Cellular stress and AMPK links metformin and diverse compounds with accelerated emergence from anesthesia and potential recovery from disorders of consciousness

The neural correlates of consciousness and the mechanisms by which general anesthesia (GA) modulate such correlates to induce loss of consciousness (LOC) has been described as one of the biggest mysteries of modern medicine. Several cellular targets and neural circuits have been identified that play a critical role in LOC induced by GA, including the GABAA receptor and ascending arousal nuclei located in the basal forebrain, hypothalamus, and brain stem. General anesthetics (GAs) including propofol and inhalational agents induce LOC in part by potentiating chloride influx through the GABAA receptor, leading to neural inhibition and LOC. Interestingly, nearly all GAs used clinically may also induce paradoxical excitation, a phenomenon in which GAs promote neuronal excitation at low doses before inducing unconsciousness. Additionally, emergence from GA, a passive process that occurs after anesthetic removal, is associated with lower anesthetic concentrations in the brain compared to doses associated with induction of GA. AMPK, an evolutionarily conserved kinase activated by cellular stress (e.g. increases in calcium [Ca2+] and/or reactive oxygen species [ROS], etc.) increases lifespan and healthspan in several model organisms. AMPK is located throughout the mammalian brain, including in neurons of the thalamus, hypothalamus, and striatum as well as in pyramidal neurons in the hippocampus and cortex. Increases in ROS and Ca2+ play critical roles in neuronal excitation and glutamate, the primary excitatory neurotransmitter in the human brain, activates AMPK in cortical neurons. Nearly every neurotransmitter released from ascending arousal circuits that promote wakefulness, arousal, and consciousness activates AMPK, including acetylcholine, histamine, orexin-A, dopamine, and norepinephrine. Several GAs that are commonly used to induce LOC in human patients also activate AMPK (e.g. propofol, sevoflurane, isoflurane, dexmedetomidine, ketamine, midazolam). Various compounds that accelerate emergence from anesthesia, thus mitigating problematic effects associated with delayed emergence such as delirium, also activate AMPK (e.g. nicotine, caffeine, forskolin, carbachol). GAs and neurotransmitters also act as preconditioning agents and the GABAA receptor inhibitor bicuculline, which reverses propofol anesthesia, also activates AMPK in cortical neurons. We propose the novel hypothesis that cellular stress-induced AMPK activation links wakefulness, arousal, and consciousness with paradoxical excitation and accelerated emergence from anesthesia. Because AMPK activators including metformin and nicotine promote proliferation and differentiation of neural stem cells located in the subventricular zone and the dentate gyrus, AMPK activation may also enhance brain repair and promote potential recovery from disorders of consciousness (i.e. minimally conscious state, vegetative state, coma).

Cellular stress and AMPK activation as a common mechanism of action linking the effects of metformin and diverse compounds that alleviate accelerated aging defects in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by an accelerated aging phenotype that typically leads to death via stroke or myocardial infarction at approximately 14.6 years of age. Most cases of HGPS have been linked to the extensive use of a cryptic splice donor site located in the LMNA gene due to a de novo mutation, generating a truncated and toxic protein known as progerin. Progerin accumulation in the nuclear membrane and within the nucleus distorts the nuclear architecture and negatively effects nuclear processes including DNA replication and repair, leading to accelerated cellular aging and premature senescence. The serine-arginine rich splicing factor SRSF1 (also known as ASF/SF2) has recently been shown to modulate alternative splicing of the LMNA gene, with SRSF1 inhibition significantly reducing progerin at both the mRNA and protein levels. In 2014, we hypothesized for the first time that compounds including metformin that induce activation of AMP-activated protein kinase (AMPK), a master metabolic regulator activated by cellular stress (e.g. increases in intracellular calcium, reactive oxygen species, and/or an AMP(ADP)/ATP ratio increase, etc.), will beneficially alter gene splicing in progeria cells by inhibiting SRSF1, thus lowering progerin levels and altering the LMNA pre-mRNA splicing ratio. Recent evidence has substantiated this hypothesis, with metformin significantly reducing the mRNA and protein levels of both SRSF1 and progerin, activating AMPK, and alleviating pathological defects in HGPS cells. Metformin has also recently been shown to beneficially alter gene splicing in normal humans. Interestingly, several chemically distinct compounds, including rapamycin, methylene blue, all-trans retinoic acid, MG132, 1α,25-dihydroxyvitamin D3, sulforaphane, and oltipraz have each been shown to alleviate accelerated aging defects in patient-derived HGPS cells. Each of these compounds has also been independently shown to induce AMPK activation. Because these compounds improve accelerated aging defects in HGPS cells either by enhancing mitochondrial functionality, increasing Nrf2 activity, inducing autophagy, or by altering gene splicing and because AMPK activation beneficially modulates each of the aforementioned processes, it is our hypothesis that cellular stress-induced AMPK activation represents an indirect yet common mechanism of action linking such chemically diverse compounds with the beneficial effects of those compounds observed in HGPS cells. As normal humans also produce progerin at much lower levels through a similar mechanism, compounds that safely induce AMPK activation may have wide-ranging implications for both normal and pathological aging.

