Single-molecule FRET unmasks structural subpopulations and crucial molecular events during FUS low-complexity domain phase separation

Biomolecular condensates formed via phase separation of proteins and nucleic acids are thought to be associated with a wide range of cellular functions and dysfunctions. We dissect critical molecular events associated with phase separation of an intrinsically disordered prion-like low-complexity domain of Fused in Sarcoma by performing single-molecule studies permitting us to access the wealth of molecular information that is skewed in conventional ensemble experiments. Our single-molecule FRET experiments reveal the coexistence of two conformationally distinct subpopulations in the monomeric form. Single-droplet single-molecule FRET studies coupled with fluorescence correlation spectroscopy, picosecond time-resolved fluorescence anisotropy, and vibrational Raman spectroscopy indicate that structural unwinding switches intramolecular interactions into intermolecular contacts allowing the formation of a dynamic network within condensates. A disease-related mutation introduces enhanced structural plasticity engendering greater interchain interactions that can accelerate pathological aggregation. Our findings provide key mechanistic underpinnings of sequence-encoded dynamically-controlled structural unzipping resulting in biological phase separation.

Hydrogen-Deuterium Exchange Vibrational Raman Spectroscopy Distinguishes Distinct Amyloid Polymorphs Comprising Altered Core Architecture

Amyloid fibrils are ordered protein aggregates comprising a hydrogen-bonded central cross-β core displaying a structural diversity in their supramolecular packing arrangements within the core. Such an altered packing results in amyloid polymorphism that gives rise to morphological and biological strain diversities. Here, we show that vibrational Raman spectroscopy coupled with hydrogen/deuterium (H/D) exchange discerns the key structural features that are responsible for yielding diverse amyloid polymorphs. Such a noninvasive and label-free methodology allows us to structurally distinguish distinct amyloid polymorphs displaying altered hydrogen bonding and supramolecular packing within the cross-β structural motif. By using quantitative molecular fingerprinting and multivariate statistical analysis, we analyze key Raman bands for the protein backbone and side chains that allow us to capture the conformational heterogeneity and structural distributions within distinct amyloid polymorphs. Our results delineate the key molecular factors governing the structural diversity in amyloid polymorphs and can potentially simplify studying amyloid remodeling by small molecules.

ATP modulates self-perpetuating conformational conversion generating structurally distinct yeast prion amyloids that limit autocatalytic amplification

Prion-like self-perpetuating conformational conversion of proteins into amyloid aggregates is associated with both transmissible neurodegenerative diseases and non-Mendelian inheritance. The cellular energy currency ATP is known to indirectly regulate the formation, dissolution, or transmission of amyloid-like aggregates by providing energy to the molecular chaperones that maintain protein homeostasis. In this work, we demonstrate that ATP molecules, independent of any chaperones, modulate the formation and dissolution of amyloids from a yeast prion domain (NM domain of Saccharomyces cerevisiae Sup35) and restricts autocatalytic amplification by controlling the amount of fragmentable and seeding-competent aggregates. ATP, at (high) physiological concentrations in the presence of Mg²⁺, kinetically accelerates NM aggregation. Interestingly, ATP also promotes phase-separation-mediated aggregation of a human protein harboring a yeast prion-like domain. We also show that ATP disaggregates preformed NM fibrils in a dose-independent manner. Our results indicate that ATP-mediated disaggregation, unlike the disaggregation by the disaggregase Hsp104, yields no oligomers that are considered one of the critical species for amyloid transmission. Furthermore, high concentrations of ATP delimited the number of seeds by giving rise to compact, ATP-bound NM fibrils that exhibited nominal fragmentation by either free ATP or Hsp104 disaggregase to generate lower molecular weight amyloids. Additionally, (low) pathologically relevant ATP concentrations restricted autocatalytic amplification by forming structurally distinct amyloids which are found seeding-inefficient due to their reduced β-content. Our results provide key mechanistic underpinnings of concentration-dependent chemical chaperoning by ATP against prion-like transmissions of amyloids.

Single-droplet surface-enhanced Raman scattering decodes the molecular determinants of liquid-liquid phase separation

Biomolecular condensates formed via liquid-liquid phase separation (LLPS) are involved in a myriad of critical cellular functions and debilitating neurodegenerative diseases. Elucidating the role of intrinsic disorder and conformational heterogeneity of intrinsically disordered proteins/regions (IDPs/IDRs) in these phase-separated membrane-less organelles is crucial to understanding the mechanism of formation and regulation of biomolecular condensates. Here we introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that utilizes surface-engineered, plasmonic, metal nanoparticles to unveil the inner workings of mesoscopic liquid droplets of Fused in Sarcoma (FUS) in the absence and presence of RNA. These highly sensitive measurements offer unprecedented sensitivity to capture the crucial interactions, conformational heterogeneity, and structural distributions within the condensed phase in a droplet-by-droplet manner. Such an ultra-sensitive single-droplet vibrational methodology can serve as a potent tool to decipher the key molecular drivers of biological phase transitions of a wide range of biomolecular condensates involved in physiology and disease.

