Photodynamic therapy of normal and balloon-injured rat carotid arteries using 5-amino-levulinic acid

BACKGROUND

Although the management of atherosclerotic disease by the use of balloon angioplasty is widespread, the treatment is limited by restenosis in 30% to 50% of cases. Fibrocellular intimal hyperplasia, the main cause of restenosis, arises from proliferation and migration of medial smooth muscle cells (SMC) into the intimal layer. Factors leading to intimal hyperplasia are incompletely understood, and drugs have universally failed to influence clinical restenosis. Photodynamic therapy (PDT), the light activation of photosensitizing drugs to generate cytotoxic mediators, may have potential as prophylaxis for intimal hyperplasia. 5-Amino-levulinic acid-induced protoporphyrin IX (ALA-PPIX), a naturally occurring porphyrin precursor, and its product, -PPIX, offers a novel method of sensitization for PDT. We have investigated the pharmacokinetics of ALA in arteries and the effects of ALA-PPIX-sensitized PDT on normal and balloon-injured arteries.

METHODS AND RESULTS

ALA (20 to 200 mg/kg) was injected into healthy rats, and PPIX fluorescence was measured in the carotid arteries. In a second group of rats, the exposed carotid artery was laser illuminated (50 J/cm2, 630 nm) 30 to 90 minutes after sensitization. Three and 14 days after PDT, histological sections from treated arteries were analyzed by light microscopy. Subsequently, two new groups of rats underwent PDT (ALA, 100 mg/kg; laser, 50 J/cm2, 630 nm [at 60 to 90 minutes]). The left carotid arteries underwent balloon angioplasty by intraluminal passage of a Fogarty FG2 catheter immediately before irradiation. These rats were killed at 14 and 28 days together with laser-only, ALA-only, and untreated control rats. The arteries were perfusion-fixed in vivo. ALA-PPIX induced arterial media fluorescence in a dose-dependent manner. In the normal arteries, PDT produced a dose-dependent cellular depletion in the treated arterial segment at 3 days, and this was complete with 100 and 200 mg/kg of ALA. At 14 days, the media remained acellular, although the endothelial lining had regenerated. In the balloon-injured arteries, PDT produced complete inhibition of intimal hyperplasia at both 14 and 28 days (0%). This was significantly greater than that produced by any of the control rats (34% to 69% and 37% to 66% at the two times, respectively). Significance was at 99% using ANOVA and Fisher's PLSD test. No hemorrhage, thrombosis, or aneurysm formation was seen.

CONCLUSIONS

ALA-PPIX-sensitized PDT applied at the time of angioplasty effectively inhibits experimental intimal hyperplasia development in rats. This may offer a new approach to the management of angioplasty restenosis in patients.

Impact of special care unit for patients with advanced Alzheimer's disease on patients' discomfort and costs

OBJECTIVE

To compare outcomes in patients with the clinical diagnosis of probable dementia of the Alzheimer type (DAT) cared for in a Dementia Special Care Unit (DSCU) with those in traditional long-term care (TLTC).

DESIGN

Two-year prospective cohort study.

SETTING

Two Veterans Administration Hospitals. The DSCU concentrated on assuring patients' comfort instead of promoting maximal survival; in some patients this excluded transfer to acute medical settings, the use of antibiotics, and tube feeding.

MEASUREMENTS

Data were collected regarding disease severity, patient discomfort, use of medical resources, and mortality rate.

RESULTS

Patients at both settings were similar on baseline measures, and most were severely demented. The monthly levels of observed discomfort were lower in DSCU than in TLTC patients. The costs of medications, radiology, and laboratory procedures were lower in DSCU than in TLTC patients. DSCU patients were also transferred less frequently to an acute medical setting. The average 3-month cost for a DSCU patient was $1477 less than the cost of care for a TLTC patient. However, DSCU patients with lower severity of DAT had a higher mortality rate then TLTC patients.

CONCLUSIONS

These results suggest that management of patients with advanced DAT on a DSCU using a palliative care philosophy may result in less patient discomfort and lower costs than management on a TLTC.

Cystic fibrosis mutations in white and black Americans: an approach to identification of unknown mutations with implications for cystic fibrosis screening

OBJECTIVE

We sought to define the frequency of common cystic fibrosis mutations in white and black American probands from our geographic region.

STUDY DESIGN

Mutation analysis was performed for delta F508, G551D, G542X, R553X, S549N, an d N1303K. For probands with undetermined mutations single-stranded conformational polymorphism analysis was performed.