Transposable elements, placental development, and oocyte activation: Cellular stress and AMPK links jumping genes with the creation of human life

Transposable elements (TEs), also known as "jumping genes", are DNA sequences first described by Nobel laureate Barbara McClintock that comprise nearly half of the human genome and are able to transpose or move from one genomic location to another. As McClintock also noted that a genome "shock" or stress may induce TE activation and transposition, accumulating evidence suggests that cellular stress (e.g. mediated by increases in intracellular reactive oxygen species [ROS] and calcium [Ca2+], etc.) induces TE mobilization in several model organisms and L1s (a member of the retrotransposon class of TEs) are active and capable of retrotransposition in human oocytes, human sperm, and in human neural progenitor cells. Cellular stress also plays a critical role in human placental development, with cytotrophoblast (CTB) differentiation leading to the formation of the syncytiotrophoblast (STB), a cellular layer that facilitates nutrient and gas exchange between the mother and the fetus. Syncytin-1, a protein that promotes fusion of CTB cells and is necessary for STB formation, and its receptor is found in human sperm and human oocytes, respectively, and increases in ROS and Ca2+ promote trophoblast differentiation and syncytin-1 expression. Cellular stress is also essential in promoting human oocyte maturation and activation which, similar to TE mobilization, can be induced by compounds that increase intracellular Ca2+ and ROS levels. AMPK is a master metabolic regulator activated by increases in ROS, Ca2+, and/or an AMP(ADP)/ATP ratio increase, etc. as well as compounds that induce L1 mobilization in human cells. AMPK knockdown inhibits trophoblast differentiation and AMPK-activating compounds that promote L1 mobility also enhance trophoblast differentiation. Cellular stressors that induce TE mobilization (e.g. heat shock) also promote oocyte maturation in an AMPK-dependent manner and the antibiotic ionomycin activates AMPK, promotes TE activation, and induces human oocyte activation, producing normal, healthy children. Metformin promotes AMPK-dependent telomerase activation (critical for telomere maintenance) and induces activation of the endonuclease RAG1 (promotes DNA cleavage and transposition) via AMPK. Both RAG1 and telomerase are derived from TEs. It is our hypothesis that cellular stress and AMPK links TE activation and transposition with placental development and oocyte activation, facilitating both human genome evolution and the creation of all human life. We also propose the novel observation that various cellular stress-inducing compounds (e.g. metformin, resveratrol, etc.) may facilitate beneficial TE activation and transposition and enhance fertilization and embryological development through a common mechanism of AMPK activation.

Elimination of cancer stem cells and reactivation of latent HIV-1 via AMPK activation: Common mechanism of action linking inhibition of tumorigenesis and the potential eradication of HIV-1

Although promising treatments are currently in development to slow disease progression and increase patient survival, cancer remains the second leading cause of death in the United States. Cancer treatment modalities commonly include chemoradiation and therapies that target components of aberrantly activated signaling pathways. However, treatment resistance is a common occurrence and recent evidence indicates that the existence of cancer stem cells (CSCs) may underlie the limited efficacy and inability of current treatments to effectuate a cure. CSCs, which are largely resistant to chemoradiation therapy, are a subpopulation of cancer cells that exhibit characteristics similar to embryonic stem cells (ESCs), including self-renewal, multi-lineage differentiation, and the ability to initiate tumorigenesis. Interestingly, intracellular mechanisms that sustain quiescence and promote self-renewal in adult stem cells (ASCs) and CSCs likely also function to maintain latency of HIV-1 in CD4⁺ memory T cells. Although antiretroviral therapy is highly effective in controlling HIV-1 replication, the persistence of latent but replication-competent proviruses necessitates the development of compounds that are capable of selectively reactivating the latent virus, a method known as the "shock and kill" approach. Homeostatic proliferation in central CD4⁺ memory T (T_CM) cells, a memory T cell subset that exhibits limited self-renewal and differentiation and is a primary reservoir for latent HIV-1, has been shown to reinforce and stabilize the latent reservoir in the absence of T cell activation and differentiation. HIV-1 has also been found to establish durable and long-lasting latency in a recently discovered subset of CD4⁺ T cells known as T memory stem (T_SCM) cells. T_SCM cells, compared to T_CM cells, exhibit stem cell properties that more closely match those of ESCs and ASCs, including self-renewal and differentiation into all memory T cell subsets. It is our hypothesis that activation of AMPK, a master regulator of cellular metabolism that plays a critical role in T cell activation and differentiation of ESCs and ASCs, will lead to both T cell activation-induced latent HIV-1 reactivation, facilitating virus destruction, as well as "activation", differentiation, and/or apoptosis of CSCs, thus inhibiting tumorigenesis. We also propose the novel observation that compounds that have been shown to both facilitate latent HIV-1 reactivation and promote CSC differentiation/apoptosis (e.g. bryostatin-1, JQ1, metformin, butyrate, etc.) likely do so through a common mechanism of AMPK activation.