The authors introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that illuminates a wealth of molecular information within the mesoscopic liquid condensed phase of Fused in Sarcoma in the absence and presence of RNA.

An intrinsically disordered pathological prion variant Y145Stop converts into self-seeding amyloids via liquid-liquid phase separation

Biomolecular condensation via liquid-liquid phase separation of intrinsically disordered proteins/regions (IDPs/IDRs) along with other biomolecules is proposed to control critical cellular functions, whereas aberrant phase transitions are associated with a range of neurodegenerative diseases. Here, we show that a disease-associated stop codon mutation of the prion protein (PrP) at tyrosine 145 (Y145Stop), resulting in a truncated, highly disordered, N-terminal IDR, spontaneously phase-separates into dynamic liquid-like droplets. Phase separation of this highly positively charged N-terminal segment is promoted by the electrostatic screening and a multitude of weak, transient, multivalent, intermolecular interactions. Single-droplet Raman measurements, in conjunction with an array of bioinformatic, spectroscopic, microscopic, and mutagenesis studies, revealed a highly mobile internal organization within the liquid-like condensates. The phase behavior of Y145Stop is modulated by RNA. Lower RNA:protein ratios promote condensation at a low micromolar protein concentration under physiological conditions. At higher concentrations of RNA, phase separation is abolished. Upon aging, these highly dynamic liquid-like droplets gradually transform into ordered, β-rich, amyloid-like aggregates. These aggregates formed via phase transitions display an autocatalytic self-templating characteristic involving the recruitment and binding-induced conformational conversion of monomeric Y145Stop into amyloid fibrils. In contrast to this intrinsically disordered truncated variant, the wild-type full-length PrP exhibits a much lower propensity for both condensation and maturation into amyloids, hinting at a possible protective role of the C-terminal domain. Such an interplay of molecular factors in modulating the protein phase behavior might have much broader implications in cell physiology and disease.

Ultrasensitive Characterization of the Prion Protein by Surface-Enhanced Raman Scattering: Selective Enhancement via Electrostatic Tethering of the Intrinsically Disordered Domain with Functionalized Silver Nanoparticles

Surface-enhanced Raman scattering (SERS) circumvents the inherent insensitivity of Raman spectroscopy and offers a powerful tool for the ultrasensitive detection and characterization of biomolecules at low concentrations. Here we show that SERS via electrostatic tethering between surface-modified negatively charged silver nanoparticles and highly positively charged intrinsically disordered N-terminal domain of the prion protein allows highly sensitive and reproducible protein detection and characterization at as low as hundreds of nanomolar protein concentrations. These measurements preferentially illuminate a selective part of the protein due to a sharp dependence of the near-field intensity on the distance between the nanoparticle surface and the protein. We also demonstrate that by shortening the length of the disordered tail it is possible to achieve a domain-selective Raman enhancement to study the C-terminal globular domain. Our tether-length-dependent SERS methodology will serve as a potent, noninvasive, and label-free strategy to detect and characterize a wide range of proteins possessing disordered segments.

Excitation Energy Migration Unveils Fuzzy Interfaces within the Amyloid Architecture

Amyloid fibrils are highly ordered nanoscopic protein aggregates comprising a cross-β amyloid core and are associated with deadly human diseases. Structural studies have revealed the supramolecular architecture of a variety of disease-associated amyloids. However, the critical role of transient intermolecular interactions between the disordered polypeptide segments of protofilaments in directing the supramolecular structure and nanoscale morphology remains elusive. Here, we present a unique case to demonstrate that interchain excitation energy migration via intermolecular homo-Förster resonance energy transfer can decipher the architecture of amyloid fibrils of human α-synuclein. Site-specific homo-Förster resonance energy transfer efficiencies measured by fluorescence depolarization allowed us to construct a two-dimensional proximity correlation map that defines the supramolecular packing of α-synuclein within the fibrils. These studies captured unique heteroterminal cross talks between the fuzzy interprotofilament interfaces of the parallel-in-register amyloid spines. Our results will find applications in discerning the broader role of protein disorder and fuzziness in steering the distinct polymorphic amyloids that exhibit strain-specific disease phenotypes.

Intrinsically disordered proteins in the formation of functional amyloids from bacteria to humans

Amyloids are nanoscopic ordered self-assemblies of misfolded proteins that are formed via aggregation of partially unfolded or intrinsically disordered proteins (IDPs) and are commonly linked to devastating human diseases. An enlarging body of recent research has demonstrated that certain amyloids can be beneficial and participate in a wide range of physiological functions from bacteria to humans. These amyloids are termed as functional amyloids. Like disease-associated amyloids, a vast majority of functional amyloids are derived from a range of IDPs or hybrid proteins containing ordered domains and intrinsically disordered regions (IDRs). In this chapter, we describe an account of recent studies on the aggregation behavior of IDPs resulting in the formation of functional amyloids in a diverse range of organisms from bacteria to human. We also discuss the strategies that are used by these organisms to regulate the spatiotemporal amyloid assembly in their physiological functions.

