Phenylketonuria Scientific Review Conference: state of the science and future research needs

New developments in the treatment and management of phenylketonuria (PKU) as well as advances in molecular testing have emerged since the National Institutes of Health 2000 PKU Consensus Statement was released. An NIH State-of-the-Science Conference was convened in 2012 to address new findings, particularly the use of the medication sapropterin to treat some individuals with PKU, and to develop a research agenda. Prior to the 2012 conference, five working groups of experts and public members met over a 1-year period. The working groups addressed the following: long-term outcomes and management across the lifespan; PKU and pregnancy; diet control and management; pharmacologic interventions; and molecular testing, new technologies, and epidemiologic considerations. In a parallel and independent activity, an Evidence-based Practice Center supported by the Agency for Healthcare Research and Quality conducted a systematic review of adjuvant treatments for PKU; its conclusions were presented at the conference. The conference included the findings of the working groups, panel discussions from industry and international perspectives, and presentations on topics such as emerging treatments for PKU, transitioning to adult care, and the U.S. Food and Drug Administration regulatory perspective. Over 85 experts participated in the conference through information gathering and/or as presenters during the conference, and they reached several important conclusions. The most serious neurological impairments in PKU are preventable with current dietary treatment approaches. However, a variety of more subtle physical, cognitive, and behavioral consequences of even well-controlled PKU are now recognized. The best outcomes in maternal PKU occur when blood phenylalanine (Phe) concentrations are maintained between 120 and 360 μmol/L before and during pregnancy. The dietary management treatment goal for individuals with PKU is a blood Phe concentration between 120 and 360 μmol/L. The use of genotype information in the newborn period may yield valuable insights about the severity of the condition for infants diagnosed before maximal Phe levels are achieved. While emerging and established genotype-phenotype correlations may transform our understanding of PKU, establishing correlations with intellectual outcomes is more challenging. Regarding the use of sapropterin in PKU, there are significant gaps in predicting response to treatment; at least half of those with PKU will have either minimal or no response. A coordinated approach to PKU treatment improves long-term outcomes for those with PKU and facilitates the conduct of research to improve diagnosis and treatment. New drugs that are safe, efficacious, and impact a larger proportion of individuals with PKU are needed. However, it is imperative that treatment guidelines and the decision processes for determining access to treatments be tied to a solid evidence base with rigorous standards for robust and consistent data collection. The process that preceded the PKU State-of-the-Science Conference, the conference itself, and the identification of a research agenda have facilitated the development of clinical practice guidelines by professional organizations and serve as a model for other inborn errors of metabolism.

Antisense phosphorothioate oligodeoxynucleotides alter HIV type 1 replication in cultured human macrophages and peripheral blood mononuclear cells

The use of antisense oligodeoxynucleotides as antiviral drugs to combat HIV-1 infection may offer an alternative to traditional pharmacological therapies. We compared the effects of two 28-mer antisense phosphorothioate oligodeoxynucleotides [PS-oligo(dN)] with non-sequence-specific controls on HIV-1 replication in long-term human monocyte/macrophage and PBMC cultures. The anti-rev PS-oligo(dN) was complementary to the messenger RNA (mRNA) sequences derived from the overlapping region of the HIV-1 regulatory genes tat and rev, while anti-gag targeted the translational initiation site of the gag mRNA. In vitro cytotoxicity of the PS-oligo(dN) was evaluated at concentrations ranging from 0.1 to 10.0 microM for a period of 20 days. Cell survival was 100% at 0.1 microM, but decreased to 5% at 10.0 microM in relation to the untreated control cultures. Our data demonstrate that replication of both the T cell-tropic and macrophage-tropic HIV-1 strains in primary cells can be inhibited by PS-oligo(dN) in a sequence-specific and dose-dependent manner at concentrations achievable in vivo. However, the sequence-dependent antiviral activity of the utilized PS-oligo(dN) was limited to a window of specificity at concentrations between 0.25 and 1.0 microM.

Human retroviruses: their role in neoplasia and immunodeficiency

Human retroviruses (HTLVs and HIVs) infect the cells of the immune system and cause mild-to-severe immune dysfunction. They are directly or indirectly responsible for associated neoplasia and central nervous system disorders. The study of these viruses is of great importance, not only because they cause grave illnesses like AIDS, neoplasias, and CNS disease, but also because they have the ability to exert such fine levels of gene regulatory control in their replication and expression. These studies will ultimately shed light on fundamental mechanisms of genetic control in human cells in their normal state and the alterations of these controls in neoplastic or immunologically aberrant states.