Oocyte activation and latent HIV-1 reactivation: AMPK as a common mechanism of action linking the beginnings of life and the potential eradication of HIV-1

In all mammalian species studied to date, the initiation of oocyte activation is orchestrated through alterations in intracellular calcium (Ca(2+)) signaling. Upon sperm binding to the oocyte plasma membrane, a sperm-associated phospholipase C (PLC) isoform, PLC zeta (PLCζ), is released into the oocyte cytoplasm. PLCζ hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to produce diacylglycerol (DAG), which activates protein kinase C (PKC), and inositol 1,4,5-trisphosphate (IP3), which induces the release of Ca(2+) from endoplasmic reticulum (ER) Ca(2+) stores. Subsequent Ca(2+) oscillations are generated that drive oocyte activation to completion. Ca(2+) ionophores such as ionomycin have been successfully used to induce artificial human oocyte activation, facilitating fertilization during intra-cytoplasmic sperm injection (ICSI) procedures. Early studies have also demonstrated that the PKC activator phorbol 12-myristate 13-acetate (PMA) acts synergistically with Ca(2+) ionophores to induce parthenogenetic activation of mouse oocytes. Interestingly, the Ca(2+)-induced signaling cascade characterizing sperm or chemically-induced oocyte activation, i.e. the "shock and live" approach, bears a striking resemblance to the reactivation of latently infected HIV-1 viral reservoirs via the so called "shock and kill" approach, a method currently being pursued to eradicate HIV-1 from infected individuals. PMA and ionomycin combined, used as positive controls in HIV-1 latency reversal studies, have been shown to be extremely efficient in reactivating latent HIV-1 in CD4(+) memory T cells by inducing T cell activation. Similar to oocyte activation, T cell activation by PMA and ionomycin induces an increase in intracellular Ca(2+) concentrations and activation of DAG, PKC, and downstream Ca(2+)-dependent signaling pathways necessary for proviral transcription. Interestingly, AMPK, a master regulator of cell metabolism that is activated thorough the induction of cellular stress (e.g. increase in Ca(2+) concentration, reactive oxygen species generation, increase in AMP/ATP ratio) is essential for oocyte maturation, T cell activation, and mitochondrial function. In addition to the AMPK kinase LKB1, CaMKK2, a Ca(2+)/calmodulin-dependent kinase that also activates AMPK, is present in and activated on T cell activation and is also present in mouse oocytes and persists until the zygote and two-cell stages. It is our hypothesis that AMPK activation represents a central node linking T cell activation-induced latent HIV-1 reactivation and both physiological and artificial oocyte activation. We further propose the novel observation that various compounds that have been shown to reactivate latent HIV-1 (e.g. PMA, ionomycin, metformin, bryostatin, resveratrol, etc.) or activate oocytes (PMA, ionomycin, ethanol, puromycin, etc.) either alone or in combination likely do so via stress-induced activation of AMPK.

Alteration of splice site selection in the LMNA gene and inhibition of progerin production via AMPK activation

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic condition characterized by an accelerated aging phenotype and an average life span of 13years. Patients typically exhibit extensive pathophysiological vascular alterations, eventually resulting in death from stroke or myocardial infarction. A silent point mutation at position 1824 (C1824T) of the LMNA gene, generating a truncated form of lamin A (progerin), has been shown to be the cause of most cases of HGPS. Interestingly, this mutation induces the use of an internal 5' cryptic splice site within exon 11 of the LMNA pre-mRNA, leading to the generation of progerin via aberrant alternative splicing. The serine-arginine rich splicing factor 1 (SRSF1 or ASF/SF2) has been shown to function as an oncoprotein and is upregulated in many cancers and other age-related disorders. Indeed, SRSF1 inhibition results in a splicing ratio in the LMNA pre-mRNA favoring lamin A production over that of progerin. It is our hypothesis that activation of AMP-activated protein kinase (AMPK), a master regulator of cellular metabolism, may lead to a reduction in SRSF1 and thus a decrease in the use of the LMNA 5' cryptic splice site in exon 11 through upregulation of p32, a splicing factor-associated protein and putative mitochondrial chaperone that has been shown to inhibit SRSF1 and enhance mitochondrial DNA (mtDNA) replication and oxidative phosphorylation. AMPK activation by currently available compounds such as metformin, resveratrol, and berberine may thus have wide-ranging implications for disorders associated with increased production and accumulation of progerin.

Photonic crystal nanostructures for optical biosensing applications

We present the design, fabrication and optical investigation of photonic crystal (PhC) nanocavity drop filters for use as optical biosensors. The resonant cavity mode wavelength and Q-factor are studied as a function of the ambient refractive index and as a function of adsorbed proteins (bovine serum albumin) on the sensor surface. Experiments were performed by evanescent excitation of the cavity mode via a PhC waveguide. This in turn is coupled to a ridge waveguide that allows the introduction of a fluid flow cell on a chip. A response of partial delta lambda/delta c=(4.54+/-0.66)x10(5)nm/M is measured leading to a measured detection limit as good as Delta m=4.0+/-0.6 fg or Delta m/Delta A=(4.9+/-0.7)x10(2)pg/mm(2)in the sensitive area.

Comparing oxalic acid and sucrocide treatments for Varroa destructor (Acari: Varroidae) control under desert conditions

The effectiveness of oxalic acid (OA) and Sucrocide (S) (AVA Chemical Ventures, L.L.C., Portsmouth, NH) in reducing populations of the varroa mite Varroa destructor Anderson & Trueman (Acari: Varroidae) in honey bee, Apis mellifera L. (Hymenoptera: Apidae) colonies was measured under the desert conditions of Arizona, USA. OA and S were applied three times 7 d apart. A 3.2% solution of OA was applied in sugar syrup via a large volume syringe, trickling 5 ml per space between frames in the colony. S was applied at a concentration of 0.625% (mixed with water), according to the label directions, using a compressed air Chapin sprayer at 20 psi to apply 59 ml per frame space. Varroa mites, collected on a sticky board before, during, and after the treatments, were counted to assess the effectiveness of the treatments. This study showed that a desert climate zone did not confer any positive or negative results on the acaricidal properties of OA. Even with brood present in colonies, significant varroa mite mortality occurred in the OA colonies. In contrast, we found that Sucrocide was not effective as a mite control technique. Despite its ability to increase mite mortality in the short-term, varroa mite populations measured posttreatment were not affected any more by Sucrocide than by no treatment at all.