SlPRA1A/RAB attenuate EIX immune responses via degradation of LeEIX2 pattern recognition receptor

Pattern recognition receptors (PRR) are plasma membrane (PM) proteins that recognize microbe-associated molecular patterns (MAMPs), triggering an immune response. PRR are classified as receptor like kinases (RLKs) or receptor like proteins (RLPs). The PM localization of PRRs, which is crucial for their availability to sense MAMPs, depends on their appropriate trafficking through the endomembrane system. Recently, we have identified SlPRA1A, a prenylated RAB acceptor type-1 (PRA1) from S. lycopersicum, as a regulator of RLP-PRR localization and protein levels. SlPRA1A overexpression strongly decreases RLP-PRR protein levels, particularly those of LeEIX2, redirecting it to the vacuole for degradation. Interestingly, SlPRA1A does not affect RLK-PRRs, indicating its activity to be specific to RLP-PRR systems. As PRA1 proteins stabilize RABs on membranes, promoting RABs activity, we aimed to identify a RAB target of SlPRA1A. Screening of a set of A. thaliana RABs revealed that AtRABA1e is able to mimic SlPRA1A activity. Through live cell imaging, we observed that SlPRA1A enhances AtRABA1e localization on SlPRA1A positive punctuated structures. These results indicate that AtRABA1e is a putative target of SlPRA1, and a co-regulator of LeEIX2 trafficking and degradation.

Constitutive caspase-like machinery executes programmed cell death in plant cells

The morphological features of programmed cell death (PCD) and the molecular machinery involved in the death program in animal cells have been intensively studied. In plants, cell death has been widely observed in predictable patterns throughout differentiation processes and in defense responses. Several lines of evidence argue that plant PCD shares some characteristic features with animal PCD. However, the molecular components of the plant PCD machinery remain obscure. We have shown that plant cells undergo PCD by constitutively expressed molecular machinery upon induction with the fungal elicitor EIX or by staurosporine in the presence of cycloheximide. The permeable peptide caspase inhibitors, zVAD-fmk and zBocD-fmk, blocked PCD induced by EIX or staurosporine. Using labeled VAD-fmk, active caspase-like proteases were detected within intact cells and in cell extracts of the PCD-induced cells. These findings suggest that caspase-like proteases are responsible for the execution of PCD in plant cells.

Anal incontinence: prevalence among female patients attending a urogynecologic clinic

The present study prospectively surveyed the prevalence of anal incontinence among 283 consecutive female patients attending a urogynecologic outpatient clinic in a maternity hospital. Data concerning bowel habits, laxative use, previous anorectal surgery, and the presence, severity, and frequency of anal incontinence were collected by interviewing the patients. Anal incontinence was reported by 83 women, representing 29% of the study population. Of those reporting anal incontinence, 30% (9% of the study population) were incontinent to solid feces, 22% (6%) to liquid feces, and 48% (14%) to gas. Age distribution demonstrates progressive rise and a high prevalence of anal incontinence in patients older than 60 years. A significant higher rate of vacuum deliveries was found among patients with anal incontinence, compared with continent patients (9.6% vs. 2.5%; P = 0.01). Increased prevalence of anal incontinence was also found among patients with past history of hemorrhoidectomy and those with urodynamic diagnosis of combined genuine stress incontinence and detrusor instability/sensory urgency. In conclusion, in patients attending a urogynecologic clinic, anal incontinence is a frequent, although rarely volunteered, symptom.

A point mutation in the ethylene-inducing xylanase elicitor inhibits the beta-1-4-endoxylanase activity but not the elicitation activity

Ethylene-inducing xylanase (EIX) elicits plant defense responses in certain tobacco (Nicotiana tabacum) and tomato cultivars in addition to its xylan degradation activity. It is not clear, however, whether elicitation occurs by cell wall fragments released by the enzymatic activity or by the xylanase protein interacting directly with the plant cells. We cloned the gene encoding EIX protein and overexpressed it in insect cells. To determine the relationship between the two activities, substitution of amino acids in the xylanase active site was performed. Substitution at glutamic acid-86 or -177 with glutamine (Gln), aspartic acid (Asp), or glycine (Gly) inhibited the beta-1-4-endoxylanase activity. Mutants having Asp-86 or Gln-177 also lost the ability to induce the hypersensitive response and ethylene biosynthesis. However, mutants having Gln-86, Gly-86, Asp-177, or Gly-177 retained ability to induce ethylene biosynthesis and the hypersensitive response. Our data show that the xylanase activity of EIX elicitor can be separated from the elicitation process, as some of the mutants lack the former but retain the latter.