RESULTS

Among 40 white subjects with cystic fibrosis 26 (65%) were homozygous for delta F508, 10 (25%) were heterozygous for delta F508 and another unknown mutation, and two were homozygous for unknown mutations. Among 10 black probands one was homozygous for delta F508, seven (70%) were heterozygous for delta F508 and another unknown mutation, and one was homozygous for unknown mutations. Single-stranded conformational polymorphism analysis for selected exons was performed for 11 probands with unknown mutations. One mutation was detected in a white proband. Sequencing of this exon showed the mutation to be Q493X.

CONCLUSIONS

Thirty percent of white subjects and 80% of black subjects carried unknown mutations. In one family single-stranded conformational polymorphism was informative in identifying an undetermined cystic fibrosis mutation.

Recent growth of Medicare home health

Medicare spending for home health services has grown at an unprecedented rate since regulations were revised in 1989. To address the implications of this striking growth, it is necessary to examine the causes. This paper finds that the most important source of growth has been in the number of home health visits received per beneficiary, not in the number of beneficiaries that have been added in response to redefined eligibility criteria. Policymakers should clarify the objectives of the Medicare home health benefit, in light of increased attention to long-term care financing and expanded services for older Americans.

Farm accidents in children

OBJECTIVE

To examine the problem of accidental injury to children on farms.

DESIGN

Prospective county based study of children presenting to accident and emergency departments over 12 months with injuries sustained in a farm setting and nationwide review of fatal childhood farm accidents over the four years April 1986 to March 1990.

SETTING

Accident and emergency departments in Aberystwyth, Carmarthen, Haverfordwest, and Llanelli and fatal accidents in England, Scotland, and Wales notified to the Health and Safety Executive register.

SUBJECTS

Children aged under 16.

MAIN OUTCOME MEASURE

Death or injury after farm related accidents.

RESULTS

65 accidents were recorded, including 18 fractures. Nine accidents necessitated admission to hospital for a mean of two (range one to four) days. 13 incidents were related to tractors and other machinery; 24 were due to falls. None of these incidents were reported under the statutory notification scheme. 33 deaths were notified, eight related to tractors and allied machinery and 10 related to falling objects.

CONCLUSIONS

Although safety is improving, the farm remains a dangerous environment for children. Enforcement of existing safety legislation with significant penalties and targeting of safety education will help reduce accident rates further.

Apolipoprotein A-I metabolism in subjects with a PstI restriction fragment length polymorphism of the apoA-I gene and familial hypoalphalipoproteinemia

Familial hypoalphalipoproteinemia (hypoalpha), characterized by a decreased high density lipoprotein level, is associated with an increased incidence of premature cardiovascular disease. Restriction fragment length polymorphism analysis of genomic DNA has detected a polymorphism for the PstI restriction endonuclease near the apoA-I gene, with either a 2.2 or a 3.3 kb fragment. The latter has been previously found to occur with significantly higher frequency in probands of families with familial hypoalpha. ApoA-I was isolated from three unrelated subjects with familial hypoalpha and the 3.3 kb PstI polymorphism of the apoA-I gene, and from normal control subjects. The apoA-I from the hypoalpha subjects was structurally normal as determined by amino acid analysis and by two-dimensional gel electrophoresis. When normal apoA-I and hypoalpha apoA-I were simultaneously injected into either normal controls or hypoalpha subjects, both forms of apoA-I were catabolized at the same rate in the same subject, indicating that the hypoalpha apoA-I is also metabolically normal. Analysis of the kinetics of metabolism of apoA-I in the hypoalpha subjects, compared to the normal controls, revealed that the reduced plasma levels of apoA-I were due to an increased apoA-I fractional catabolic rate, and that the synthetic rate was normal. Based on these results, we conclude that the apoA-I gene in these hypoalpha subjects is normal, and the PstI polymorphism near the apoA-I gene, which is associated with familial hypoalpha, is likely to be a marker for a mutant gene closely linked to, but not in, the apoA-I gene.

Mast cell tumors in three ferrets

Pruritic open skin lesions (5 mm diameter) on the thorax, neck, or head of 3 ferrets were diagnosed as mast cell tumors. Diagnosis of the tumors was based on histologic examination of biopsy specimens. Histologic diagnosis was necessary because the lesions had been treated as mycotic or bacterial ulcers and did not respond to conventional treatment. Excised mast cell tumors did not recur, and malignant behavior of the tumors was not observed.

