Potent and Selective Covalent Inhibition of the Papain-like Protease from SARS-CoV-2

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein (ISG15) from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we have designed a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibited PLpro with kinact/KI = 10,000 M- 1 s- 1, achieved sub-μM EC50 values against three SARS-CoV-2 variants in mammalian cell lines, and did not inhibit a panel of human deubiquitinases at > 30 μM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validated our design strategy and established the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

Potent and Selective Covalent Inhibition of the Papain-like Protease from SARS-CoV-2

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein (ISG15) from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we have designed a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibited PLpro with k inact /K I = 10,000 M - 1 s - 1 , achieved sub-µM EC 50 values against three SARS-CoV-2 variants in mammalian cell lines, and did not inhibit a panel of human deubiquitinases at > 30 µM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validated our design strategy and established the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

Extradural spinal hydatid cyst causing hindlimb ataxia in a horse

INTRODUCTION

This case report describes a 13-year-old cob-cross gelding presented for evaluation of recent onset hindlimb ataxia. The gelding had undergone general anaesthesia and tenoscopy of the right hindlimb digital flexor tendon sheath at a nearby clinic three months earlier and had appeared normal at routine post-operative assessments until the sudden onset of neurological deficits. Spinal trauma was suspected initially but radiography and scintigraphy were unremarkable. Due to the severity and progressive nature of the clinical signs the -gelding was subjected to euthanasia. Post mortem examinations (computed tomography, dissection and histopathology) revealed spinal cord compression caused by a single extradural hydatid cyst (Echinococcus equinus), confirmed with PCR, at the level of the 15th thoracic vertebra. This is the first report of a spinal hydatid cyst causing hindlimb ataxia and should therefore be considered a potential differential diagnosis for ataxia in the equine patient.

Severe Cushing's syndrome due to small cell prostate carcinoma: a case and review of literature

Cushing's syndrome (CS) due to ectopic adrenocorticotrophic hormone (ACTH) is associated with a variety of tumours most of which arise in the thorax or abdomen. Prostate carcinoma is a rare but important cause of rapidly progressive CS. To report a case of severe CS due to ACTH production from prostate neuroendocrine carcinoma and summarise previous published cases. A 71-year-old male presented with profound hypokalaemia, oedema and new onset hypertension. The patient reported two weeks of weight gain, muscle weakness, labile mood and insomnia. CS due to ectopic ACTH production was confirmed with failure to suppress cortisol levels following low- and high-dose dexamethasone suppression tests in the presence of a markedly elevated ACTH and a normal pituitary MRI. Computed tomography demonstrated an enlarged prostate with features of malignancy, confirmed by MRI. Subsequent prostatic biopsy confirmed neuroendocrine carcinoma of small cell type and conventional adenocarcinoma of the prostate. Adrenal steroidogenesis blockade was commenced using ketoconazole and metyrapone. Complete biochemical control of CS and evidence of disease regression on imaging occurred after four cycles of chemotherapy with carboplatin and etoposide. By the sixth cycle, the patient demonstrated radiological progression followed by recurrence of CS and died nine months after initial presentation. Prostate neuroendocrine carcinoma is a rare cause of CS that can be rapidly fatal, and early aggressive treatment of the CS is important. In CS where the cause of EAS is unable to be identified, a pelvic source should be considered and imaging of the pelvis carefully reviewed.

Open Air Laboratories (OPAL): a community-driven research programme

OPAL is an English national programme that takes scientists into the community to investigate environmental issues. Biological monitoring plays a pivotal role covering topics of: i) soil and earthworms; ii) air, lichens and tar spot on sycamore; iii) water and aquatic invertebrates; iv) biodiversity and hedgerows; v) climate, clouds and thermal comfort. Each survey has been developed by an inter-disciplinary team and tested by voluntary, statutory and community sectors. Data are submitted via the web and instantly mapped. Preliminary results are presented, together with a discussion on data quality and uncertainty. Communities also investigate local pollution issues, ranging from nitrogen deposition on heathlands to traffic emissions on roadside vegetation. Over 200,000 people have participated so far, including over 1000 schools and 1000 voluntary groups. Benefits include a substantial, growing database on biodiversity and habitat condition, much from previously unsampled sites particularly in urban areas, and a more engaged public.

