Rehabilitation in primary care for an ageing population: a secondary analysis from a scoping review of rehabilitation delivery models

BACKGROUND

The world population is ageing rapidly. Rehabilitation is one of the most effective health strategies for improving the health and functioning of older persons. An understanding of the current provision of rehabilitation services in primary care (PC) is needed to optimise access to rehabilitation for an ageing population. The objectives of this scoping review are a) to describe how rehabilitation services are currently offered in PC to older persons, and b) to explore age-related differences in the type of rehabilitation services provided.

METHODS

We conducted a secondary analysis of a scoping review examining rehabilitation models for older persons, with a focus on PC. Medline and Embase (2015-2022) were searched to identify studies published in English on rehabilitation services for people aged 50 + . Two authors independently screened records and extracted data using the World Health Organization (WHO)'s operational framework, the Primary Health Care Systems (PRIMASYS) approach and the WHO paper on rehabilitation in PC. Data synthesis included quantitative and qualitative analysis.

RESULTS

We synthesised data from 96 studies, 88.6% conducted in high-income countries (HICs), with 31,956 participants and identified five models for delivering rehabilitation to older persons in PC: community, home, telerehabilitation, outpatient and eldercare. Nurses, physiotherapists, and occupational therapists were the most common providers, with task-shifting reported in 15.6% of studies. The most common interventions were assessment of functioning, rehabilitation coordination, therapeutic exercise, psychological interventions, and self-management education. Environmental adaptations and assistive technology were rarely reported.

CONCLUSIONS

We described how rehabilitation services are currently provided in PC and explored age-related differences in the type of rehabilitation services received. PC can play a key role in assessing functioning and coordinating the rehabilitation process and is also well-placed to deliver rehabilitation interventions. By understanding models of rehabilitation service delivery in PC, stakeholders can work towards developing more comprehensive and accessible services that meet the diverse needs of an ageing population. Our findings, which highlight the role of rehabilitation in healthy ageing, are a valuable resource for informing policy, practice and future research in the context of the United Nations Decade of Healthy Ageing, the Rehab2030 initiative and the recently adopted WHA resolution on strengthening rehabilitation in health systems, but the conclusions can only be applied to HICs and more studies are needed that reflect the reality in low- and middle-income countries.

Platelet transfusions in a murine model of neonatal polymicrobial sepsis: Divergent effects on inflammation and mortality

BACKGROUND

Platelet transfusions (PTxs) are often given to septic preterm neonates at high platelet count thresholds in an attempt to reduce bleeding risk. However, the largest randomized controlled trial (RCT) of neonatal transfusion thresholds found higher mortality and/or major bleeding in infants transfused at higher thresholds. Using a murine model, we investigated the effects of adult PTx on neonatal sepsis-induced mortality, systemic inflammation, and platelet consumption.

STUDY DESIGN AND METHODS

Polymicrobial sepsis was induced via intraperitoneal injection of cecal slurry preparations (CS1, 2, 3) into P10 pups. Two hours after infection, pups were transfused with washed adult Green Flourescent Protein (GFP+) platelets or control. Weights, platelet counts, and GFP% were measured before 4 and 24 h post-infection. At 24 h, blood was collected for quantification of plasma cytokines.

RESULTS

The CS batches varied in 24 h mortality (11%, 73%, and 30% in CS1, 2, and 3, respectively), due to differences in bacterial composition. PTx had differential effects on sepsis-induced mortality and systemic inflammatory cytokines, increasing both in mice infected with CS1 (low mortality) and decreasing both in mice infected with CS2 and 3. In a mathematical model of platelet kinetics, the consumption of transfused adult platelets was higher than that of endogenous neonatal platelets, regardless of CS batch.

DISCUSSION

Our findings support the hypothesis that transfused adult platelets are consumed faster than endogenous neonatal platelets in sepsis and demonstrate that PTx can enhance or attenuate neonatal inflammation and mortality in a model of murine polymicrobial sepsis, depending on the composition of the inoculum and/or the severity of sepsis.