Isolation of a novel SUMO protein from tomato that suppresses EIX-induced cell death

Challenging tomato or tobacco varieties with ethylene-inducing xylanase (EIX) from the fungus Trichoderma viride causes rapid induction of plant defence responses leading to programmed cell death. Using the yeast two-hybrid system, we isolated a novel protein, tomato small ubiquitin-related modifier protein (T-SUMO), which specifically interacts with EIX. T-SUMO, a cytoplasmic protein, is a member of the ubiquitin-like protein family. It shows homology to human protein sentrin/SUMO1, which suppresses tumour necrosis factor-induced cell death. Transgenic plants that express T-SUMO in the sense orientation suppress EIX induction of ethylene biosynthesis and cell death, while in the antisense orientation they enhance EIX-induced ethylene biosynthesis. These results indicate that T-SUMO is involved in mediating the signal generated by EIX that leads to induction of plant defence responses.

The never ripe mutant provides evidence that tumor-induced ethylene controls the morphogenesis of agrobacterium tumefaciens-induced crown galls on tomato stems

We confirm the hypothesis that Agrobacterium tumefaciens-induced galls produce ethylene that controls vessel differentiation in the host stem of tomato (Lycopersicon esculentum Mill.). Using an ethylene-insensitive mutant, Never ripe (Nr), and its isogenic wild-type parent we show that infection by A. tumefaciens results in high rates of ethylene evolution from the developing crown galls. Ethylene evolution from isolated internodes carrying galls was up to 50-fold greater than from isolated internodes of control plants when measured 21 and 28 d after infection. Tumor-induced ethylene substantially decreased vessel diameter in the host tissues beside the tumor in wild-type stems but had a very limited effect in the Nr stems. Ethylene promoted the typical unorganized callus shape of the gall, which maximized the tumor surface in wild-type stems, whereas the galls on the Nr stems had a smooth surface. The combination of decreased vessel diameter in the host and increased tumor surface ensured water-supply priority to the growing gall over the host shoot. These results indicate that in addition to the well-defined roles of auxin and cytokinin, there is a critical role for ethylene in determining crown-gall morphogenesis.

Dynamic perspectives of paradoxical intervention

This paper describes the use of paradoxical intervention with a patient who, despite his persistent appeals for help, remained uncooperative. It endeavors to show an understanding of the patient's destructiveness as an expression of his neediness and envy, which he expresses via his repeated use of projective identification and suggests this intervention as a way out. From a dynamic perspective the paradoxical intervention encompasses two contrasting aspects: On the one hand, it rechannels the patient's destructiveness and envy in a beneficial direction. In that sense the intervention fulfills the patient's wish for an omnipotent therapist and for painless therapy, while appearing to prevent personality change. On the other hand, the intervention interferes with the continued use of projective identification, it facilitates the expression of non-destructive aggression, creates an ambiguity surrounding the question of who is in fact in control of the therapy and, finally, it possibly facilitates the creation of a potential space. In that sense the paradoxical intervention assists in achieving both the experience of separateness and the ability to use symbolization. Parallel processes are described in the therapist's countertransference.

Brush cytology and biopsy in the diagnosis of colorectal cancer. A comparison

OBJECTIVE

To determine the usefulness of brush cytology of colorectal lesions as compared to biopsy examination.

STUDY DESIGN

One hundred brushing cytologies and biopsies were performed on patients who underwent colonoscopic examination for different symptoms. The cytologic smears were classified into five cytologic diagnostic categories. The histologic diagnoses were adenocarcinoma, adenoma and nonneoplastic lesion.

RESULTS

Twenty-six cases were cytologically positive for malignant cells, and all were histologically diagnosed as adenocarcinoma. Nineteen cases were suspicious for malignancy on cytology; histologically, eight of them showed adenocarcinoma. Two other cases proved to be adenocarcinoma in subsequent biopsies. Nine cases were adenomas, with severe dysplasia in five of them. Fourteen cases that were cytologically negative with minimal glandular atypia showed seven adenomas and seven nonneoplastic lesions on biopsy. Forty cases negative for malignant cells showed 19 adenomas and 21 nonspecific changes in the biopsy examination.

CONCLUSION

Colonoscopic brushing cytodiagnosis is a sensitive technique for the detection of colorectal cancer. The combination of brushing cytology and biopsy improves the accuracy of diagnosis.

Induction of ethylene biosynthesis in Nicotiana tabacum by a Trichoderma viride xylanase is correlated to the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase transcripts

Xylanase (EIX) from the fungus Trichoderma viride elicits ethylene biosynthesis in leaf tissues of Nicotiana tabacum cv Xanthi but not in cv Hicks. The increase in ethylene biosynthesis is accompanied by an accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC), an increase in extractable ACC synthase activity, and increases in ACC synthase and ACC oxidase transcripts. Priming of increases in ACC synthase and ACC oxidase transcripts. Priming of leaves with ethylene (120 microL/L, 14 h) sensitizes the tissue, resulting in an enhanced response to EIX and increases in both the in vivo ACC oxidase activity and ACC oxidase transcript level. EIX and ethylene independently induce ACC oxidase. Inhibition of ethylene biosynthesis by aminoethoxyvinylglycine is not accompanied by a reduction in ACC oxidase transcript level, indicating that ethylene biosynthesis is not required. In contrast to the differential induction of ethylene biosynthesis by EIX in Xanthi versus Hicks cultivars, both cultivars respond to a chemical stress (induced by CuSO4) by enhancing ethylene production. This induction is accompanied by an increase in ACC synthase transcript but not in that of ACC oxidase.