Variation in bone mineral density by anatomical site in patients with proximal humeral fractures

Low-energy fractures of the proximal humerus indicate osteoporosis and it is important to direct treatment to this group of patients who are at high risk of further fracture. Data were prospectively collected from 79 patients (11 men, 68 women) with a mean age of 69 years (55 to 86) with fractures of the proximal humerus in order to determine if current guidelines on the measurement of the bone mineral density at the hip and lumbar spine were adequate to stratify the risk and to guide the treatment of osteoporosis. Bone mineral density measurements were made by dual-energy x-ray absorptiometry at the proximal femur, lumbar spine (L2-4) and contralateral distal radius, and the T-scores were generated for comparison. Data were also collected on the use of steroids, smoking, the use of alcohol, hand dominance and comorbidity.

The mean T-score for the distal radius was −2.97 (sd 1.56) compared with −1.61 (sd 1.62) for the lumbar spine and −1.78 (sd 1.33) for the femur. There was a significant difference between the mean lumbar and radial T scores (1.36 (1.03 to 1.68); p < 0.001) and between the mean femoral and radial T-scores (1.18 (0.92 to 1.44); p < 0.001). The inclusion of all three sites in the determination of the T-score increased the sensitivity to 66% compared with that of 46% when only the proximal femur and lumbar spine were used. This difference between measurements in the upper limb compared with the axial skeleton and lower limb suggests that basing risk assessment and treatment on only the bone mineral density taken at the hip or lumbar spine may misrepresent the extent of osteoporosis in the upper limb and the subsequent risk of fracture at this site.

The assessment of osteoporosis must include measurement of the bone mineral density at the distal radius to avoid underestimation of osteoporosis in the upper limb.

Colorectal cancer survival following adjuvant chemotherapy with weekly i.v. fluorouracil 425 mg/m2 and folinic acid 50mg

e15089

Background: Adjuvant chemotherapy for colorectal cancer (CRC) using fluorouracil (5FU) and folinic acid (FA) has been proven effective and the QUASAR trial showed that a weekly administration schedule was as effective as, and less toxic than, the same daily doses delivered over 5 days every 4 weeks (the “Mayo regimen”). However the 5FU dose used (370 mg/m2) was lower than in some trials and a higher 5FU dose was considered desirable if tolerated. We therefore implemented a weekly regimen using 5FU 425 mg/m2 and DL-folinic acid 50mg in 2001 and retrospectively evaluated its efficacy and tolerability. Methods: Patients with non-metastatic CRC at assessment by medical oncologists in this institution between 2001 and 2004 were included in the analysis. Data was gathered on patient characteristics, duration of adjuvant chemotherapy and survival. Actuarial survival was calculated using the Kaplan-Meier method. Results: 417 patients (pts) were seen: 181 females, 236 males; median age 67 yrs (24–89); 291 with colon cancer, 126 with rectal cancer; 1 stage 1; 100 stage 2, 316 stage 3. Median follow-up was 6.2 years. 210 pts with colon cancer received adjuvant weekly 5FU/FA (32 stage 2, 178 stage 3) as did 58 pts with rectal cancer (50 of whom also received concurrent chemoradiation). 75% of pts with colon cancer received all 30 planned doses and 59% of rectal cancer pts received all 20 planned doses. 3 year survival for all pts treated with this regimen was 83.0% and for the subgroups with colon and rectal cancer it was 82.4% and 84.5% respectively. For stage 2 and 3 colon cancer pts treated with this regimen 3 year survival was 87.9% and 76.0% respectively; for stage III rectal cancer pts it was 84.1%. Conclusions: These outcomes compare favorably on indirect comparison with results from the QUASAR trial (which reported 3 year survival of 70.6%) and suggest that using a higher 5FU dose in this regimen is tolerable and may be advantageous.

No significant financial relationships to disclose.

Standards for the assay of Creutzfeldt-Jakob disease specimens

Assays for the agent of Creutzfeldt-Jakob disease (CJD) include measurement of infectivity in different animal systems, such as wild-type or transgenic mice, and detection of PrP(Sc) by different methods and formats. The various assays could be best calibrated against each other by use of uniform readily available materials, and samples of four human brains, two from sporadic CJD patients, one from a variant CJD patient and one from a non-CJD patient, have been prepared as 10% homogenates dispensed in 2000 vials each for this purpose. Results of in vitro methods, particularly immunoblot assays, were compared in the first collaborative study described here. While dilution end-points varied, the minimum detectable volume was surprisingly uniform for most assays and differences in technical procedure, other than the sample volume tested, had no detectable systematic effect. The two specimens from sporadic CJD cases contained both type 1 and type 2 prion proteins in approximately equal proportions. The materials have been given the status of reference reagents by the World Health Organization and are available for further study and assessment of other in vitro or in vivo assay procedures.