Development of gates to measure the immature platelet fraction in C57BL/6J mice using the Sysmex XN-V series multispecies hematology analyzer

The immature platelet fraction (IPF) is a measure of newly released platelets, which has been used as a marker of platelet production in multiple human studies but is not widely available in multispecies analyzers. We developed gates to measure the IPF in diluted and undiluted murine blood samples on the Sysmex XN-1000V multispecies hematology analyzer. IPF gates were created using undiluted and diluted (1/10) blood samples obtained from adult and newborn (postnatal day 10, P10) C57BL/6J wild-type (WT) mice, and from 3 murine models of thrombocytopenia: c-MPL^-/- mice, which lack the thrombopoietin receptor (hyporegenerative); antibody-mediated thrombocytopenia; and acute inflammation-induced thrombocytopenia. P10 mice were chosen because, at their size, we could consistently obtain (by terminal phlebotomy) the blood volume needed to run an undiluted sample. The undiluted blood IPF gate successfully differentiated between mechanisms of thrombocytopenia in both adult and P10 mice. For diluted samples, 2 IPF gates were generated: a thrombocytopenic (T) gate, which performed well in samples with platelet counts (PCs) <800 × 10⁹/L in adult mice and <500 × 10⁹/L in newborn mice, and a non-thrombocytopenic (NT) gate, which performed well in samples with PCs above these thresholds. PCs and IPFs measured in diluted blood using these gates agreed well with those measured in undiluted blood and had good reproducibility. These diluted gates allow for the accurate measurement of PCs and IPFs in small (10 µL) blood volumes, which can be obtained easily from adult and newborn mice as small as P1 to assess platelet production serially.

Postnatal exposure to endosulfan affects uterine development and fertility

Endosulfan is an organochlorine pesticide (OCP) used in large-scale agriculture for controlling a variety of insects and mites that attack food and non-food crops. Although endosulfan has been listed in the Stockholm Convention as a persistent organic pollutant to be worldwide banned, it is still in use in some countries. Like other OCPs, endosulfan is bioaccumulative, toxic and persistent in the environment. Human unintentional exposure may occur through air inhalation, dietary, skin contact, as well as, via transplacental route and breast feeding. Due to its lipophilic nature, endosulfan is rapidly absorbed into the gastrointestinal tract and bioaccumulates in the fatty tissues. Similar to other OCPs, endosulfan has been classified as an endocrine disrupting chemical (EDC). Endocrine action of endosulfan on development and reproductive function of males has been extensively discussed; however, endosulfan effects on the female reproductive tract have received less attention. This review provides an overview of: i) the fate and levels of endosulfan in the environment and human population, ii) the potential estrogenic properties of endosulfan in vitro and in vivo, iii) its effects on uterine development, and iv) the long-term effects on female fertility and uterine functional differentiation during early gestation.

Glyphosate induces epithelial mesenchymal transition-related changes in human endometrial Ishikawa cells via estrogen receptor pathway

Glyphosate based herbicides are the most commonly used herbicide in the world. We aimed to determine whether glyphosate (Gly) induces epithelial mesenchymal transition (EMT) - related changes in a human endometrial carcinoma cell line (Ishikawa cells), and whether the estrogen receptor (ER) pathway is involved in these changes. Ishikawa cells were exposed to Gly (0.2 μM and 2 μM) or 17β-estradiol (E2: 10-9 M). We detected that Gly increased cell migration and invasion ability compared to vehicle, as did E2. Moreover, a down regulation of E-cadherin mRNA expression was determined in response to Gly, similar to E2-effects. These results show that Gly promotes EMT-related changes in Ishikawa cells. When an ER antagonist (Fulvestrant: 10-7 M) was co-administrated with Gly, all changes were reversed, suggesting that Gly might promote EMT-related changes via ER-dependent pathway. Our results are interesting evidences of Gly effects on endometrial cancer progression via the ER-dependent pathway.

Cytomegalovirus promotes murine glioblastoma growth via pericyte recruitment and angiogenesis

Cytomegalovirus (CMV) has been implicated in glioblastoma (GBM); however, a mechanistic connection in vivo has not been established. The purpose of this study is to characterize the effects of murine CMV (MCMV) on GBM growth in murine models. Syngeneic GBM models were established in mice perinatally infected with MCMV. We found that tumor growth was markedly enhanced in MCMV+ mice, with a significant reduction in overall survival compared with that of controls (P < 0.001). We observed increased angiogenesis and tumor blood flow in MCMV+ mice. MCMV reactivation was observed in intratumoral perivascular pericytes and tumor cells in mouse and human GBM specimens, and pericyte coverage of tumor vasculature was strikingly augmented in MCMV+ mice. We identified PDGF-D as a CMV-induced factor essential for pericyte recruitment, angiogenesis, and tumor growth. The antiviral drug cidofovir improved survival in MCMV+ mice, inhibiting MCMV reactivation, PDGF-D expression, pericyte recruitment, and tumor angiogenesis. These data show that MCMV potentiates GBM growth in vivo by increased pericyte recruitment and angiogenesis due to alterations in the secretome of CMV-infected cells. Our model provides evidence for a role of CMV in GBM growth and supports the application of antiviral approaches for GBM therapy.