Whole blood staining in suspension for nonspecific esterase and alkaline phosphatase analyzed with a Technicon H-1

We adapted previously published methods for nonspecific esterase and alkaline phosphatase staining of white blood cells in suspension for use on a Technicon H-1 hematology analyzer. The objective was to develop a semiautomated method using whole blood that could be employed on a large scale for hematology laboratory applications, including toxicology studies, measurement of neutrophil left shift, and cytochemical classification of myeloid leukemias. The nonspecific esterase method uses the pararosaniline stain, generating the unstable substrate from two stable precursors. Whole blood is added to the substrate plus dye mix. Next, acid lysis and fixation steps destroy red cells and stabilize the monocyte staining. The alkaline phosphatase stain employs a stable naphthyl phosphate substrate and fast blue B coupling dye. The red cells are lysed with a pH 10.3 propanediol buffer, and the white blood cells are then stabilized with formalin fixation. For both methods the staining is performed off-line, and the sample is then diluted with propanediol to match the refractive index of the sheath on the H-1 analyzer, before aspiration into the direct cytometry port. A cytogram of scattered versus absorbed light is obtained. The number of cells staining and the intensity of the stain can be quantified from the cytogram.

Central hemodynamic assessment of normal term pregnancy

Ten carefully screened primiparous patients between 36 and 38 weeks' gestation underwent pulmonary artery catheterization, arterial line placement, and central hemodynamic assessment in the left lateral recumbent position. Studies were repeated in the same patients between 11 and 13 weeks post partum. Compared with the nonpregnant state, there was a significant fall in systemic vascular resistance, pulmonary vascular resistance, colloid oncotic pressure, and colloid oncotic pressure-pulmonary capillary wedge pressure gradient by the late phase of the third trimester (p less than 0.05). Pregnancy was associated with a significant rise in cardiac output and pulse in all patients (p less than 0.05). There was no significant change in pulmonary capillary wedge pressure, central venous pressure, left ventricular stroke work index, or mean arterial pressure. Normally the late phase of the third trimester is not associated with hyperdynamic left ventricular function as assessed by the left ventricular stroke work index/pulmonary capillary wedge pressure ratio.

Working with the elderly

Having recently completed my training and qualified as an RGN I would like to explain why I have left the health service.

Localization of murine X and autosomal sequences homologous to the human Y located testis-determining region

Recently a candidate gene for the primary testis-determining factor (TDF) encoding a zinc finger protein (ZFY) has been cloned from the human Y chromosome. A highly homologous X-linked copy has also been identified. Using this human sequence it is possible to identify two Y loci, an X and an autosomal locus in the mouse (Zfy-1, Zfy-2, Zfx and Zfa, respectively). Suprisingly ZFY is more homologous to the mouse X and autosomal sequences than it is to either of the Y-linked loci. Both Zfy-1 and Zfy-2 are present in the Sxr region of the Y but Zfy-2 is absent in the Sxr deletion variant Sxrb (or Sxr") suggesting it is not necessary for male determination. Extensive backcross analyses map Zfa to mouse chromosome 10 and Zfx to a 5-cM interval between anonymous X probe MDXS120 and the tabby locus (Ta). We also show that the mouse androgen receptor locus (m-AR) believed to underlie the testicular feminization mutation (Tfm) shows complete linkage to Zfx. Comparative mapping indicates that in man these genes lie in separate conserved DNA segments.

Towards an understanding of position effect variegation

Most variegating position effects are a consequence of placing a euchromatic gene adjacent to alpha-heterochromatin. In such rearrangements, the affected locus is inactivated in some cells, but not others, thereby giving rise to a mosaic tissue of mutant and wild-type cells. A detailed examination of the molecular structure of three variegating white mottled mutations of Drosophila melanogaster, all of which are inversions of the X chromosome, reveals that their euchromatic breakpoints are clustered and located approximately 25 kb downstream of the white promoter and that the heterochromatic sequences to which the white locus is adjoined are transposons. An analysis of three revertants of the wm4 mutation, created by relocating white to another euchromatic site, demonstrates that they also carry some heterochromatically derived sequences with them upon restoration of the wild-type phenotype. This suggests that variegation is not controlled from a heterochromatic sequence immediately adjacent to the variegating gene but rather from some site more internal to the heterochromatic domain itself. As a consequence of this observation we have proposed a boundary model for understanding how heterochromatic domains may be formed. It has been recognized for many years that the phenotype of variegating position effects may be altered by the presence of trans-acting dominant mutations that act to either enhance or suppress variegation. Using P-element mutagenesis, we have induced and examined 12 dominant enhancers of variegation that represent four loci on the second and third chromosomes. Most of these mutations are cytologically visible duplications or deficiencies. They exert their dominant effects through changes in the copy number of wild-type genes and can be divided into two reciprocally acting classes. Class I modifiers are genes that act as enhancers of variegation when duplicated and as suppressors when mutated or deficient. Conversely, class II modifiers are genes that enhance when mutated or deleted and suppress when duplicated. The available data indicate that, in Drosophila, there are 20-30 loci capable of dominantly modifying variegation. Of these, most appear to be of the class I type whereas only two class II modifiers have been identified so far.(ABSTRACT TRUNCATED AT 400 WORDS)