Human retroviruses: cancer and AIDS

Human retroviruses are associated with a wide spectrum of clinical entities including cancers, immune deficiency and neurological disorders. They have become the focal point of all retrovirology by virtue of their extreme clinical relevance, their novel and complex biologic and genetic properties, as well as their regulation strategies. The study of these viruses is of great importance as understanding of their interactions with the host will ultimately shed light on fundamental mechanisms of genetic controls in human cells in their normal state and the alterations in these controls in neoplastic or immunologically aberrant states.

Proliferation of alveolar macrophages in hyperoxia

The effect of oxygen on the proliferative response of alveolar macrophages (AMs) was investigated. Alveolar macrophages cultured in hyperoxic atmosphere (95% O2 + 5% CO2) for 18 hours showed increased incorporation of [3H]-thymidine and proliferation in contrast to those cultured in a control atmosphere (95% air + 5% CO2). The proliferating cell was shown to be a macrophage by morphology, esterase staining, and phagocytic ability. The results suggest an oxygen-induced proliferation of AMs that may play a critical role in AM influx into the alveoli particularly at times of hyperoxia, eg, the neonatal period.

Frequency of asymptomatic genital herpes in pregnant women at term

A group of 579 asymptomatic women from Jackson Memorial Hospital, Miami, Florida, and 207 from Kaiser Foundation Hospital in Honolulu, Hawaii, admitted in labor at 37 to 40 weeks of gestation had vaginal cultures for herpes simplex virus (HSV). No cultures were positive and no neonates developed HSV infection. Seven patients gave a history of previous HSV infection in the group from Florida and three from the group in Hawaii. Herpes appears to be a low incidence risk factor in both the populations studied.

Chronic granulomatous disease in an adult

We have described a 49-year-old man with chronic granulomatous disease. The diagnosis was established by a deficiency of NBT dye reduction by neutrophils, in addition to impairment in 14C-1-glucose utilization, 125I-iodination of zymosan, chemiluminescence, superoxide radical generation, and bactericidal activity toward S aureus. This adult patient exhibits many characteristics of chronic granulomatous disease of childhood but of less severity, which may explain his unusually long survival. It is thus important to consider the diagnosis of chronic granulomatous disease not only in children but also in adult patients having the characteristic pattern of recurrent infections.

Antiviral antibodies in the sera of homosexual men: correlation with their lifestyle and drug usage

Healthy homosexual men between the ages of 21 and 65 years, from the Washington, DC (n = 162), and New York City (n = 89) areas, were studied for antibodies in the serum against cytomegalovirus (CMV), herpes simplex virus (HSV) types 1 and 2, and Epstein Barr virus (EBV) viral capsid antigen (VCA). CMV-specific antibodies were assayed by enzyme-linked immunosorbent assay (ELISA), anti-HSV-1 and -2 antibodies were measured by indirect hemagglutination (IHA), and antibodies to EBV VCA were measured by the immunofluorescence assay. Antibodies to human T lymphotrophic virus III (HTLV-III) were detected by ELISA and Western blot procedures. T lymphocytes were enumerated using OKT4 monoclonal antibody. Healthy male volunteer blood donors (n = 90) matched for age range and race proportions were used as controls. The percentage of seropositive individuals in the homosexual group was higher (90-98%) for all the viruses tested than in the control group (47-87%). Comparisons of the geometric mean titers, expressed as reciprocal serum dilutions, of seropositive individuals in homosexual (H) vs control (C) group were as follows: CMV-IgG (ELISA) H = 1:794, C = 1:68; HSV-1 (IHA) H = 1:248, C = 1:14; HSV-2 (IHA) H = 1:56, C = 1:17; EBV-VCA (IFA) H = 1:385, C = 1:131. The homosexual group also showed a higher frequency of individuals with elevated titers than the control group. The CMV IgM antibody was prevalent in 17.7% of the homosexual group and 5% of the control group; arithmetic means for ELISA values for CMV IgM were 0.207 for the homosexual group and 0.05 for the control group. In the homosexual group, the anti-CMV antibody titers increased with age (P = 0.01) and with numbers of sex partners (P = 0.06). Both anti-HSV-1 and anti-HSV-2 antibodies correlated with the number of sex partners (P = 0.04 and P = 0.05, respectively). Neither age nor partner number correlated with response to EBV, and no particular sex act was related to the EBV VCA titer level. HTLV-III seropositivity was associated with higher herpes virus group antibody titers, probably because of life style cofactors. Among the HTLV-III-seropositive subjects, those with less than or equal to 400 T-helper lymphocytes/mm3 had lower antibody titers than those with greater than 400 T-helper lymphocytes/mm3 counts, suggesting an impaired immune response secondary to immunosuppression.