Thrombocytopenia is associated with severe retinopathy of prematurity

Retinopathy of prematurity (ROP) is characterized by abnormal retinal neovascularization in response to vessel loss. Platelets regulate angiogenesis and may influence ROP progression. In preterm infants, we assessed ROP and correlated with longitudinal postnatal platelet counts (n = 202). Any episode of thrombocytopenia (<100 × 109/l) at ≥30 weeks postmenstrual age (at onset of ROP) was independently associated with severe ROP, requiring treatment. Infants with severe ROP also had a lower weekly median platelet count compared with infants with less severe ROP. In a mouse oxygen-induced retinopathy model of ROP, platelet counts were lower at P17 (peak neovascularization) versus controls. Platelet transfusions at P15 and P16 suppressed neovascularization, and platelet depletion increased neovascularization. Platelet transfusion decreased retinal of vascular endothelial growth factor A (VEGFA) mRNA and protein expression; platelet depletion increased retinal VEGFA mRNA and protein expression. Resting platelets with intact granules reduced neovascularization, while thrombin-activated degranulated platelets did not. These data suggest that platelet releasate has a local antiangiogenic effect on endothelial cells to exert a downstream suppression of VEGFA in neural retina. Low platelet counts during the neovascularization phase in ROP is significantly associated with the development of severe ROP in preterm infants. In a murine model of retinopathy, platelet transfusion during the period of neovascularization suppressed retinopathy.

Developmental Stage-Specific Manifestations of Absent TPO/c-MPL Signalling in Newborn Mice

Congenital amegakaryocytic thrombocytopaenia (CAMT) is a disorder caused by c-MPL mutations that impair thrombopoietin (TPO) signalling, resulting in a near absence of megakaryocytes (MKs). While this phenotype is consistent in adults, neonates with CAMT can present with severe thrombocytopaenia despite normal MK numbers. To investigate this, we characterized MKs and platelets in newborn c-MPL –/– mice. Liver MKs in c-MPL –/– neonates were reduced in number and size compared with wild-type (WT) age-matched MKs, and exhibited ultrastructural abnormalities not found in adult c-MPL –/– MKs. Platelet counts were lower in c-MPL –/– compared with WT mice at birth and did not increase over the first 2 weeks of life. In vivo biotinylation revealed a significant reduction in the platelet half-life of c-MPL –/– newborn mice (P2) compared with age-matched WT pups, which was not associated with ultrastructural abnormalities. Genetic deletion of the pro-apoptotic Bak did not rescue the severely reduced platelet half-life of c-MPL –/– newborn mice, suggesting that it was due to factors other than platelets entering apoptosis early. Indeed, adult GFP+ (green fluorescent protein transgenic) platelets transfused into thrombocytopenic c-MPL –/– P2 pups also had a shortened lifespan, indicating the importance of cell-extrinsic factors. In addition, neonatal platelets from WT and c-MPL –/– mice exhibited reduced P-selectin surface expression following stimulation compared with adult platelets of either genotype, and platelets from c-MPL –/– neonates exhibited reduced glycoprotein IIb/IIIa (GPIIb/IIIa) activation in response to thrombin compared with age-matched WT platelets. Taken together, our findings indicate that c-MPL deficiency is associated with abnormal maturation of neonatal MKs and developmental stage-specific defects in platelet function.