In vivo metabolism of proapolipoprotein A-I in Tangier disease

Tangier disease is a rare familial disorder characterized by extremely low levels of apolipoprotein A-I (apoA-I) and high density lipoproteins (HDL). In normal subjects, proapoA-I is secreted into plasma and converted to mature apoA-I by the cleavage of the amino-terminal six amino acids with the major isoprotein in plasma being mature apoA-I. In contrast, in Tangier disease there is a marked relative increase of proapoA-I as compared with mature apoA-I. ProapoA-I and mature apoA-I were isolated from normal and Tangier disease subjects, radio-labeled, and autologous apoA-I isoproteins injected into normal and Tangier subjects. The in vivo catabolism and conversion of proapoA-I and mature apoA-I in normal and Tangier disease subjects were quantitated. A comparison of the rate of catabolism of apoA-I isoproteins from plasma revealed a significantly faster rate of catabolism of both isoproteins of apoA-I in Tangier subjects when compared with normal subjects. The fractional conversion rate of proapoA-I to mature apoA-I was 3.9 d-1 in normal subjects and 3.6 d-1 in Tangier subjects. The results indicate that (a) apoA-I enters plasma as the pro isoprotein in both normal and Tangier subjects, (b) Tangier disease subjects have a normal fractional rate of conversion of proapoA-I to mature apoA-I, (c) proapoA-I is catabolized at the same rate as mature apoA-I in Tangier subjects, and (d) Tangier subjects catabolize both pro and mature apoA-I at a much greater rate than do normal subjects. Therefore, the relative increase in proapoA-I in Tangier disease is due to a marked decrease in mature apoA-I resulting from rapid catabolism of both pro- and mature apoA-I and not to defective conversion of proapoA-I to mature apoA-I.

Anaphylactoid and anti-ovulatory activities of LHRH antagonists in rats

Studies were conducted with LHRH antagonists examining the relationship of structure to anaphylactoid-like activity and the relationship of anaphylactoid-like activity to anti-ovulatory activity in rats. Substitution of basic amino acids appeared to enhance the anaphylactoid-like activity of these peptides but other complex structural characteristics may also be involved. Anaphylactoid and anti-ovulatory activities were clearly independent and potent LHRH antagonists with minimal anaphylactoid-like activity were identified.

Human preproapolipoprotein C-II. Analysis of major plasma isoforms

Apolipoprotein C-II plays a major role in lipid metabolism as a cofactor for lipoprotein lipase, the enzyme involved in the hydrolysis of triglyceride-rich lipoproteins. Apo-C-II is initially synthesized as a 101 amino acid protein that undergoes subsequent cotranslational cleavage of a signal peptide. Post-translational processing of apo-C-II has not been previously described. In this manuscript we identify four major plasma isoforms of apo-C-II by two-dimensional gel electrophoresis and immunoblot analysis that result from post-translational modification of apo-C-II. Neuraminidase studies have shown that two of these isoforms are early secreted sialic acid containing glycoproteins. Amino acid compositional and amino-terminal analysis have established that the major plasma isoform of apo-C-II is proapo-C-II. Proapo-C-II undergoes proteolytic cleavage of its amino-terminal hexapeptide to generate the mature form of apo-C-II. Thus, apo-C-II appears to be secreted as a carbohydrate containing proprotein that then undergoes deglycosylation and proteolytic cleavage to generate mature apo-C-II, a minor isoform in plasma. An improved understanding of the structural relationship of the various plasma isoforms of apo-C-II will help to elucidate the mechanisms involved in normal, as well as defective, processing of apo-C-II.