Typing of herpes simplex virus by capture biotin-streptavidin enzyme-linked immunosorbent assay and comparison with restriction endonuclease analysis and immunofluorescence method using monoclonal antibodies

A sensitive enzyme-linked immunosorbent capture assay using biotin and streptavidin (capture B/SA ELISA) was developed using type-specific monoclonal antibodies for typing of herpes simplex virus. Rabbit anti-herpes simplex virus immunoglobulin G was used as the capturing antibody, and biotin-linked type-1-specific mouse monoclonal antibody or rabbit type-1- or type-2-specific polyclonal antibody served as the detecting antibody. The captured antigen was detected by an ELISA with alkaline phosphatase-conjugated streptavidin, which reacted with biotin molecules on the detector antibody. The capture B/SA ELISA was compared with other methods for efficiency and reliability in typing. Results obtained by restriction endonuclease digestion of the radiolabeled viral genome were used to determine the type (1 or 2) of clinical isolates. These results were then used as a reference for determining the accuracy of the capture B/SA ELISA, as well as that of the immunofluorescence method, both of which are easily adaptable for use in the clinical laboratory. The three methods were in perfect agreement. It was determined that both the capture B/SA ELISA and the immunofluorescence method using monoclonal antibodies provided typing results with 100% specificity and 100% sensitivity and thus were accurate and reliable. However, the ELISA was the method of choice because of its simplicity, rapidity, and use of nonradioisotopic reagents.

Reye's syndrome. Salicylate metabolism, viral antibody levels, and other factors in surviving patients and unaffected family members

To investigate possible etiologic factors for Reye's syndrome (RS), five survivors and their unaffected family members were studied. This study showed low salicylate levels among the patients with RS compared with siblings and parents when challenged with three doses of aspirin. Thus, the patients with RS, three to ten years after having had RS, exhibited normal or increased ability to metabolize aspirin. We found significantly higher antibody levels to influenza A and varicella among the patients with RS, further supporting the importance of these viral infections in the etiology of the syndrome.

Rapid detection of herpes simplex virus in clinical specimens by use of a capture biotin-streptavidin enzyme-linked immunosorbent assay

A sensitive enzyme-linked immunosorbent capture assay with biotin and streptavidin (capture B/SA ELISA) was developed to detect herpes simplex virus (HSV) antigen. Rabbit anti-HSV antibody (immunoglobulin G fraction) was coated on flat-bottom, irradiated, 96-well polystyrene microtiter plates and served to capture HSV antigen. Clinical specimens from patients with genital herpes were added. Biotin-linked rabbit anti-HSV immunoglobulin G was used as the second antibody. The antigen-antibody complex was detected with alkaline phosphatase-conjugated streptavidin, which linked to the biotin. With clinical specimens, the test had a sensitivity of 95.6% and a specificity of 91.4% when compared with the tissue culture method. The presence of HSV antigen in specimens devoid of infectivity was confirmed by blocking the reaction with unlabeled rabbit and human antibody to HSV. The level of antigen detected by the capture B/SA ELISA did not necessarily correlate with the infectivity titer of the specimens. HSV antigens could be detected by the capture B/SA ELISA when the virus infectivity was destroyed at 37 degrees C, by UV irradiation, or by Triton X-100 treatment, but not when hypochlorite treatment was used. Greater sensitivity was obtained when HSV-1- and HSV-2-specific antibody reagents were used simultaneously in each test. The capture B/SA ELISA provides a relatively rapid method (4.5 h) which is quite sensitive and specific when compared with other non-tissue culture, direct assay methods.