Localized changes in the gp120 envelope glycoprotein confer resistance to human immunodeficiency virus entry inhibitors BMS-806 and #155

BMS-806 and the related compound, #155, are novel inhibitors of human immunodeficiency virus type 1 (HIV-1) entry that bind the gp120 exterior envelope glycoprotein. BMS-806 and #155 block conformational changes in the HIV-1 envelope glycoproteins that are induced by binding to the host cell receptor, CD4. We tested a panel of HIV-1 envelope glycoprotein mutants and identified several that were resistant to the antiviral effects of BMS-806 and #155. In the CD4-bound conformation of gp120, the amino acid residues implicated in BMS-806 and #155 resistance line the "phenylalanine 43 cavity" and a water-filled channel that extends from this cavity to the inner domain. Structural considerations suggest a model in which BMS-806 and #155 bind gp120 prior to receptor binding and, upon CD4 binding, are accommodated in the Phe-43 cavity and adjacent channel. The integrity of the nearby V1/V2 variable loops and N-linked carbohydrates on the V1/V2 stem indirectly influences sensitivity to the drugs. A putative binding site for BMS-806 and #155 between the gp120 receptor-binding regions and the inner domain, which is thought to interact with the gp41 transmembrane envelope glycoprotein, helps to explain the mode of action of these drugs.

Neuronal and astrocytic responses involving the serotonergic system in human spongiform encephalopathies

The relationships between the degree of cortical prion protein (PrP) deposition, tissue vacuolation and astrocytosis were studied in the frontal cortex of 27 cases of human spongiform encephalopathy, encompassing 13 cases of sporadic Creutzfeldt-Jakob disease (sCJD), four cases of familial CJD (fCJD) (one owing to E200K mutation, one owing to 144 bp insertion, one owing to P102L mutation and one owing to A117V mutation), five cases of iatrogenic CJD (iCJD) owing to growth hormone therapy and five cases of variant CJD (vCJD). The size and number of tryptophan hydroxylase (TPH) positive cells in the dorsal raphe were determined as an index of the function of the brain's serotonergic system. The amount of PrP deposited in frontal cortex in vCJD was significantly greater than that in both sCJD and iCJD, which did not differ significantly from each other. The extent of grey matter deposition of PrP correlated with that of white matter deposition. Deposition of PrP as plaques was greater in cases of sCJD bearing valine at codon 129 of PrP gene, especially when homozygous. However, all cases of vCJD displayed florid plaque formation yet these were homozygous for methionine at codon 129. Prion protein deposition as plaques was greater in cases of sCJD with 2A PrP isotype than those with 1 PrP isotype, similar to that seen in cases of vCJD all of which are 2B PrP isotype. There were no significant differences in the extent of astrocytosis between the different aetiological groups, in either grey or white matter, as visualized with glial fibrillary acidic protein (GFAP) or 5HT-2A receptor (5HT-2AR) immunostaining, although there was a strong correlation between the severity of 5HT-2AR and GFAP reactions within both grey and white matter. The extent of PrP deposition within the grey, but not white, matter correlated with the degree of astrocytosis for both GFAP and 5HT-2AR and the extent of tissue vacuolation in grey and white matter, although the latter did not correlate with degree of astrocytosis for either GFAP or 5HT-2AR. Astrocytes may be responding directly to the presence of PrP within the tissue, rather than the vacuolar damage to neurones. Although S100beta immunoreactivity was present in astrocytes in control cases, no S100beta staining was seen in astrocytes in either grey or white matter in most CJD cases. There were no differences in the number of TPH-positive cells between CJD and control cases, although the mean TPH-positive cell size was significantly greater, and cells were more intensely stained, in CJD compared to controls, suggesting a pathological overactivity of the brain's serotonergic system in CJD. This may result in excessive release of 5HT within the brain triggering increased 5HT-2AR expression within activated astrocytes leading to release and depletion of S100beta protein from such cells. The clinical symptoms of fluctuating attention and arousal could be mediated, at least in part, by such alterations in function of the serotonergic system.

Silicone septal button in the management of a large tracheo-oesophageal fistula following primary puncture in a laryngectomee

We describe the use of a silicone septal button in the management of a patient who developed a large tracheo-oesophageal fistula following primary puncture as part of a total laryngectomy. The button was easily inserted, well tolerated and prevented leakage of solids into the trachea, allowing the patient to eat.