Fine needle aspiration cytology of mammary duct ectasia: report of a case with novel cytologic and immunocytochemical findings

BACKGROUND

Mammary duct ectasia (MDE), or periductal mastitis, is a well-defined clinical entity with a characteristic histopathologic appearance on breast biopsy specimens. However, the cytologic features of MDE have been described only recently in the cytopathology literature, and fine needle aspiration (FNA) cytologic findings are based mainly on a small number of case reports in the English-language literature. Therefore, awareness of this entity and recognition of its cytomorphologic features could aid in a more accurate diagnosis. We report the novel cytologic and immunocytochemical findings on a case of MDE that was confirmed by histologic examination on a subsequent biopsy.

CASE

We report the findings of breast FNA cytology in a 50-year-old female with a mammographically and clinically suspicious lesion. Cytology displayed a paucicellular aspirate, typified by a few scattered, cohesive clusters of ductal epithelial cells with mild nuclear atypia and distinct, peripherally located myoepithelial cells. Intermingled within the ductal elements were numerous polygonal cells with abundant, finely vacuolated cytoplasm that were immunoreactive for macrophage-specific antibody, CD68. The background consisted of a variable number of foam cells and negligible amount of blood.

CONCLUSION

The current case of MDE demonstrates cytomorphologic features that may pose diagnostic problems, particularly as a consequence of variable cytologic atypia this entity may present on FNA cytology. This diagnostic difficulty is compounded because of the abnormal mammographic and suspicious clinical findings that may be associated with MDE. CD68 immunoreactivity is a useful ancillary tool to verify the histiocytic, rather than epithelial and potentially neoplastic, nature of multivacuolated cells. To the best of our knowledge, there has been no prior reported case of MDE in the English-language literature studied utilizing CD68 antibody. This case report emphasizes that MDE is a heterogeneous entity with diverse cytomorphologic features. FNA cytology in conjunction with immunocytochemistry might permit accurate classification in the proper clinical setting.

Overexpression of a modified human malonyl-CoA decarboxylase blocks the glucose-induced increase in malonyl-CoA level but has no impact on insulin secretion in INS-1-derived (832/13) beta-cells

The long-chain acyl-CoA (LC-CoA) model of glucose-stimulated insulin secretion (GSIS) holds that secretion is linked to a glucose-induced increase in malonyl-CoA level and accumulation of LC-CoA in the cytosol. We have previously tested the validity of this proposal by overexpressing goose malonyl-CoA decarboxylase (MCD) in INS-1 cells, but these studies have been criticized due to: 1) the small insulin secretion response (2-4-fold) of the INS-1 cells used; 2) unknown contribution of the ATP-sensitive K(+) (K(ATP)) channel-independent pathway of GSIS in INS-1 cells, which has been implicated as the site at which lipids regulate insulin granule exocytosis; and 3) deletion of the N-terminal mitochondrial targeting sequence, but not the C-terminal peroxisomal targeting sequence in the goose MCD construct, raising the possibility that a significant fraction of the overexpressed enzyme was localized to peroxisomes. To address these outstanding concerns, INS-1-derived 832/13 cells, which exhibit robust K(ATP) channel-dependent and -independent pathways of GSIS, were treated with a new adenovirus encoding human MCD lacking both its mitochondrial and peroxisomal targeting sequences (AdCMV-MCD Delta 5), resulting in large increases in cytosolic MCD activity. Treatment of 832/13 cells with AdCMV-MCD Delta 5 completely blocked the glucose-induced rise in malonyl-CoA and attenuated the inhibitory effect of glucose on fatty acid oxidation. However, MCD overexpression had no effect on K(ATP) channel-dependent or -independent GSIS in 832/13 cells. Furthermore, combined treatment of 832/13 cells with AdCMV-MCD Delta 5 and triacsin C, an inhibitor of long chain acyl-CoA synthetase that reduces LC-CoA levels, did not impair GSIS. These findings extend our previous observations and are not consistent with the LC-CoA hypothesis as originally set forth.

A sequential sampling scheme for detecting infestation levels of tracheal mites (Heterostigmata: Tarsonemidae) in honey bee (Hymenoptera: Apidae) colonies

The introduction of parasitic honey bee mites, the tracheal mite, Acarapis woodi (Rennie) in 1984 and the Varroa mite, Varroa jacobsoni, in 1987, has dramatically increased the winter mortality of honey bee, Apis mellifera L., colonies in many areas of the United States. Some beekeepers have minimized their losses by routinely treating their colonies with menthol, currently the only Environmental Protection Agency-approved and available chemical for tracheal mite control. Menthol is also expensive and can interfere with honey harvesting. Because of inadequate sampling techniques and a lack of information concerning treatment, this routine treatment strategy has increased the possibility that tracheal mites will develop resistance to menthol. It is important to establish economic thresholds and treat colonies with menthol only when treatment is warranted rather than treating all colonies regardless of infestation level. The use of sequential sampling may reduce the amount of time and effort expended in examining individual colonies and determining if treatment is necessary. Sequential sampling also allows statistically based estimates of the percentage of bees in standard Langstroth hives infested with mites while controlling for the possibility of incorrectly assessing the amount of infestation. On the average, sequential sampling plans require fewer observations (bees) to reach a decision for specified probabilities of type I and type II errors than are required for fixed sampling plans, especially when the proportion of infested bees is either very low or very high. We developed a sequential sampling decision plan to allow the user to choose specific economic injury levels and the probability of making type I and type II errors which can result inconsiderable savings in time, labor and expense.