Chemotactic and candidacidal responses of rabbit alveolar macrophages during postnatal development and the modulating roles of surfactant in these responses

Chemotactic responses of alveolar macrophages from 1-, 7-, and 28-day-old rabbits to various concentrations of endotoxin-activated serum and n-formyl-methionyl-phenylalanine were tested utilizing both blind well and agarose plate assay systems. A dramatic increase in both the chemotactic response and responsiveness to various concentrations of chemoattractant was observed during postnatal maturation. The pattern of result was similar with both methods of assay. An age-related increase was also found to occur in the candidacidal activity of alveolar macrophages in contrast to their phagocytic uptake, which showed no age-related increases. Furthermore, the decreased function of macrophages from newborn animals correlated with a morphologically and biochemically less mature cell population which contained large amounts of phagocytosed surfactant-related material. Moreover, pretreatment of macrophages from 7- and 28-day-old animals with vesicles of surfactant-related material resulted in decreases in both chemotactic and candidacidal activity, with a paradoxical increase in their phagocytic activity. The resulting activities were similar to those of macrophages from 1-day-old animals treated with buffer alone. These data suggest that there is an age-related increase in the chemotactic and candidacidal activity of alveolar macrophages during maturation and that the decreased activity of macrophages from newborn animals is related in part to the large amount of surfactant-related material present at that time.

Comparison of standard tissue culture, tissue culture plus staining, and direct staining for detection of genital herpes simplex virus infection

Genital herpes simplex virus infection in women was studied by using conventional tissue culture (TC) virus isolation compared with short-term (24-h) TC on Lab-Tek chamber slides followed by fluorescent-antibody (FA) staining. Three different staining techniques were used after TC: (i) staining with biotin-avidin (TC-BA/FA), (ii) direct FA (TC-FA), and (iii) indirect FA. The TC-BA/FA method showed complete correlation with the TC method. The TC-FA method showed no false-positive results but 31.5% false-negative results compared with the TC method. In contrast, the TC-indirect FA method showed 11.9% false-positive results and 11.7% false-negative results. The direct staining of specimens by the biotin-avidin technique (direct BA/FA) without prior tissue culture showed 37.7% false-positive results and 11.1% false-negative results. The TC-BA/FA technique thus was as sensitive as, but more rapid than, the TC method. The quality of fluorescence was far superior in TC-BA/FA staining as compared with TC-FA or TC-indirect FA procedures. The TC-BA/FA appears to be a valuable technique in laboratory diagnosis of genital herpes infections, especially in clinical situations requiring rapid detection of the virus.

Survival of herpes simplex virus in water specimens collected from hot tubs in spa facilities and on plastic surfaces

Several health spas were closed temporarily because of possible nonvenereal spread of herpes simplex virus (HSV) in spa water at these facilities. We collected water specimens from two health spas and studied them for (1) the presence of HSV; (2) bromine (Br2), chlorine (Cl2), and pH levels; and (3) the ability of HSV to survive in water. No HSV could be isolated from the spa water specimens. Spa water had high levels of Cl2 and Br2, tap water specimens had low levels of Cl2, and distilled water had no detectable Cl2 or Br2. The addition of spa water to laboratory stock virus immediately inactivated the virus. The HSV survived four hours in the tap water and 24 hours in distilled water. The survival of HSV appeared to be related to the free halogen content of water. To approximate the conditions of survival of HSV on plastic-coated benches and seats in spa facilities, HSV was placed on plastic surfaces in a humid atmosphere at 37 to 40 degrees C. The virus was found to survive up to 4.5 hours under these conditions. The survival of HSV from human lesions may be different due to the presence of tissue secretions and proteins. Furthermore, transmission may require other factors, such as rubbing of skin or penetration through abrasions. However, survival of significant amounts of virus for 4.5 hours on plastic surfaces suggests that fomites such as these may be nonvenereal routes of HSV transmission.

Detection of genital herpes simplex infections by a tissue culture-fluorescent-antibody technique with biotin-avidin

Several cell lines were evaluated for their suitability for rapid detection of herpes simplex virus (HSV) from clinical genital specimens. Human foreskin fibroblast (Flow 7000) cells were found to be most suitable in terms of sensitivity and adherence characteristics. HSV in clinical specimens was isolated by a standard tissue culture method by monitoring the cytopathic effect, and the titers of the HSV-positive specimens were determined. More than 65% of the HSV-positive genital specimens showed titers of less than or equal to 10(4) 50% tissue culture infective doses per ml. The standard tissue culture-cytopathic effect method required 3 to 10 days for detection of HSV in clinical specimens of low infectivity. A more rapid technique was developed which involved a short-term tissue culture (24 h) on Lab-Tek chambers followed by staining with biotin-linked HSV antibody and avidin-fluorescein conjugate. Because of the high binding affinity of this system due to multiple binding of biotin to avidin and multiple attachment of biotin to the antibody molecule, the biotin-avidin fluorescent-antibody technique produced a quality of fluorescence far superior to that of the conventional fluorescent-antibody techniques. The tissue culture-biotin-avidin fluorescent-antibody method was as sensitive as the tissue culture-cytopathic effect test. This method provides an improved, more rapid test (26 h) for detecting HSV in clinical specimens.