Refined structures of beta-ketoacyl-acyl carrier protein synthase III

beta-Ketoacyl-acyl carrier protein synthase III (FabH) is a condensing enzyme that plays central roles in fatty acid biosynthesis. Three-dimensional structures of E. coli FabH in the presence and absence of ligands have been refined to 1.46 A resolution. The structures of improved accuracy revealed detailed interactions involved in ligand binding. These structures also provided new insights into the FabH mechanism, e.g. the possible role of a water or hydroxyl anion in Cys112 deprotonation. A structure of the apo enzyme uncovered large conformational changes in the active site, exemplified by the disordering of four essential loops (84-86, 146-152, 185-217 and 305-307) and the movement of catalytic residues (Cys112 and His244). The disordering of the loops leads to greater than 50 % reduction in the FabH dimer interface, suggesting a dynamic nature for an unusually large portion of the dimer interface. The existence of a large solvent-accessible channel in the dimer interface as well as two cis-peptides (cis-Pro88 and cis-Phe308) in two of the disordered loops may explain the observed structural instabilities.

The effect of human lactoferrin on the MICs of doxycycline and rifampicin for Burkholderia cepacia and Pseudomonas aeruginosa strains

The presence of lactoferrin at the concentration found in cystic fibrosis (CF) sputum (0.9 g/L) reduced MICs and MBCs of doxycycline for Burkholderia cepacia and Pseudomonas aeruginosa strains. MICs for B. cepacia fell by 32- to 64-fold, from highly resistant to clinically achievable values. Rifampicin MICs for B. cepacia strains were reduced by lactoferrin and for some strains MBCs were reduced. These findings suggest new therapeutic approaches to infections and question the relevance of standard sensitivity tests for CF pathogens. Addition of lactoferrin to media for the routine sensitivity testing of CF isolates might give more relevant results.

Application of magnetic field-induced heat shock protein 70 for presurgical cytoprotection

To develop an alternative to hyperthermia for the induction of hsp70 for presurgical cytoprotection, we investigated the optimal exposure conditions for magnetic field induction of hsp70. Normal human breast cells (HTB124) were exposed to 60-Hz magnetic fields and hsp70 levels were measured following three different exposure conditions: continuous exposure up to 3 h, a single 20-min exposure, and a single 20-min exposure followed by repeated 20-min exposures at different field strengths. In cells exposed continuously for 3 h, hsp70 levels peaked (46%) within 20 min and returned to control levels by 2 h. Following a single 20-min exposure, the return of hsp70 levels to control values extended to more than 3 h. When cells underwent a 20-min exposure followed by repeated 20-min exposures (restimulation) with different field strengths, additional increases in hsp70 levels were induced: 31% at 1 h, 41% at 2 h, and 30% at 3 h.

Magnetic field activation of protein-DNA binding

The mechanisms involved in sensing, signaling, and coordinating changes resulting from magnetic field-induced stress show substantial similarities to those of heat shock, e.g., magnetic field-induced heat shock 70 gene (HSP70) expression involves heat shock factor (HSF) activation and heat shock element binding. However, an additional requirement for transactivation of HSP70 expression by magnetic fields is the binding of Myc protein, indicating that additional elements and/or pathways are involved in the induction of HSP70 expression by magnetic fields. To investigate the possible participation of additional genetic elements in magnetic field-induced HSP70 expression, we examined both magnetic field exposure and heat shock on protein-DNA binding of the transcription factors HSF, AP-1, AP-2, and SP-1 in four human cell lines. The binding sites for these transcription factors are present in the HSP70 promoter. AP-1 binding activity, normally not increased by heat shock, was increased by magnetic fields; heat shock induced an increase only in HSF binding. Although intersecting and converging signaling pathways could account for the multiplicity of elements involved in magnetic field-induced HSP70 transcription, direct interaction of magnetic fields with DNA is also a possible mechanism. Because magnetic fields penetrate the cell, they could well react with conducting electrons present in the stacked bases of the DNA.

Myc-mediated transactivation of HSP70 expression following exposure to magnetic fields