Paucity of CFTR current but modest CFTR immunoreactivity in non-diseased human ventricle

We looked for evidence of expression of the cystic fibrosis transmembrane conductance regulator (CFTR) in non-diseased human ventricle. In rabbit and guinea pig the CFTR current is present in the highest density in subepicardial ventricular myocytes. In the present study, whole-cell patch-clamp was used to determine if a CFTR-like chloride current (I(CFTR,card)) can also be activated in human subepicardial ventricular myocytes. No evidence for I(CFTR,card) was detected in these electrophysiological studies when 10 microM forskolin was applied to 23 different cells from 4 donor hearts. Consistent with our previous results, a swelling-induced chloride current (I(Cl,swell)) could be observed after cell inflation. The enzymatic digestion of human ventricle to release single myocytes may have affected our ability to detect I(CFTR,card). Therefore, we looked for anti-CFTR immunoreactivity in slices of left ventricular free wall. A strong immunoreactivity signal was observed in guinea pig ventricle, a positive control. Background staining levels were seen in dog ventricle, a negative control tissue. Human anti-CFTR immunoreactivity was slightly above background. This low level of anti-CFTR immunoreactivity is consistent both with reports that CFTR mRNA is detectable in human ventricle and our inability to detect a significant I(CFTR,card) current density.

Simultaneous X-Ray and TeV Observations of a Rapid Flare from Markarian 421

Mrk 421 was observed for about 2 days with BeppoSAX in 1998 April as part of a worldwide multiwavelength campaign. A large, well-defined flare was observed in X-rays. The same flare was observed simultaneously at TeV energies by the Whipple Observatory gamma-ray telescope. These data provide (1) the first evidence that the X-ray and TeV intensities are well correlated on timescales of hours and (2) the first exactly simultaneous X-ray and TeV spectra. The results imply that the X-ray and TeV photons derive from the same region and from the same population of relativistic electrons. The physical parameters deduced from a homogeneous synchrotron self-Compton model for the spectral energy distribution yield electron cooling times close to the observed variability timescales.

Natural history and surgical outcomes for isolated discrete subaortic stenosis in children

OBJECTIVE

To document the natural history and surgical outcomes for discrete subaortic stenosis in children.

DESIGN

Retrospective review.

SETTING

Tertiary care paediatric cardiology centres.

PATIENTS

92 children diagnosed between 1985 and 1998.

MAIN OUTCOME MEASURES

Echocardiographic left ventricular outflow gradient (echograd), and aortic insufficiency (AI).

RESULTS

The mean (SEM) age at diagnosis was 5.3 (0.4) years; the mean echograd was 30 (2) mm Hg, with AI in 22% (19/87) of patients. The echograd and incidence of AI increased to 35 (3) mm Hg and 53% (36/68) (p < 0.05) 3.6 (0.3) years later. The echograd at diagnosis predicted echograd progression and appearance of AI. 42 patients underwent surgery 2.2 (0.4) years after diagnosis. Preoperatively echograd and AI incidence increased to 58 (6) mm Hg and 76% (19/25) (p < 0.05). The echograd was 26 (4) mm Hg 3.7 (0.4) years postoperatively, with AI in 82% (31/38) of patients. Surgical morbidities included complete heart block, need for prosthetic valves, and iatrogenic ventricular septal defects. Eight patients underwent reoperation for recurrent subaortic stenosis. The age at diagnosis of 44 patients followed medically and 42 patients operated on did not differ (5.5 (0.6) v 5. 0 (0.6) years, p < 0.05). However, the echograd at diagnosis in the former was less (21 (2) v 40 (5) mm Hg, p < 0.05) and did not increase (23 (2) mm Hg) despite longer follow up (4.1 (0.4) v 2.2 (0. 4) years, p < 0.05). The incidence of AI at diagnosis and at last medical follow up was also less (14% (6/44) v 34% (13/38); 40% (17/43) v 76% (19/25), p < 0.05).

CONCLUSIONS

Many children with mild subaortic stenosis exhibit little progression of obstruction or AI and need not undergo immediate surgery. Others with more severe subaortic stenosis may progress precipitously and will benefit from early resection despite risks of surgical morbidity and recurrence.

Hydrophobic benzoic acids as inhibitors of influenza neuraminidase

Neuraminidase (NA) plays a critical role in the life cycle of influenza virus and is a target for new therapeutic agents. A new benzoic acid inhibitor (11) containing a lipophilic side chain at C-3 and a guanidine at C-5 was synthesized. The X-ray structure of 4-(N-acetylamino)-5-guanidino-3-(3-pentyloxy)benzoic acid in complex with NA revealed that the lipophilic side chain binds in a newly created hydrophobic pocket formed by the movement of Glu 278 to interact with Arg 226, whereas the guanidine of 11 interacts in a negatively charged pocket created by Asp 152, Glu 120 and Glu 229. Compound 11 was highly selective for type A (H2N2) influenza NA (IC50 1 microM) over type B (B/Lee/40) influenza NA (IC50 500 microM).

