higher net negative surface charge but removal of the ribosomes decreases their mobility to that of smooth microsomes. Treatment with neuraminidase and phospholipases C and D does not affect the mobility of total smooth microsomes, but this mobility is increased by ∼ 20% after trypsin and papain treatment and by ∼ 12% after phospholipase A treatment. Further treatment of trypsin- digested smooth microsomes with phospholipase C re-establishes the original mobility. This effect is not caused by the removal of lipid phosphate groups, but by the liberation of negatively charged protein species that are normally buried under trypsin-sensitive proteins. Low concentrations of trypsin also solubilize enzyme proteins from smooth liver microsomes of pheno- barbital-treated rats, but the electrophoretic mobility is not increased, indicating structural differences between induced and control membranes.
Freeze-fracture replication and surface sublimation of frozen collagen fibrils
Authors: Stolinski C. , Breathnach A. S.
Published: April 2021

Collagen fibrils from various rapidly frozen mammalian tissues were examined by the technique of straightforward freeze-fracture, freeze-fracture followed by sublimation and surface sublimation technique. Fixed and non-fixed specimens cryoprotected either with glycerol or dimethylsulphoxide (DMSO), as well as non-cryoprotected ones, were examined.

Fibrils were observed either with a banded pattern or as helically twisted strands, and in some cases as a combination of both arrangements. Minimally processed fibrils presented a clearcut banded appearance, while the helical pattern seemed to be associated with the presence of the cryoprotectant, glycerol and DMSO. It is concluded that the banded appearance is in all probability a normal feature of the collagen fibrils in vivo, and that the helical pattern is an abnormal feature resulting from various pretreatments of tissue.
The effects of glutaraldehyde and formaldehyde fixation on the retention and subcellular location of [3H]5-hydroxytryptamine in rabbit platelets: A study using liquid scintillation counting and E.M. autoradiography
Authors: Baker J. R. J. , Pay G. F.
Published: April 2021

The retention and loss of [3H]5-hydroxytryptamine (5-HT) from rabbit platelets during fixation was studied using liquid scintillation counting and quantitative electron-microscopic autoradiography. The results were at variance with previously reported data on human platelets. Following treatment of the platelets with either 2·0% formaldehyde or 2·5% glutaraldehyde for 2 min or 1 h it was found that a significantly increased proportion of the radioactivity was lost from treated as compared with untreated platelets. Using a method of analysis which accounts for cross-scatter of decay particles between cell compartments, electron-microscopic autoradiography revealed that 50 % of the radioactivity following incubation of platelets with [3H]5-HT was associated with dense bodies and 30 % in the cytoplasm when fixation was in formaldehyde or glutaraldehyde. The only major difference in the labelling pattern was that whereas glutaraldehyde appeared to retain no activity in the surface connected system the latter contained 12 % of total retained activity following fixation with formaldehyde.
Light-induced pigment aggregation in cultured fish melanophores: spectral sensitivity and inhibitory effects of theophylline and cyclic adenosine-3′,5′-monophosphate
Authors: Wakamatsu Yuko , Kawamura Satoru , Yoshizawa Toru
Published: April 2021

About 20 % of xiphophorin fish (Xiphophorus maculatus) dermal melanophores which were cultured in monolayer for 5 to 10 days responded to light directly, exhibiting reversible melanosome aggregation within a few minutes. In order to determine the spectral sensitivity for the light-response, absorbance changes due to the light-induced melanosome aggregation were measured on single melanophores in a range of wavelengths from 370 to 550 nm using a recording microspectrophotometer. The melanophores showed maximum sensitivity to a wavelength of about 410 nm and very little to those longer than 500 nm. 10−4 to 10−2 M theophylline and 10−4 M cAMP had inhibitory effects on the light-response.
Electron-microscope study of Dictyostelium discoideum plasma membrane and its modifications during and after phagocytosis
Authors: Ryter Antoinette , Hellio Raymond
Published: April 2021

The study of plasma membrane and phagosome membrane of Dictyostelium discoideum was performed using 2 lectins: concanavalin A (Con A) and Wheat Germ Agglutinin (WGA), and 2 markers of anionic sites: colloidal iron hydroxide (CIH) and cationized ferritin (CF).