Laparoscopic Conservative Cystectomy of Ovarian Benign Cystic Teratoma

Laparoscopic surgery has almost totally replaced laparotomy in the management of benign adnexal conditions. Benign cystic teratoma (dermoid cyst) is one of the most common ovarian neoplasms in young women. A prospective non-randomized clinical trial was conducted. To compare the efficacy of two different methods of removal of benign cystic teratoma enucleated laparoscopically. Between January 1991 and June 1993, 37 women, all reproductive-age and desiring future fertility, underwent resection of dermoid cysts between 4 and 8 cm in diameter via laparoscopy using the three-puncture-technique. The removal of the cysts from the abdominal cavity was carried out by traction through an extended incision of one of the puncture sites in the first 17 cases (group A), and the other 20 cases (group B) were managed by embedding the cyst in a plastic bag inserted through one of the trocars, aspirating its contents, and subsequent extraction of the bag without extension of abdominal wall stab wounds. The operating time in both groups was comparable (from 35-130 minutes in group A, and 45-120 minutes in group B. However, the time required for removal of the cyst from the abdominal cavity was significantly shorter in group B (10-15 minutes) compared with group A (20-35 minutes). Spillage of cyst contents occurred in six cases in group A, and in two cases in group B. The average hospital stay in both groups was similar (22.8 hours in group A and 23.4 hours in group B). Postoperative complications in group A included one case of excessive bleeding from the extended incision, and three cases of wound infection. None of the patients in group B had short- or long-term postoperative complications. Operative laparoscopy is a safe and effective method in the management of benign cystic teratoma. We found that removal of the enucleated cyst from the abdominal cavity using a plastic bag is advantageous in terms of operating time and postoperative complication as well as in the cosmetic results compared to extraction of the cyst through an extended abdominal incision.

Exogenous endophthalmitis initially treated without systemic antibiotics

PURPOSE

In 1987, the authors reported the successful eradication of infection in 16 patients with culture-proven acute exogenous bacterial endophthalmitis using intravitreal but no systemic antibiotics. They retrospectively reviewed additional consecutive cases since then to determine if the initial omission of systemic antibiotics remained reasonable.

METHODS

Twenty patients had culture-proven endophthalmitis. Four patients initially received systemic antibiotics for orbital cellulitis (2 patients), prevention of a possible scleral buckle infection (1 patient), and ascending cholangitis (1 patient). The remaining 16 patients were treated initially with intravitreal antibiotics only.

FINDINGS

Three of these additional 16 patients ultimately required systemic antibiotics for orbital cellulitis (1 patient), infectious scleritis (1 patient), and prevention of central nervous system infection with Neisseria meningitidis (1 patient). Only in one patient who had a neglected endophthalmitis and in whom an orbital cellulitis ultimately developed were we unable to clear the intraocular infection. In the overall series of 32 patients, cultures yielded staphylococcal species in 16 eyes, gram-positive bacilli in 3, streptococcal infection in 5, gram-negative cocci in 1, and gram-negative bacilli in 7. Half of the 14 specimens (1 aqueous and 13 vitreal) collected at the time of 16 reinjections in 13 eyes yielded organisms. Half (16/32) of the eyes attained visual acuity of 20/40 or better; 87.5% (28/32) attained visual acuity of 20/400 or better.

CONCLUSIONS

Therapy with intravitreal antibiotics without systemic antibiotics is reasonable, unless the infection has extended (or is at risk to extend) beyond the globe. Such evidence includes an elevated temperature or leukocyte count, corneal ring abscess, proptosis, loss of extraocular movements, scleral abscesses or infectious scleritis, and, perhaps, the presence of a scleral buckle.

Spastic paraparesis associated with human T-lymphotropic virus type I: a clinical, serological, and genomic study in Iranian-born Mashhadi Jews

The Mashhadi-Jewish community originating in Iran is a closed and ethnically segregated population with a unique history and a high rate of intrafamilial marriage among its members. A high risk of infection by human T-lymphotropic virus type I (HTLV-I) and of adult T-cell leukemia associated with such infection was found in this population. HTLV-I is also associated with a syndrome of progressive spastic paraparesis. We therefore evaluated the occurrence of HTLV-I infection and spastic paraparesis in Mashhadi-born Iranian Jews who immigrated to Israel. We examined 83 Mashhadi-born subjects (52 women, 31 men; mean age, 61 +/- 15.5 years) and 73 age-matched non-Mashhadi Iranian-born Jews. Blood samples were tested for HTLV-I antibodies by particle agglutination test. The polymerase chain reaction (PCR) was used to detect HTLV-I proviral DNA sequences from peripheral blood mononuclear cells. Fifteen Mashhadi-born Jews (18%) were both seropositive and PCR-positive for HTLV-I. Four HTLV-I-seronegative subjects were found to be positive for HTLV-I proviral DNA by PCR. Of the 19 HTLV-I-infected subjects (11 women, 8 men; mean age, 59 +/- 16 years), 13 (68%) had spastic paraparesis of varying severity. There were no signs of myelopathy in the Mashhadi-born subjects who were negative for HTLV-I proviral DNA by PCR. None of the non-Mashhadi Iranian Jews was seropositive or PCR-positive for HTLV-I proviral DNA, or had clinical signs of spastic paraparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Tentoxin sensitivity of chloroplasts determined by codon 83 of beta subunit of proton-ATPase

Tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. In vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (ATPase) from sensitive species. Plastid atpB genes from six closely related, tentoxin-sensitive or -resistant Nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivity. The genetic relevance of this site was confirmed in Chlamydomonas reinhardtii by chloroplast transformation. The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83. Codon 83 may represent a critical site on the beta subunit that does not compete with nucleotide binding or other catalytic activities.

Reactivation of the chloroplast CF1-ATPase beta subunit by trace amounts of the CF1 alpha subunit suggests a chaperonin-like activity for CF1 alpha

Incubation of tobacco and lettuce thylakoids with 2 M LiCl in the presence of MgATP removes the beta subunit from their CF1-ATPase (CF1 beta) together with varying amounts of the CF1 alpha subunit (CF1 alpha). These 2 M LiCl extracts, as with the one obtained from spinach thylakoids (Avital, S., and Gromet-Elhanan, Z. (1991) J. Biol. Chem. 266, 7067-7072), could form active hybrid ATPases when reconstituted into inactive beta-less Rhodospirillum rubrum chromatophores. Pure CF1 beta fractions that have been isolated from these extracts could not form such active hybrids by themselves, but could do so when supplemented with trace amounts (less than 5%) of CF1 alpha. A mitochondrial F1-ATPase alpha subunit was recently reported to be a heat-shock protein, having two amino acid sequences that show a highly conserved identity with sequences found in molecular chaperones (Luis, A. M., Alconada, A., and Cuezva, J. M. (1990) J. Biol. Chem. 265, 7713-7716). These sequences are also conserved in CF1 alpha isolated from various plants, but not in F1 beta subunits. The above described reactivation of CF1 beta by trace amounts of CF1 alpha could thus be due to a chaperonin-like function of CF1 alpha, which involves the correct, active folding of isolated pure CF1 beta.

Direct selection for paternal inheritance of chloroplasts in sexual progeny of Nicotiana

The response of Nicotiana tabacum to tentoxin (chlorosis) is inherited with chloroplasts. N. tabacum var. Xanthi, a tentoxin-resistant line, was used to pollinate tentoxin-sensitive N. tabacum line 92, an alloplasmic male-sterile line containing N. undulata plastids. The seeds were mutagenized with nitrosomethylurea and germinated in the presence of tentoxin. Two percent of the seedlings had green sectors in their first true leaves. These plants were grown to maturity under non-selective conditions. Homogeneous tentoxin-resistant lines were obtained in the third generation. DNA analysis indicated, however, that selection for paternal plastids, rather than mutagenesis of maternal ones, had occurred in the tentoxin-resistant progeny. Mitochondria, which were not under selection pressure, were inherited maternally as expected. Inheritance of tentoxin-resistant paternal plastids did not require seed mutagenesis. Normally germinated seedlings that were kept under tentoxin selection consistently produced a low level of resistant green sectors in their first true leaves. Thus, normal, low-frequency transmission of paternal plastids in N. tabacum can be directly revealed by using tentoxin.

Poliomyelitis outbreak in Israel in 1988: a report with two commentaries

An outbreak of 15 cases of paralytic poliomyelitis caused by type 1 poliovirus between July and October, 1988, prompted mass vaccination of the whole Israeli population under the age of 40 years. The focus of the outbreak (12 cases) was the Hadera subdistrict, one of two subdistricts where enhanced inactivated poliovaccine (eIPV) had been the only poliovaccine used for infants since 1982. 9 of the 15 victims were 15 years or older, and 9 had previously been immunised with at least three doses of oral poliovaccine (OPV). The authors are divided in their interpretation of the findings. One group considered that the likely causative factors were the greater susceptibility of young adults previously vaccinated with OPV as well as transmission of wild poliovirus to susceptible people by children with low gut immunity against poliovirus after vaccination with eIPV; they concluded that a vaccination programme combining eIPV with OPV is the best option for Israel in future. The other group believed the causative factors were exposure to contaminated sewage or close social contact within the epidemic foci, the presence of an epidemic strain differing from the wild Mahoney and Sabin type 1 vaccine strains, and the lower seropositivity rates and geometric mean titres of neutralising antibodies to the epidemic than to vaccine strains; they believe that eIPV is the means to achieve effective control of poliomyelitis in Israel.