Potent inhibition of influenza sialidase by a benzoic acid containing a 2-pyrrolidinone substituent

On the basis of the lead compound 4-(N-acetylamino)-3-guanidinobenzoic acid (BANA 113), which inhibits influenza A sialidase with a Ki of 2.5 microM, several novel aromatic inhibitors of influenza sialidases were designed. In this study the N-acetyl group of BANA 113 was replaced with a 2-pyrrolidinone ring, which was designed in part to offer opportunities for introduction of spatially directed side chains that could potentially interact with the 4-, 5-, and/or 6-subsites of sialidase. While the parent structure 1-(4-carboxy-2-guanidinophenyl)pyrrolidin-2-one (8) was only a modest inhibitor of sialidase, the introduction of a hydroxymethyl or bis(hydroxymethyl) substituent at the C5' position of the 2-pyrrolidinone ring resulted in inhibitors (9 and 12, respectively) with low micromolar activity. Crystal structures of these inhibitors in complex with sialidase demonstrated that the substituents at the 5'-position of the 2-pyrrolidinone ring interact in the 4- and/or 5-subsites of the enzyme. Replacement of the guanidine in 12 with a hydrophobic 3-pentylamino group resulted in a large enhancement in binding to produce an inhibitor (14) with an IC50 of about 50 nM against influenza A sialidase, although the inhibition of influenza B sialidase was 2000-fold less. This represents the first reported example of a simple, achiral benzoic acid with potent (low nanomolar) activity as an inhibitor of influenza sialidase.

Testing the Uniform Needs Assessment Instrument for hospital discharge planning with older adults

The Uniform Needs Assessment Instrument (UNAI) was developed to systematically assess the continuing care needs of high-risk older adults in response to the 1986 Omnibus Budget Reconciliation Act. Based on previous studies, a revised UNAI was tested with 103 hospitalized older adults, comparing usual discharge planning with the UNAI. High interrater reliability was obtained. The UNAI had high (> or = 85%) sensitivity and specificity when comparing needs identification on the UNAI with subjects' reported needs at 10 to 14 days after discharge. Overall, the UNAI was more effective (sensitive and specific).

Single lead VDD pacing in children with complete heart block

OBJECTIVE

To evaluate clinically transvenous single lead VDD pacing in children with complete heart block.

DESIGN

Case series.

SETTING

Tertiary care unit of a pediatric teaching hospital.

PATIENTS

Consecutive sample of children with complete heart block requiring pacing and meeting the criteria for VDD pacing.

INTERVENTIONS

VDD single lead pacing systems (Thera VDD 8948 generator, Capsure VDD 5032 single pass lead) were implanted in nine children (mean age 10.7 years, 95% CI 8.9 to 12.3). All patients were reviewed six weeks and six months post-implantation with clinical review, detailed pacemaker interrogation, optimal device programming, treadmill exercise testing, 24 h Holter monitoring and echocardiography.

RESULTS

Mean procedure time was 62.5 mins (CI 52 to 73), mean fluoroscopy time 3.8 mins (CI 2.4 to 5.1) and mean P wave sensing amplitude 2.75 mV (CI 2.5 to 3), without significant decrease during Valsalva manoeuvre (mean 2.4 mV, CI 2.2 to 2.8). Low pacing thresholds of mean amplitude 0.39 V (CI 0.38 to 0.4) were established at pulse width 0.5 ms. Two patients required early revision--one lead dislodged and one patient had a loose set screw. Follow-up showed satisfactory pacemaker function, and mean percentage atrioventricular (AV) synchronous pacing 96.8% (CI 93 to 99) at six weeks and 97% (CI 95 to 99) at six months. P wave sensing failures were less than 1%. AV synchronous pacing was maintained for more than 99% of the period of treadmill exercise testing. There was a significant mean increase in cardiac output of 24% (CI 8 to 40, P < 0.05) at rest in VDD mode compared with VVIR mode.

CONCLUSIONS

Single lead VDD pacing is an effective and reliable method of 'physiological' rate responsive AV synchronous pacing in children with complete heart block and should be considered a viable alternative to dual lead pacing systems.

Single-tooth implant-supported restorations in the anterior maxilla

With the development of advanced surgical techniques, implants can now be utilized in a variety of applications, including replacement of a single tooth. The form of an artificial restoration is determined by the existing tooth morphology and periodontal architecture; when placing single-tooth implants, the original structure of the tooth and periodontium must be recreated. Osseointegrated single-tooth implants have a success rate that is comparable to that of implant-supported prostheses in totally edentulous patients; a 98.5% success rate has been reported following 3 years in situ. The learning objective of this article is to gain an understanding of pretreatment guidelines, such as soft tissue considerations, bone dimension, root morphology, and site preparation with osteotomes for single-tooth implant placement. The review also includes the discussion of the placement of single-tooth implants, flap design, prosthetic considerations, and the final restoration. Two case reports are presented to document and illustrate the clinical procedure.

NMR applications in complex food systems

The rheological and functional properties of food components are related to their molecular structure, morphology, and atomic mobilities. NMR provides a powerful tool for elucidating chemical structures, molecular conformations, and interactions of components in food systems. Quantitative analysis of sugars, fats, and other principal compounds in complex food systems was achieved by high-resolution liquid NMR. In addition to information available from liquid experiments, solids NMR experiments can reveal differences and changes in crystal packing of structures in food model systems. Interpretation of experimental results is enhanced by molecular modeling of key food compounds. Models for fat crystallization are carried out to enhance understanding of the molecular structures involved in the fat crystallization process. Recently, MRI has also shown significant impact on food science and technology. Some examples of NMR applications are given in this presentation.