Developmental differences between newborn and adult mice in response to romiplostim

Thrombocytopenia is frequent among sick neonates. While most cases are transient, some neonates experience prolonged and severe thrombocytopenia. These infants often pose diagnostic and therapeutic challenges, and may receive large numbers of platelet transfusions. Romiplostim (ROM) is a thrombopoietin (TPO)-receptor-agonist approved for treatment of adults with chronic immune thrombocytopenia (ITP). The immature platelet fraction (IPF) is a novel measure of newly produced platelets, which could aid with the diagnostic evaluation of thrombocytopenic neonates. This study had the following two objectives: (1) compare the response of newborn and adult mice to escalating doses of ROM in vivo and (2) assess the correlation between IPF and megakaryocyte (MK) mass in newborn and adult treated and untreated mice. In the first set of studies, newborn (day 1) and adult mice received a single subcutaneous (SC) dose of ROM ranging from 0 to 300 ng/g, and platelet counts were followed every other day for 14 days. Both sets of mice responded with dose-dependent platelet and IPF increases, peaking on days 5-7 post-treatment, but neonates had a blunted response (2.1-fold compared to 4.2-fold maximal increase in platelet counts, respectively). On day 5 post-treatment with 300 ng/g ROM, MKs in the bone marrow (BM) and spleen of adult mice were significantly increased in numbers and size (p < 0.0001 for both) compared to controls. MKs in the spleen and BM (but not liver) of treated neonates also increased in number, but not in size. The immature platelet count (IPC, calculated as IPF x platelet count) was highly correlated with the MK number and size in neonatal and adult BM and spleen, but not neonatal liver. The lack of response of neonatal liver MKs was not due to a cell-intrinsic reduced responsiveness to TPO, since neonatal liver progenitors were more sensitive to murine TPO (mTPO) in vitro than adult BM progenitor. In vivo treatment of newborn mice with high mTPO doses or with higher doses of ROM (900 ng/g) resulted in peak platelet counts approaching 3-fold of controls. Taken together, our data indicate that newborn mice are less responsive to ROM than adult mice in vivo, due to a combination of likely pharmacokinetic differences and developmental differences in the response of MKs to thrombopoietic stimulation, evidenced by neonatal MKs increasing in numbers but not in size. PK/PD studies in human infants treated with ROM are warranted.

Inhibition of Platelet GPVI Protects Against Myocardial Ischemia-Reperfusion Injury

OBJECTIVE

The objective of this study was to investigate the effects of platelet inhibition on myocardial ischemia-reperfusion (IR) injury.

APPROACH AND RESULTS

Timely restoration of coronary blood flow after myocardial infarction is indispensable but leads to additional damage to the heart (myocardial IR injury). Microvascular dysfunction contributes to myocardial IR injury. We hypothesized that platelet activation during IR determines microvascular perfusion and thereby the infarct size in the reperfused myocardium. The 3 phases of thrombus formation were analyzed by targeting individual key platelet-surface molecules with monoclonal antibody derivatives: (1) adhesion (anti-glycoprotein [GP]-Ib), (2) activation (anti-GPVI), and (3) aggregation (anti-GPIIbIIIa) in a murine in vivo model of left coronary artery ligation (30 minutes of ischemia followed by 24 hours of reperfusion). Infarct sizes were determined by Evans Blue/2,3,5-triphenyltetrazolium chloride staining, infiltrating neutrophils by immunohistology. Anti-GPVI treatment significantly reduced infarct size versus control, whereas anti-GPIb or anti-GPIIbIIIa antibody fragments showed no significant differences. Mechanistically, anti-GPVI antibody-mediated reduction of infarct size was not because of impaired Ca(2+) signaling or platelet degranulation because mice deficient in store-operated calcium channels (stromal interaction molecule 1, ORAI1), α-granules (Nbeal2(-/-)), and dense granule release (Unc13d(-/-)) had similar infarct sizes as control animals. Protective effects of anti-GPVI treatment were accompanied by improved microperfusion. Leukocyte infiltration was reduced in both anti-GPVI and anti-GPIb-treated IR mice.

CONCLUSIONS

Inhibition of platelet activation by an anti-GPVI antibody, but not inhibition of platelet adhesion or aggregation by an anti-GPIb or anti-GPIIbIIIa antibody significantly reduces infarct size. The reduction of the infarct size is primarily based on an improved microperfusion after anti-GPVI antibody treatment.