These labellings were applied to fixed partially broken cells, which had ingested a large quantity of yeast. They showed that Con A and CF labelled both the outer and inner faces of the plasma membrane, whereas CIH and WGA were deposited on the outer face only. Phagosome membranes displayed the same location as the plasma membrane for Con A, CF and CIH even in very old phagosomes. This suggests that most receptors of these 3 markers were not degraded by hydrolases. In contrast, phagosome membranes of young and old phagosomes did not react with WGA. When labellings were made on yeast phagocytozing cells, the membrane of phagocytic cups was also devoid of WGA, while it was labelled with the 3 other markers. The absence of WGA labelling was not observed during ingestion of bacteria and latex beads, suggesting a specific relationship existed between yeast cells and WGA receptors.
Cell surface localization of 5′AMP nucleotidase in prestalk cells of Dictyostelium discoideum
Authors: Armant D. Randall , Stetler David A. , Rutherford Charles L.
Published: April 2021

5’AMP nucleotidase activity was localized by electron microscopy in Dictyostelium discoideum during cell differentiation. In addition, the activity was assayed by micro enzymic methods in sections dissected from specific cellular regions of lyophilized individuals. The results of the 2 procedures were in agreement, demonstrating that at the culmination stage of development the activity is strikingly localized in the prestalk cells adjacent to the prespore region. The cytochemically stained reaction product appeared only along the plasma membrane of the cells. As prestalk cells migrate into the stalk sheath and undergo differentiation, the activity is rapidly lost. Examination of stained cells at high magnification revealed the product accumulation to be primarily at the cell surface, suggesting that the enzyme functions extracellularly. Occasionally, cells having the morphological appearance of prestalk cells were found within the prespore region. These cells demonstrated 5’AMP nucleotidase activity at their plasma membrane in sharp contrast with neighbouring prespore cells. The strategic localization of 5’AMP nucleotidase may reflect a mechanism for establishing and maintaining regulatory levels of extracellular 5’AMP and/or adenosine during pattern formation in this model system.
Distribution of actively absorbed diffusible sugars in the jejunal epithelium of the rat
Authors: Johnson I. T. , Bronk J. R.
Published: April 2021

Electron-microscope autoradiography, using freeze-dried frozen sections of unfixed tissue, was used to study the distribution of actively transported materials in the jejunal epithelium of the rat in vitro. After a few minutes incubation, the grain density over the organelle-packed interiors of the apical cytoplasm of the columnar absorptive cells was significantly greater than that over the structureless peripheral cytoplasm. This difference in the relative specific activities of the 2 subcellular compartments increased during accumulation of labelled galactose, and decreased as preloaded galactose was washed out of the epithelium. A similar compartmentation was observed in vascularly perfused intestines exposed to labelled galactose from either the mucosal or the serosal sides. These observations suggest the presence of an intracellular mechanism controlling the location and concentration of transported substrates during intestinal absorption.
Pronuclei of heliophrya erhardi matthes during conjugation and their differential association with coated and uncoated microtubules
Authors: Lanners H. Norbert
Published: April 2021

Microtubules surrounding the pronuclei during conjugation of the suctorian ciliate Helio-phrya erhardi can be divided into 2 distinct classes by electron microscopy. Microtubules around the stationary nucleus have a conventional appearance and presumably serve as a skeleton, anchoring that nucleus in its cytoplasmic position. Microtubules surrounding the prospective migratory nucleus are coated with electron-dense material and are in some cases associated with 7-nm filaments. These coated microtubules supposedly function to transport the migratory nucleus into the conjugation partner.
The mode of action of 2,4-D in counter-acting the elongation of carrot cells grown in culture
Authors: Lloyd Clive W. , Lowe Susan B. , Peace Geoffrey W.
Published: April 2021