Clinical significance of human parvovirus B19 infection in pregnancy

We present a case of human parvovirus B19 infection in a term pregnancy that resulted in rapid development of hydrops fetalis and death. Clinical aspects of this virus in pregnancy and therapeutic options are discussed.

Prenatal diagnosis of cerebellar hemorrhage: medicolegal implications

Perinatal brain damage and compromised long-term neurologic outcome have been a topic of major concern and continuing debate. Until recently the occurrence of fetal brain injury was attributed to intrapartum events. However, evidence continues to accumulate that neurologic damage can occur during fetal life unrelated to intrapartum events. We report a case of massive cerebellar hemorrhage of unknown cause diagnosed by ultrasonography at 36 weeks of gestation after decreased fetal movements. Fetal heart rate pattern and Doppler flow study of cerebral arteries are correlated with neuropathologic findings, and the medicolegal aspects of this condition are discussed.

Human antibodies reactive with beta-amyloid protein in Alzheimer's disease

Four human B cell lines established by Epstein-Barr viral transformation of B cells from a patient with a clinical diagnosis of Alzheimer's disease (AD) were found to secrete antibodies that react with plaques and cerebrovascular blood vessels in AD brain in a staining profile characteristic of beta-amyloid protein (beta-AP) in AD brain. Two of these antibodies were shown to be reactive with a rare plaque in a normal brain. In these studies, immunofluorescence and avidin-biotin complex immunoperoxidase methodology were used to determine antibody reaction, and thioflavine S was used to double label amyloid and neurofibrillary tangles. The four antibodies also reacted with neurons in normal and AD brain. Absorption studies, dot immunoblots, and enzyme-linked immunosorbent assays with beta-amyloid peptides 1-28 (beta-A1-28) and 1-40 (beta-A1-40) indicate the major determinant of the reactive epitope is located in the region of amino acids 1-28 of beta-AP. However, inhibition studies demonstrate a significant contribution to the antigenic determinant by the 29-40 region of the beta-A1-40. These antibodies represent the first human autoantibodies against beta-AP. The pathological significance of these autoantibodies is discussed.

Placental chorioangioma: prenatal diagnosis and clinical significance

We report the prenatal diagnosis of placental chorioangioma in a 32-week intrauterine pregnancy associated with polyhydramnios and enlarged fetal cardiac size that resulted in intrauterine fetal death. Ultrasound appearance, pathophysiology, and clinical significance of this entity are discussed.

Surgically created Wolff-Parkinson-White syndrome after Fontan operation

The Wolff-Parkinson-White syndrome is caused by a congenital accessory connection between the atrium and ventricle. We describe a case of symptomatic Wolff-Parkinson-White syndrome that arose after a Björk modification of the Fontan operation. Invasive electrophysiologic and intraoperative mapping indicated that the surgically created atrioventricular connection was functioning as an accessory pathway. Surgical dissection and cryoablation abolished the symptoms and the preexcitation.

Posttranslational modifications of rat proenkephalin overexpressed in Chinese hamster ovary cells

Rat proenkephalin was overexpressed in Chinese hamster ovary cells using the dihydrofolate reductase-coupled genetic amplification method. About 2 mg purified protein could be obtained from 250 ml conditioned medium; multiple successive harvests could be obtained from the same roller bottle. Degradation of proenkephalin released into the conditioned medium was reduced significantly in the presence of 2% fetal bovine serum. Forty-eight percent of recombinant proenkephalin was glycosylated; glycosylation could be entirely prevented by the addition of tunicamycin. Two-dimensional isoelectric focusing experiments showed that recombinant proenkephalin exhibited considerable charge heterogeneity, with two major unglycosylated isoelectric forms and six or seven glycosylated isoelectric forms. The estimated isoelectric points of the major unglycosylated proenkephalins were 6.0 and 6.1, while glycosylated proenkephalins ranged in pI from 5.7-6.1. Some of this isoelectric heterogeneity is due to phosphorylation; [32P] orthophosphate was readily incorporated into serine residues within newly synthesized proenkephalin.

Stretch syncope in adolescence

We describe 6 adolescents with syncope induced by stretching with the neck hyperextended. Studies of the cardiovascular responses to stretching and Valsalva in these patients were the same as controls, indicating that the mechanism is not simply Valsalva but may also involve vertebral artery compression coupled with a familial tendency to faint.

Clinical correlations of antibodies that bind, block, or modulate human acetylcholine receptors in myasthenia gravis