A point mutation in the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase affects holoenzyme assembly in Nicotiana tabacum

In photosynthetic eukaryotes, the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is composed of eight large and eight small subunits. Chloroplast-coded large subunits are found in association with chaperonins (binding proteins) of 60-61 kd to form a high mol. wt pre-assembly complex (B-complex). We have isolated a heterotrophic, maternally-inherited mutant from Nicotiana tabacum var. Xanthi which accumulates the B-complex but contains no Rubisco holoenzyme. The B-complex of the mutant dissociates in the presence of ATP, as does that of the wild-type. Processing of the nuclear-coded small subunit takes place in the mutant and neither large nor small subunits accumulate. The large subunit gene from mutant and wild-type plants was cloned and sequenced. A single nucleotide difference was found between them predicting an amino acid change of serine to phenylalanine at position 112 in the mutant. Based on the resolved structure of N.tabacum Rubisco, it is argued that the alteration at position 112 prevents holoenzyme assembly by interfering with large subunit assembly.

Nonsurgical management of uncomplicated intrahepatic hematomas following blunt abdominal trauma

A 45-year-old man who sustained blunt abdominal trauma was found to have a huge intrahepatic hematoma. Although early abdominal exploration is usually recommended for suspected hepatic injury, this case was managed nonsurgically by careful observation, with gradual resolution of the hematoma as seen on serial liver scans.

Polymorphism of acetylcholinesterase in discrete regions of the developing human fetal brain

The molecular forms and membrane association of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) and pseudocholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) were determined in the presence of protease inhibitors in dissected regions of developing human fetal brain, as compared with parallel areas from mature brain. All areas contained substantial cholinesterase activities, of which acetylcholinesterase accounted for almost all the activity. Two major forms of acetylcholinesterase activity, sedimenting at 10-11S and 4-5S, respectively, were detected on sucrose gradients and possessed similar catalytic properties, as judged by their individual Km values toward [3H]acetylcholine (ca. 4 X 10(-4) M). The ratio between these forms varied by up to four- to fivefold, both between different areas and within particular areas at various developmental stages, but reached similar values (about 5:2) in all areas of mature brain. Acetylcholinesterase activity was ca. 35-50% low-salt-soluble and 45-65% detergent-soluble in various developmental stages and brain areas, with an increase during development of the detergent-soluble fraction of the light form. In contrast, pseudocholinesterase activity was mostly low-salt-soluble and sedimented as one component of 10-11S in all areas and developmental stages. Our findings suggest noncoordinate regulation of brain acetylcholinesterase and pseudocholinesterase, and indicate that the expression of acetylcholinesterase forms within embryonic brain areas depends both on cell type composition and on development.

A human acetylcholinesterase gene identified by homology to the Ace region of Drosophila

The Ace locus of the Drosophila genome controls biosynthesis of the neurotransmitter-hydrolyzing enzyme acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7). We injected the mRNA species hybridizing with DNA fragments from this region into Xenopus oocytes, in which acetylcholinesterase mRNA is translated into active acetylcholinesterase. A 2.0-kilobase (kb) fragment of DNA from this region selectively hybridizes with Drosophila mRNA capable of inducing the biosynthesis of acetylcholinesterase in oocytes. This Drosophila DNA fragment cross-hybridized with human brain poly(A)+ RNA. We therefore used this DNA fragment as a probe for homologous sequence(s) in a human genomic DNA library and thus selected a 13.5-kb human DNA segment. DNA blot-hybridization revealed that a 2.6-kb fragment of this human DNA segment hybridizes with the Drosophila 2.0-kb DNA fragment. Both Drosophila and human fragments hybridized with a human brain mRNA species of about 7.0-kb that was barely detectable in the acetylcholinesterase-deficient HEp carcinoma. A fraction containing mRNA of similar size, extracted from human brain, induced acetylcholinesterase biosynthesis in oocytes. The human DNA fragment also was used in hybridization-selection experiments. In oocytes, hybrid-selected human brain mRNA induced acetylcholinesterase activity that was completely inhibited by 1,5-bis[4-allyldimethylammonium)phenyl]pentan-3-one dibromide but not by tetraisopropyl pyrophosphamide, a differential response to these inhibitors characteristic of "true" human brain acetylcholinesterase. These findings strongly suggest that both the Drosophila and the human DNA fragments are directly involved in controlling acetylcholinesterase biosynthesis.

Epidural analgesia for planned vaginal delivery following previous cesarean section

The effect of lumbar epidural on the course of labor, delivery, and outcome was studied in 115 parturients with a previous cesarean section who were given a trial of vaginal delivery. One hundred three women were multiparous and 12 were grandmultiparous. Uterine contractions and fetal heart rate (FHR) were monitored continuously in all patients. Epidural block was performed using 8 mL of 0.35% bupivacaine without adrenaline. Supplemental doses were administered through an indwelling catheter. At the beginning of the second stage, 10 mL of 0.25% bupivacaine was added in the sitting position. Forty-eight women delivered spontaneously and 54 had an assisted second stage. Thirteen women delivered by a repeat low segmental cesarean section; dehiscence was observed in only one woman. Fetal outcome was satisfactory and similar to that of the authors' general parturient population.