We investigated c-myc protein-binding sites on the HSP70 promoter as modulators of the induction of HSP70 gene expression in response to magnetic field stimulation (8microT at 60Hz) and whether the presence of c-myc protein potentiates transactivation of HSP70 expression. A 320 base pair region in the HSP70 promoter (+1 to -320) was analyzed. This region contains two c-myc-protein binding sites with consensus sequences located at -230 and -160 nucleotide positions (relative to the transcription initiation site) and overlapping with the region reported for the regulation of HSP70 gene expression by c-myc protein. This promoter region is upstream of other regulatory sequences, including the heat shock element (HSE), AP-2, and serum response element (SRE). Transfectants containing both c-myc protein-binding sites, HSP-MYC A and HSP-MYC B, and exposed to magnetic fields showed a 3.0-fold increase in expression of CAT activity as compared with sham-exposed control transfectants. Transfectants containing one c-myc binding site, HSP-MYC A, and exposed to magnetic fields showed a 2.3-fold increase in CAT expression. Transfectants in which both HSP-MYC A and HSP-MYC B binding sites were deleted showed no magnetic field sensitivity; values were virtually identical with sham-exposed controls. If the c-myc expression vector was not co-transfected with the constructs containing myc-binding sites, there was no difference in the expression of CAT activity between magnetically stimulated and sham-exposed controls, although both responded to heat shock. These data suggest that endogenous elevated levels of myc protein contribute to the induction of HSP70 in response to magnetic field stimulation.

Electromagnetic field exposure induces rapid, transitory heat shock factor activation in human cells

Stimulation of human promyelocytic HL60 cells by a 60Hz magnetic field at normal growth temperatures results in heat shock factor 1 activation and heat shock element binding, a sequence of events that mediates the stress-induced transcription of the stress gene HSP70 and increased synthesis of the stress response protein hsp70kD. Thus, the events mediating the electromagnetic field-stimulated stress response appear to be similar to those reported for other physiological stresses (e.g., hyperthermia, heavy metals, oxidative stress) and could well be the general mechanism of interaction of electromagnetic fields with cells.

A two-year follow-up on the effects of a smoking ban in an inpatient psychiatric service

The effects of prohibiting cigarette smoking on the behavior of patients on a 25-bed psychiatric inpatient unit were assessed immediately after implementation of a smoking ban and two years later. No major behavioral disruptions were observed after the ban. The number of calls for security assistance, physical assaults, instances of leather restraints and of seclusions, and discharges against medical advice did not increase significantly immediately after the restriction on smoking or two years later. Significantly more verbal assaults and prescribing of p.r.n. medications for anxiety occurred immediately after the ban but not two years later.

Mechanism and computer simulation of immune complex formation, opsonization, and clearance

A computer simulation of immune complex formation, opsonization, and clearance has been developed (ICMODEL) that uses equations describing the kinetics of known immunologic processes and an additional pathologic process of immune complex-mediated tissue damage and antigen production. ICMODEL was used to (1) compare simulated with reported immune response kinetics, (2) evaluate the relative stability of the immune system described by the simulation, and (3) determine the conditions required to produce high immune complex levels as found in patients with immune complex-mediated disease. ICMODEL simulated primary and secondary immune responses as well as short- and long-term immunity. ICMODEL also depicted a relatively stable immune response system. Under certain conditions, however, the system could be perturbed, resulting in an unstable response. For example, when the rate constant regulating Fc gamma-mediated phagocytosis was decreased and the rate constant regulating immune complex-mediated tissue damage/antigen production was increased, immune complex concentrations oscillated with time and increased exponentially. These data suggest that ICMODEL can be used to define the specific parameters that, when perturbed, will give rise to increased immune complex concentrations. As such, this model has direct implications for studies of immune complex-mediated disease in human patients.

Use of species-specific oligonucleotide probes to detect Mycoplasma gallisepticum, M. synoviae, and M. iowae PCR amplification products

Three digoxigenin-labeled oligonucleotide probes, complementary to the variable region of the 16S ribosomal RNA (rRNA) gene of Mycoplasma gallisepticum, M. synoviae, and M. iowae were designed. The oligonucleotides were used in a dot blot hybridization assay. The target DNA is a 780-bp fragment of the 16S rRNA gene of avian mycoplasmas amplified by a single set of primers (multispecies polymerase chain reaction [PCR]). The oligonucleotide probes were specific for their corresponding PCR products at hybridization conditions of 56 C and 50% formamide. The detection limit of the dot blot hybridization assay was approximately 70, 50, and 30 colony-forming units for M. gallisepticum, M. synoviae, and M. iowae, respectively, per 4 microliters of PCR. In general, the oligonucleotide probe dot blotting assay was a more sensitive and effective method of detecting PCR products than detection by gel electrophoresis.