The growth regulator 2,4-D (2,4-dichlorophenoxyacetic acid) has been used to investigate the inter-relationship between cell elongation and cell division in carrot suspension cells. Maintained in 1 mg/1. 2,4-D, dividing populations of cells remain spheroidal and in clusters. But when subcultured into lower levels or zero, 2,4-D they increasingly elongate at the expense of division. Over the range of 0 to 1·0 mg/1. 2,4-D, elongation and division are therefore inversely related. However, by suppressing the mitogenic effect with FUdR it can be shown that cells do elongate in 1 mg/1. 2,4-D–a concentration which otherwise produces dividing, spheroidal cells. This indicates that mitogenic levels of 2,4-D do not perturb structures which support cellular elongation. This conclusion is confirmed by immuno- and electron-microscopy which show that development of elaborate arrays of cytoplasmic microtubules is unaffected by 1 mg/1. 2,4-D when FUdR is present. It is concluded that over the time periods under study here, 2,4-D regulates cell size (and shape) by stimulating growing cells to enter the division cycle and not by inhibiting elongation per se.
Comparative ultrastructure of eyespot membranes in gametes and zoospores of the green algaUlva lactuca(ulvales)
Authors: Robenek H. , Melkonian M.
Published: April 2021

Eyespot membranes in zoospores, and male and female gametes of the green alga Ulua lactuca, were studied comparatively by the freeze-fracture technique. The plasmalemma and the outer chloroplast envelope membrane overlying the eyespot lipid globules are specialized in all 3 types of reproductive cells. In the eyespot region the protoplasmic face (PF) of the outer chloroplast envelope membrane contains significantly more intramembraneous particles (IMP) compared to membrane areas outside the eyespot: in female gametes there are 2·5 times more IMP/μms, in zoospores 3 and in male gametes about 4. Small size-class IMP (4–6 nm diameter) are particularly abundant on both fracture faces of the outer chloroplast membrane, but size-class distribution is not significantly different between membrane areas inside and outside the eyespot region. The total number of IMP/eyespot on the PF of the outer chloroplast membrane was calculated to be 4 9 00 in male gametes, 5500 in female gametes and 11 2 00 in zoospores.

The results are discussed in accordance with the view that these membrane specializations participate in photoreception relating to green algal phototaxis. Evidence is presented that there is a correlation between IMP numbers per eyespot in the outer chloroplast envelope membrane and the different phototactic behaviour of gametes compared to zoospores in Ulua.
Ultrastructural changes in rat hepatocytes after partial hepatectomy, and comparison with biochemical results
Authors: Murray A. B. , Strecker W. , Silz S.
Published: April 2021

Ultrastructural changes in rat hepatocytes in the first 24 h following partial hepatectomy (p.h.), i.e. in the premitotic phase of liver regeneration, were studied using electron microscopic morphometry. Livers were investigated J, 1,4, 8, 12, 20 and 24 h after p.h. and J, 8, 20 and 24 h after a sham operation. Two effects appear to be associated specifically with the regeneration process: (1) an increase in the volume density of lysosomes to a peak between 4 and 8 h after p.h. ; and (2) a doubling in the number of mitochondria per cell by 24 h without any associated increase in the total mitochondrial volume. Two further changes were observed only after p.h.: (1) a massive accumulation of lipid in the form of lipid droplets by 24 h; and (2) the appearance of ‘protein droplets’ (very large lysosomal-like structures) at various stages. Both these changes appear to be secondary effects associated with the stimulation for, but not necessary to, cell division. The loss of glycogen observed immediately after both p.h. and a sham operation is a non-specific effect probably resulting from operation-induced stress.

The results are discussed with reference to the changes observed in the biochemical composition of blood plasma. Glucagon appears to play an important role in the stimulation of some of the ultrastructural changes observed.