Measurement of plasma histamine in patients with suspected food hypersensitivity

Plasma histamine determinations were performed on 15 subjects with suspected food hypersensitivity following subcutaneous food provocation with milk, egg or wheat antigens. Significant rises in plasma histamine were observed in four of the 15 subjects tested; in these four subjects positive responses were seen with a total of five food test challenges. No changes were observed in total blood counts, differential eosinophil counts in six subjects and no correlation was observed with allergen-specific IgE responses. The results of these preliminary studies lend further support to the heterogeneity of causes of food allergy and suggest that the measurement of plasma histamine may provide an additional predictive marker for the diagnosis of food allergy. This technique permits the measurement of the ultimate mediator system(s) suspected to play a pathogenetic role in many food hypersensitivities.

Milk hypersensitivity: RAST studies using new antigens generated by pepsin hydrolysis of beta-lactoglobulin

RAST was performed on sera from 28 patients with a variety of allergic symptoms, giving histories compatible with milk allergy, to investigate the occurrence of IgE antibodies to new antigens (NA) generated by in vitro pepsin hydrolysis. A variety of symptoms were associated with positive RAST scores. A positive correlation was found between the degree of RAST reactivity with undigested milk proteins and reactivity with the NA's. Reactivity to the NA's was always associated with reactivity to at least one of the undigested proteins. These findings suggest that undigested milk proteins are more reactive than digested proteins. Furthermore, antigens derived from pepsin digestion do not elicit a significant antibody response in individuals who do not allow show antibody responses to undigested proteins.

Maturation of the rabbit alveolar macrophage during animal development. III. Phagocytic and bactericidal functions

Phagocytic and bactericidal function of rabbit alveolar macrophages (AMs) lavaged from animals during the course of postnatal maturation was studied. Staphylococcus aureus and a temperature-sensitive mutant of Escherichia coli, which could not replicate at 37 degrees during the functional assays, were employed as test bacteria. Assays of the phagocytic capacity of AMs from rabbits of various age groups revealed no significant differences either in the percentage of AMs which took up bacteria (79-90%) or in the number of bacteria taken up per AM (Table 1). In contrast, bactericidal activity of AMs was found to increase with increasing animal age. No bactericidal activity was detected in AMs from newborn animals (Figs. 1 and 2), whereas AMs from 7-day-old animals exhibited at least a bacteristatic activity against S. aureus (Fig. 1) and AMs from 28-day-old rabbits showed marked bactericidal activity, essentially the same as that of AMs from adult rabbits. Adult AMs killed 75% of the S. aureus and 60% of the E. coli within 120 min (Figs. 1 and 2).

Maturation of the rabbit alveolar macrophage during animal development. I. Perinatal influx into alveoli and ultrastructural differentiation

Rabbit alveolar macrophages (AM's) were collected by tracheobronchial lavege at sequential times during animal development. The total number of cells recovered by this technique was found to increase markedly shortly before birth (Fig. 4). This apparent influx of macrophages into the alveoli continued during the first postnatal week, and, at a reduced rate, throughout the first postnatal month of life (Fig. 3). Ultrastructurally, AM's of the prenatal period resembled their monocyte precursors, and contained modest numbers of lysosomes and mitochondria, scant lamellae of ribosome-studded endoplasmic reticulum (RER), and a small Golgi apparatus (Fig. 12). A considerable amount of phagocytosed material was observed in these AM's, and consisted largely of cellular debris and two forms of surfactant-related phospholipids, termed tubular and lamellar myelin (Figs. 12-15). The quantity of these ingested phospholipids increased dramatically shortly after birth, in correlation with the known release of similar material from type II pneumocytes at this time. (Figs. 16 and 19). During the first postnatal week AM's showed a considerable increase in number of mitochondria and in the development of the RER and Golgi apparatus (Fig. 22). Increased accumulations of lipid droplets were also noted during this period. Ingested material continued to consist largely of surfactant-related phospholipids, but was less abundant at this time. By 28 days after birth, AM's were nearly morphologically mature (Fig. 25). They showed large numbers of lysosomes and mitochondria, and well developed RER and Golgi apparatuses. Ingested phospholipid material was still visualized, and the incomplete degradation of this material appeared to give rise to the dense intraphagolysosomal whorls characteristic of the mature AM.