Unsuspected subdural hematoma as a differential diagnosis in elderly patients

Subdural hematomas are among the most common forms of intracranial hemorrhage encountered in clinical practice and are a surgically remediable cause of dementia. When the symptom presentation is subtle or diffuse, a subdural hematoma can be overlooked. This is especially true among elderly people who may exhibit unrelated, preexisting dementia or delirium. Particularly confusing is that such declines in intellectual capacity can also result from subdural hematoma. It is therefore essential that a thorough physical and neurologic assessment be done on all patients with cognitive deficiencies. This always includes brain imaging. Early recognition of a subdural hematoma is important, given its treatability and potential reversibility. We describe an elderly woman with new-onset cognitive deficit and gait dyspraxia. There was no evidence of trauma. Physical examination was otherwise unremarkable. Initially, she refused evaluation, but once a subdural hematoma was identified by a tomographic scan, a satisfactory outcome followed surgical intervention.

Effects of age and genetic growth rate on the crystallin composition of the chick lens

This two part study continues and extends our examination of the effects of age and of genetically determined intrinsic growth rate on the overall protein composition of chick lens epithelia, lens fiber masses and whole lenses. Water-soluble proteins were analyzed by SDS-polyacrylamide and 2-dimensional gel electrophoresis. First, detailed age-related changes in protein expression between day 4 of embryonic development and the 8-week adult stage are described for one normal chick strain. Secondly, comparisons are made between day-old post-hatch chicks of four different genotypes: two genetically unrelated chick strains with a high growth rate and propensity for hyperplasia of the lens epithelium and two unrelated slow-growing strains, both with normal lens morphology. We find that the beta/delta-crystallin ratio in lens epithelia and fiber masses is higher in both the slow- than in both the fast-growing strains. The data emphasizes the importance of quantitative and non-coordinate changes in crystallin polypeptide expression during lens growth and development, and implicates growth rate as a modifier of the pattern of crystallin expression.

Mannitol injections: with or without filter needles? A cost-effectiveness analysis

A clinical economic evaluation was conducted to assess the cost-effectiveness of filtration of i.v. mannitol injections. Clinical decision analysis was used to model the costs and benefits of using filter needles for undiluted, i.v. push injections of mannitol 25%. Sensitivity analysis conducted by varying all uncertain variables to test best and worst case scenarios revealed that the use of filter needles is a cost-effective measure in all relevant scenarios.

Purification of a novel glycosylated ferritin from horse heart

We have previously shown that mRNA coding for ferritin L subunit is present on both cytosolic ribosomes and endoplasmic reticulum-bound ribosomes in rat heart tissue [Campbell et al. (1989) Arch Biochem Biophys 273:89-98]; from this we infer that heart tissue is capable of making a secreted ferritin. We now report the purification from horse heart, of a ferritin that specifically binds to Concanavalin A-Sepharose and is immunologically cross-reactive with antibodies raised against both horse cellular ferritin and horse serum ferritin. Where cellular ferritin is 10 nm in diameter and contains primarily 21-kDa subunits (as determined by gel exclusion chromatography and electron microscopy), the glycosylated heart ferritin is smaller with diameters of 3-5 nm. Antisera raised against serum ferritin cross-reacted with the glycosylated heart ferritin did but did not show significant cross-reactivity with cellular ferritin thus indicating that serum ferritin and glycosylated heart ferritin have antigenic determinants which may not be present on cellular ferritin. The glycosylated ferritin also differs from cellular ferritin in subunit composition, with subunits of 66, 60.5, 53.5, 43.5, and 29.5 kDa, as shown by SDS-PAGE and Western blot analysis. Interestingly, ferritin purified from horse serum contains subunits of similar size.

The majority of independently transformed BHK cell clones share a single functional lesion which determines anchorage independence and influences tumorigenicity

Expression of the anchorage-independent transformed phenotype in BHK 21/13 cells generally behaves as a recessive trait. When chemically induced and spontaneously arising transformants are fused to the nontransformed parent line, transformation is initially suppressed, reappearing after extended growth of the hybrids. In this paper, complementation for the expression of anchorage independence was sought among a large group of such transformants, all independently derived from BHK 21/13 cells. Tumorigenicity studies on selected hybrids and parental lines indicated that the in vitro trait of anchorage independence is an accurate indicator of in vivo neoplasia for these cells. Seventeen of the 18 clones tested did not complement one or more of three tester strains. This result indicates that anchorage independence arose in these clones as a result of lesions in the same genetic function and suggests that the final step in the progressive changes of carcinogenesis may frequently be restricted to lesions at a single locus.