Acetylcholine receptor (AChR) binding and AChR modulating antibodies were found with approximately the same frequency (86%) in 349 patients with myasthenia gravis (MG). However, the total yield of positive serological results was significantly improved (90%) by assaying AChR modulating antibodies when AChR binding antibodies were not detected, because in 27 patients (8%) only one of the two tests was positive. The immunoprecipitation test for AChR blocking antibodies yielded fewer positive results (52%), but there was a significant correlation between the degree of AChR blockade and generalization of muscle weakness. In no patient was this the only positive test, because the test for AChR modulating antibodies in this study detected both AChR blocking and modulating antibodies. Human muscle AChR was used as antigen in all tests. False positive results were rare and were attributed to unexplained antibodies to 125I-alpha-Bgt (AChR binding antibody assay) and recent general anesthesia using muscle relaxants (AChR blocking and AChR modulating antibody assays). Unexplained positive results, documented previously in 5% of patients with the Lambert-Eaton myasthenic syndrome and amyotrophic lateral sclerosis (ALS), were found in this study in two of 22 patients with ALS, but in none of 427 patients with miscellaneous neurological diseases. Patients with severe generalized MG and/or thymoma tended to have higher titers of AChR binding antibodies and greater AChR modulating antibody activity. However, some patients with severe muscle weakness had low titers of antibodies, and some patients in remission or with only ocular manifestations had high titers. These seemingly paradoxical results reflect heterogeneity in the specificities, affinities, and isotypes of anti-AChR antibodies. To effect pathogenicity, antibodies must have access in vivo to extracellular antigenic sites on the AChR. One would anticipate that antibodies with greatest pathophysiological potential would be of an IgG with greatest pathophysiological potential would be of an IgG subclass that activates complement, or of a specificity that competes for acetylcholine's binding site on the receptor or readily cross-links two AChR molecules to trigger receptor modulation (e.g., by binding to sites on the duplicated alpha-subunit). In patients with suspected MG who lack serological evidence of anti-AChR antibodies, motor endplate biopsy is required for microelectrophysiological, immunochemical, and ultrastructural studies to establish with certainty whether or not the condition is acquired MG.

Screening of subsequent siblings of children who die of sudden infant death syndrome

Since the value of home apnea monitoring for subsequent siblings (subsibs) of an infant who died of sudden infant death syndrome is uncertain, we describe an evaluation and monitoring program for subsibs. Eighty subsibs were screened in hospital at an average age of 4.6 weeks. The most valuable investigations included history, physical examination, blood gas tests, and four days on an apnea monitor in hospital. Sleep recordings added no decision-making data. Only 23 infants met one of the following criteria for home apnea monitoring: (1) sleep apnea for more than 15 s (either on sleep recording or recognized by apnea alarm), (2) more than 4.5 episodes of apnea per hour of sleep, (3) periodic breathing greater than 24% of sleep time, or (4) severe parental anxiety. Twenty-two infants were monitored until they were aged 6 months and had spent two months apnea free. Twelve had apnea at home. All of the infants survived. Excessive periodic breathing alone did not seem to be a valid reason for home monitoring. Our screening program is simple, acceptable to families, and useful to select a smaller number of subsibs for home apnea monitoring.

Immunological probes for oestradiol receptors in human breast tumours

Monoclonal antibodies have been prepared against a soluble oestradiol receptor (REC) preparation partially purified from human myometrium by oestradiol affinity chromatography. The antibodies were detected by their ability to immunoprecipitate receptor bound [125I] oestradiol. One of the antibodies (D5) has been studied in detail. It will only precipitate REC after activation by salt, heat, low pH or KCNS and will not react with nuclear RE. It will not react with androgen, progesterone or glucocorticoid receptors nor with sex hormone binding globulin; it will only combine with REC from human sources. D5 recognizes a cytoplasmic 29 kdalton protein (p29) that can be separated from both type I and II soluble oestradiol binding proteins. p29 can react with activated REC and is qualitatively and quantitatively related to REC. IRMA and histochemical methods have been developed for quantitating p29 and relating its amount to receptors in human breast tumours. With both methods, highly significant (P less than 0.001) correlations with REC but not RP have been obtained. Both methods indicate that many REC-RP+ tumours contain p29. The histochemical method detects marked cellular heterogeneity in some tumours. The function of p29 is not known. It is an REC-related antigen that may be a previously undetected component of the oestradiol receptor machinery.

Cardiovascular consequences of beta-agonist tocolysis: an echocardiographic study

M-mode echocardiography was performed before and during intravenous beta-adrenergic agonist tocolysis in 13 patients with preterm labor. There was a significant increase in heart rate, fractional shortening, and calculated cardiac output. There was also a significant decrease in both end-systolic and end-diastolic left ventricular dimensions, which resolved in 24 to 36 hours. There were, however, no changes in left atrial dimensions. The data derived from this study suggest that the pulmonary edema occasionally complicating beta-adrenergic agonist tocolysis is not the result of systolic cardiac dysfunction.

Cutaneous silica granuloma

Cutaneous silica granuloma is a rare and fascinating cause of delayed scarring. Symptoms may arise many years after minor wounding if glass, sand, or other silica-containing particles have been embedded. Such granulomatous lesions are often nodular, indurated, and erythematous. They may respond to surgical excision or medical treatment, and in rare cases, they may spontaneously regress. We present one case in which three separate areas of cutaneous silica granulomas developed after a latent period of about 20 years and then involuted without intervention. The etiology and therapeutic options are discussed.

Postrhinoplasty "red nose": differential diagnosis and treatment by laser

Prior to anticipated nasal surgery, the nasal and facial skin should be examined for any vascular lesions. The skin type should be ascertained. A history of any prior nasal surgery, particularly on the nasal dorsum, should be noted. If rosacea is a clinical possibility, a trial of 1.5 to 2.0 gm q.d. of tetracycline for 6 to 8 weeks is warranted. If, after rhinoplasty, a diffuse "redness" on the nasal dorsum results and one can exclude other diagnoses, then argon laser therapy should be considered. A 3-mm punch biopsy should be obtained to see whether superficial ectatic vessels are present, a finding that would be indicative of a good result from laser therapy.