Down's syndrome in twins of unlike sex

The occurrence of Down's syndrome in both dizygotic twins appears to be very rare. A case of twins of unlike sex is reported, in which chromosomal analysis showed trisomy 21 in both of them, while the parental karyotypes were normal. This is the third reported case of such a constellation, and the second one in which infant and parental chromosomal analysis was done.

The peritoneal reaction to the translocated copper intrauterine device in women and female rats

The observation of a very severe peritoneal reaction to translocated copper-bearing devices in five women necessitated operative removal. Three Copper-T (Ortho Gyne-T, Ortho, Saunderton, High Wycombe, England) and two Copper-7 (Gravigard, Searle, High Wycombe, England) devices were involved. Similarly severe peritoneal reactions were noted in 90% of female rats who had small-sized modified copper devices inserted into their peritoneal cavities. In a control group of rats with the same device but without a copper wire, mild adhesions were observed in the majority (85%), and none had a severe peritoneal reaction. It seems evident that the severe peritoneal reaction is induced by the copper wire in both women and female rats.

Reported seizures in early childhood: a 14-year follow-up

A detailed medical history is commonly regarded as a reliable means of classifying unexplained childhood losses of consciousness into diagnostic groups such as febrile seizures, epileptic attacks and breath-holding spells. The authors have tested this assumption by comparing adolescent follow-up status with the initial medical history in 56 individuals who suffered sudden losses of consciousness before age five. Only three of these 56 were epileptic when followed-up in adolescence and only two had received anticonvulsants at any time. The prognosis for 26 individuals with afebrile seizures without evidence of breath-holding syncope was not significantly worse than that for another 16 with febrile seizures. These findings indicate a good prognosis for untreated childhood seizures of a type often classified as epileptic.

Syndrome of inappropriate antidiuretic hormone secretion in newborn infants with respiratory problems

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has not often been described in newborn infants. Of 61 infants with respiratory problems who were admitted to our neonatal intensive care unit over a six-month period from July 1978, three had SIADH, diagnosed on the basis of hyponatremia, weight gain and the excretion of highly concentrated urine. In one infant the onset of marked hyponatremia was very rapid and resulted in deep coma. The occurrence of this syndrome in 5% of infants under intensive care for neonatal respiratory problems makes it essential to monitor these infants closely for deviations in fluid and electrolyte balance.

Antibody pattern to human cytomegalovirus in patients with adenocarcinoma of the colon

The role of human cytomegalovirus (CMV) was examined according to serological patterns in 37 patients with adenocarcinoma of the colon (ACC). The sera were examined for the presence of IgG antibodies by the immunoperoxidase antibody to membrane antigens (IPAMA) method and by the complement-fixation (CF) test. Antibody determinations were also performed by the IPAMA method for three other members of the herpesvirus group: Epstein-Barr virus (EBV), herpes simplex virus (HSV) and varicella-zoster virus (VZV). Comparison groups included normal subjects, ACC patients treated with chemotherapy, and patients operated on for benign diseases. No significant difference was found in the geometric mean titers (GMTs) for CMV and the other herpesviruses in the sera of nontreated ACC patients when compared with the control groups. However, a significantly elevated antibody titer to CMV was found in chemotherapy-treated ACC patients by both the IPAMA and CF methods. In this group, elevated titers were found by the IPAMA method for EBV and HSV, but not for VZV. The significance of serological studies in elucidating the role of CMV in ACC patients is discussed.

Ovarian pregnancy and IUD

Two cases of ovarian pregnancy associated with an IUD in situ are described. One of the cases documents the first reported case of ovarian pregnancy coexisting with a Copper-T device; thus the range of types of IUDs combined with ovarian pregnancy is further extended. The consciousness of the physician of the coexistence, in combination with the wide use of updated diagnostic means, especially estimations of low values of HCG and laparoscopy, should ensure early diagnosis of ectopic pregnancies, including ovarian ones.

Thymic hormonal activity on human peripheral blood lymphocytes, in vitro. I. Reciprocal effect on T and B rosette formation

One hour incubation with the thymic extract TP-1 induced reciprocal effect on B and T rosette formation in lymphocytes of human peripheral blood. The percentage of mouse erythrocyte rosette-forming cells among lymphocytes of chronic lymphatic leukaemia was decreased by TP-1 from 54.5% to 27.1% (P < 0.001). No such effect was observed in healthy adult or cord blood lymphocytes. On the other hand, the percentage of sheep erythrocyte rosette forming cells increased significantly after TP-1 treatment, but only under conditions of active rosette formation and not in the total rosette assay. This increase was highly significant in three conditions with relative deficiency of cell-mediated immunity: newborns (17.1 to 28.3%), cancer patients (24.5 to 31.7%) and patients with lepromatous leprosy (19.8 to 31.8%). Only a small increase was noticed in healthy adults. A similarly prepared spleen extract was not active in either B or T rosette assays.