The effect of antiserum quality on strain specificity assessment of foot and mouth disease virus by the neutralization reaction

The factors affecting the virus strain specificity of antibody to foot an mouth disease virus prepared by a variety of protocols in several species were evaluated by neutralization tests. The time at which the serum was taken, the antigen dose given, whether or not revaccination had occurred and the animal species in which the sera were prepared, did not appear to affect the strain specificity of serum prepared to inactivated antigens when measured in neutralization tests, probably because of the restricted nature of the antigenic site involved. However, variation was observed with convalescent animal sera or sera from animals which had received trypsin cleaved virus were used. For these reasons banks of reference antisera are prepared as pooled sera using one or two inoculations of inactivated antigen.

Evaluation of the antigenic variation within type-A foot and mouth disease virus isolates from Asia

The serological interrelationships among 17 type A FMD virus strains from eight Asian countries were studied by the two-dimensional microneutralization test. Complex direct and indirect relationships were observed. Overall, however, the virus strains studied could be classified as belonging to the A22 group on the basis of r value differentiation at P less than 0.01.

Demonstration of neutralizing and non-neutralizing epitopes on the trypsin-sensitive site of foot-and-mouth disease virus

The isolation of monoclonal antibodies directed against the trypsin-sensitive site on the 140S particle of foot-and-mouth disease virus (FMDV) has enabled the demonstration of at least three distinct epitopes within this site. Reaction with two of these resulted in neutralization of virus infectivity. None of the epitopes appeared to be present on the 12S particles, and one of the neutralizing epitopes was sensitive to even milder configurational changes of the particle.

Computerization of foot and mouth disease virus strain relationship data

Since 1976 the two dimensional microneutralization test has been adopted in our laboratory as the reference test for foot and mouth disease virus (FMDV) strain differentiation. Large numbers of homologous-heterologous comparisons have been performed and manual storage and retrieval of the data had become cumbersome. The objective of computerization was to provide a databank with fast easy access to enable accurate statistical calculations to be performed on the raw data entries and to simplify the evaluation of statistical and biological significance. The computer system is written in Fortran for an IBM 4341 computer running under the VM/CMS operating system.

A serological evaluation of 1979-1982 Kenyan foot-and-mouth disease type SAT 2 viruses

Serological evaluations of foot-and-mouth disease type SAT 2 viruses isolated in Kenya between 1979 and 1982 were performed using the two-dimensional microneutralization test. Nine field isolates of epizootiological significance were compared with four vaccine viruses. The results obtained identified Tan 5/68 as the most appropriate reference vaccine virus strain since it had the broadest serological spectrum. Potent Tan 5/68 vaccines would be expected to provide adequate protection against the contemporary SAT 2 field viruses. In the case of K183/74, which also was shown to have a broad spectrum with viruses isolated in Kenya, the results show that the 1982 isolate from central Kenya was significantly divergent (r less than 1.00 at P = 0.01) and warranted tactical revaccination for its control. The study highlighted the fact that strain R1215 which had been isolated from the oesophageal-pharyngeal swabs of asymptomatic carrier cattle had a narrow serological spectrum suggesting that such viruses could be unsuitable as vaccine for the national campaign.

Detection by mass spectrometry of hydrocarbon biradicals, pyridine and aniline in a flame ionization detector

The mass spectra of ions of > 75 in an f.i.d.-type flame with benzene additive have shown that hitherto undetected species of formulas CllH9+ and CI3H9+ are present, which may be attributed to protonation of the biradicals C11H8 and C13H8 by H3O+. The remainder of the hydrocarbon ions present are attributable to protonation of aromatic compounds (e.g. naphthalene and indene) which have been detected previously in premixed benzeneloxygen flames by electron impact ionization. Addition of NH3 to the benzene sample suppresses all the hydrocarbon peaks of m/z > 100 but generates new peaks of m/z 80 and 94, attributable to the protonation of pyridine and aniline. Aniline may be generated by addition of NH2 radicals to benzene in the pyrolysis and reaction zones of the flame.

Effect of acute ureteral obstruction on terminal collecting duct function in the weanling rat

Micropuncture techniques were employed to evaluate the effects of unilateral ureteral obstruction (UUO) of 18 h duration on the function of the terminal collecting duct in weanling rats 90-120 min following release of obstruction. In control animals and after release of UUO, water and sodium reabsorption continued along the terminal segment of the collecting duct. Fractional delivery of water (FRH2O) and sodium (FRNa) to this segment was increased after release of UUO. A significantly greater amount of the FRH2O and FRNa was reabsorbed along the terminal collecting duct following release of obstruction than in controls. Potassium was not consistently reabsorbed or secreted in either group. Following release of UUO, the osmolality of collecting duct fluid was lower than in controls, but was not different from the osmolality of fluid obtained from the bend of the loop of Henle. The results suggest that the permeability to water and the reabsorptive capacity of the collecting duct are not altered by acute obstruction.