Sodium butyrate induces cellular senescence in neuroblastoma and prostate cancer cells

Cellular senescence leads to an irreversible block of cellular division capacity both in cell culture and in vivo. The induction of an irreversible cell cycle arrest is very useful for treatment of cancer. Histone deacetylases (HDACs) are considered as therapeutic targets to treat cancer patients. HDAC inhibitors repress cancer growth and are used in various clinical trials. Here, we analyzed whether sodium butyrate (NaBu), an inhibitor of class I and II HDACs, induces cellular senescence in neuroblastoma and prostate cancer (PCa) including an androgen-dependent as well as an androgen-independent human PCa cell line. We found that the HDAC inhibitors NaBu and valproic acid (VPA) induce cellular senescence in tumor cells. Interestingly, also an inhibitor of SIRT1, a class HDAC III, induces cellular senescence. Both neuroblastoma and human prostate cancer cell lines express senescence markers, such as the Senescence Associated-β-galactosidase (SA-β-Gal) and Senescence Associated Heterochromatin Foci (SAHF). Furthermore, NaBu down-regulates the proto-oncogenes c-Myc, Cyclin D1 and E2F1 mRNA levels. The mRNA level of the cell cycle inhibitor p16 remains unchanged whereas that of the tumor suppressor p21 is strongly up-regulated. Interestingly, NaBu treatment robustly increases reactive oxygen species (ROS) levels. These results indicate an epigenetic regulation and an association of HDAC inhibition and ROS production with cellular senescence. The data underline that tumor cells can be driven towards cellular senescence by HDAC inhibitors, which may further arise as a potent possibility for tumor suppression.

Combined in vivo depletion of glycoprotein VI and C-type lectin-like receptor 2 severely compromises hemostasis and abrogates arterial thrombosis in mice

OBJECTIVE

Platelet inhibition is a major strategy to prevent acute ischemic cardiovascular and cerebrovascular events, which may, however, be associated with an increased bleeding risk. The (hem)immunoreceptor tyrosine activation motif-bearing platelet receptors, glycoprotein VI (GPVI) and C-type lectin-like receptor 2 (CLEC-2), might be promising antithrombotic targets because they can be depleted from circulating platelets by antibody treatment, leading to sustained antithrombotic protection, but only moderately increased bleeding times in mice.

APPROACH AND RESULTS

We investigated whether both (hem)immunoreceptor tyrosine activation motif-bearing receptors can be targeted simultaneously and what the in vivo consequences of such a combined therapeutic GPVI/CLEC-2 deficiency are. We demonstrate that isolated targeting of either GPVI or CLEC-2 in vivo does not affect expression or function of the respective other receptor. Moreover, simultaneous treatment with both antibodies resulted in the sustained loss of both GPVI and CLEC-2, while leaving other activation pathways intact. However, GPVI/CLEC-2-depleted mice displayed a dramatic hemostatic defect and profound impairment of arterial thrombus formation. Furthermore, a strongly diminished hemostatic response could also be reproduced in mice genetically lacking GPVI and CLEC-2.

CONCLUSIONS

These results demonstrate that GPVI and CLEC-2 can be simultaneously downregulated in platelets in vivo and reveal an unexpected functional redundancy of the 2 receptors in hemostasis and thrombosis. These findings may have important implications of the potential use of anti-GPVI and anti-CLEC-2-based agents in the prevention of thrombotic diseases.

Exposure to anaesthetic trace gases during general anaesthesia: CobraPLA vs. LMA classic

BACKGROUND

To prospectively investigate the performance, sealing capacity and operating room (OR) staff exposure to waste anaesthetic gases during the use of the Cobra perilaryngeal airway (CobraPLA) compared with the laryngeal mask airway classic (LMA).

METHODS

Sixty patients were randomly assigned to the CobraPLA or the LMA group. Insertion time, number of insertion attempts and airway leak pressures were assessed after induction of anaesthesia. Occupational exposure to nitrous oxide (N(2)O) and Sevoflurane (SEV) was measured at the anaesthetists' breathing zone and the patients' mouth using a photoacoustic infrared spectrometer.

RESULTS

N(2)O waste gas concentrations differed significantly in the anaesthetist's breathing zone (11.7+/-7.2 p.p.m. in CobraPLA vs. 4.1+/-4.3 p.p.m. in LMA, P=0.03), whereas no difference could be shown in SEV concentrations. Correct CobraPLA positioning was possible in 28 out of 30 patients (more than one attempt necessary in five patients). Correct positioning of the LMA classic was possible in all 30 patients (more than one attempt in three patients). Peak airway pressure was higher in the CobraPLA group (16+/-3 vs. 14+/-2 cmH(2)O, P=0.01). The average leak pressure of the CobraPLA was 24+/-4 cmH(2)O, compared with 20+/-4 cmH(2)O of the LMA classic (P<0.001; all values means+/-SD).

CONCLUSION

Despite higher airway seal pressures, the CobraPLA caused higher intraoperative N(2)O trace concentrations in the anaesthetists' breathing zone.

f-Element disiloxanediolates: novel Si-O-based inorganic heterocycles

The preparation and structural characterization of scandium and f-element complexes derived from the disiloxanediolate dianion, [(Ph2SiO)2O]2-, are reported. Reactions of in situ prepared Ln[N(SiMe3)2]3 (Ln = Eu, Sm, Gd) with (Ph2SiOH)2O in different stoichiometries afforded the lanthanide disiloxanediolates [Eu[[(Ph2SiO)2O]Li(Et2O)]3] (1), [[[(Ph2SiO)2O]Li(dme)]2SmCl(dme)] (2), and [[[((Ph2SiO)2O]Li(thf)2]2GdN(SiMe3)2] (3). In situ formed (Ph2SiOLi)2O reacted with anhydrous NdBr3 (molar ratio 3:1) to give polymeric [[Nd[(Ph2SiO)2O]3[mu-Li(thf)]2[mu2LiBrLi(thf)(Et2O)]]n] (4). Treatment of 3 with Ph2Si(OH)2 in the presence of acetonitrile yielded the dilithium trisiloxanediolate derivative [[Ph2Si(OSiPh2O)2][Li(MeCN)]2]2 (5), which according to an X-ray analysis displays an Li4O4 heterocubane structure. The trinuclear scandium complex [[[(Ph2SiO)2O]Sc(acac)2]2Sc(acac)] (6) was obtained by reaction of [(C5Me5)Sc(acac)2] (C5Me5 = eta5-pentamethylcyclopentadienyl) with (Ph2SiOH)2O in a 3:2 molar ratio. Selective formation of the colorless uranium(VI) derivative [U[Ph2Si(OSiPh20)2]2[(Ph2SiO)2O]] (7) was observed when uranocene, U(eta8-C8H8)2, was allowed to react with (Ph2SiOH)2O. An X-ray diffraction study of the solvated derivative [U[Ph2Si(OSiPh2O)2]2[(Ph2SiO)2O]].Et2O.TMEDA (TMEDA= N,N,N',N'-tetramethyl-ethylenediamine) (7a) revealed the presence of both the original [(Ph2SiO)2O]2- dianion as well as the ring-enlarged [Ph2Si(OSiPh2O)2]2- ligand in the same molecule.

Personality factors and pathological gambling

Pathological gambling is a disorder in which personality factors are thought to be important. Therefore, we compared 19 male pathological gamblers with 18 male normal controls for their scores on 3 personality questionnaires. Pathological gamblers were found to have significantly higher psychoticism and neuroticism scores on the Eysenck Personality Questionnaire than controls. Gamblers also had significantly higher total hostility scores on the Hostility and Direction of Hostility Questionnaire. The possible implications of these findings are discussed.

Pathological gambling. A psychobiological study

We investigated psychobiological substrates of pathological gambling by measuring levels of norepinephrine, monoamine metabolites, and peptides in cerebrospinal fluid, plasma, and urine. Pathological gamblers had a significantly higher centrally produced fraction of cerebrospinal fluid levels of 3-methoxy-4-hydroxyphenylglycol as well as significantly greater urinary outputs of norepinephrine than controls. These results suggest that pathological gamblers may have a functional disturbance of the noradrenergic system. This system has been postulated to underlie sensation-seeking behaviors, aspects of which are thought to be abnormal among pathological gamblers.

Depressed pathological gamblers

Depressed gamblers (n = 14) were compared with normal controls (n = 41) for antecedent life events. The depressed gamblers had experienced significantly more life events, and undesirable or exit life events, during the 6 months before the onset of depression.

Imaging characteristics of a small germanium camera

A high purity germanium gamma-camera has been developed and is currently being evaluated. This camera incorporates unique performance parameters such as a 2 mm full-width spatial response function with rejection of multiple-scatter in the detector, a 2.2% FWHM energy resolution for 99 mTc, a 180 nsec paralyzable dead-time, and a 2 mu sec non-paralyzable dead-time. Imaging studies demonstrate the superior capabilities of this instrument.