Deep nephron function after release of acute unilateral ureteral obstruction in the young rat

The effects of acute unilateral ureteral obstruction (UUO) of 18 h duration on deep nephron function was evaluated in 14 weanling rats with the technique of micropuncture. After release of UUO, 3.4 +/- 0.66% (SE) of the filtered water remained at the tip of the collecting duct nearly fivefold greater than in controls (0.75 +/- 0.10%). Similar differences were seen in fractional sodium that remained at this site. The ratio of tubular fluid osmolality to that of plasma was also reduced in the UUO group (1.53 +/- 0.06 vs. 4.60 +/- 0.26 in controls, P less than 0.001). Single nephron glomerular filtration rate of cortical and deep nephrons was significantly less (P less than 0.001) after release of UUO. Although the percentage of filtering nephrons was significantly reduced in both nephron populations, the decline in glomerular filtration rate was greater in cortical than in juxtamedullary nephrons (cortical:juxtamedullary nephrons = 27.6 +/- 4.5% vs. 53.3 +/- 5.2% in controls, P less than 0.005) which suggests that single nephron glomerular filtration rate is redistributed to deep nephrons after release of UUO. In contrast to cortical nephrons, the amount of tubular fluid which remains near the bend of the loop of Henle of deep nephrons was greater after release of UUO. This appeared to be the result of a decrease in the reabsorption of both water (tubular fluid:plasma inulin = 2.41 +/- 0.16 vs. 7.94 +/- 0.69 in controls, P less than 0.001) and sodium (52.3 +/- 4% vs. 40.7 +/- 2.9% of the filtered sodium in controls, P less than 0.02). It is suggested that this altered reabsorption occurs along both the proximal tubule and descending limb of the loop of Henle of juxtamedullary nephrons. Inner medullary plasma flow (IMPF), as measured with the [125I]albumin-accumulation technique, was significantly depressed before release of UUO, but exceeded control values 90 min postrelease. Such changes imply that the filtration fraction of deep nephrons is decreased and that physical factors in the proximal tubular reabsorption of sodium have been altered. When papillary solute content was measured before release of UUO it was low (428 +/- 23 vs. 1,205 +/- 106 mosmol/kg in controls, P less than 0.001) which indicates that the decline in papillary osmolality is not a consequence of the increased IMPF seen after ureteral release, but rather precedes it. In fact, the decline in papillary osmolality may contribute to the increase in IMPF after release of UUO and to the decreased reabsorption of fluid along the descending limb of the loop of Henle.

Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains

A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.

Effects of acute bilateral ureteral obstruction on deep nephron and terminal collecting duct function in the young rat

The effects of acute bilateral ureteral obstruction (BUO) of 18-h duration on deep nephron and collecting duct function were studied by micropuncture in 11 weanling rats. After release of BUO glomerular filtration rate was reduced (178+/-15 vs. 1,343+/-119 mul/min per g kidney weight in shams), while urine flow was increased averaging 17.5+/-1.3 vs. 6.8+/-0.72 mul/min per g kidney weight in controls. There was a marked increase in the absolute and fractional excretion of Na. Single nephron glomerular filtration rate of deep nephrons was reduced in the BUO group, mean 19.4+/-3.5 vs. 77.0+/-7.7 nl/min per g kidney weight in shams. Single nephron glomerular filtration rate of superficial nephrons fell to the same extent after relief of BUO. Mean tubular fluid to plasma inulin ratio of fluid from Henle's loop was 2.46+/-0.20 after relief of BUO vs. 8.23+/-0.85 in shams. This suggested a reduction in the reabsorption of Na and water before the bend of the loop of Henle, most likely in both the proximal tubule and descending limb. Fluid osmolality was depressed due to a decline in both Na and nonelectrolyte solute content. After release of BUO the percentage of filtered water remaining in the collecting duct (CD) at the base of the papilla was greater than in controls (13.3+/-2.0 and 1.72+/-0.01%, respectively) but fell significantly by the tip of the papilla to 7.92+/-1.12 vs. 1.17+/-0.02% in controls. These results indicate that water was reabsorbed along the terminal CD after relief of ureteral obstruction. In fact, a greater fraction was reabsorbed in this segment after release of BUO (5.37+/-1.58%) than after sham operation (0.55+/-0.15%). Similar changes were seen in Na excretion. Thus alterations in deep nephron function appear to contribute to the natriuresis and diuresis which follow release of BUO while terminal CD function in this model appears intact.