A new dynamic model system for the study of capture reactions for diffusable compounds in cytochemistry. II. Effect of the composition of the incubation medium on the trapping of phosphate ions in acid phosphatase cytochemistry

Criteria for the validation of quantitative histochemical enzyme techniques

Some practical criteria are suggested for establishing the precision, reproducibility, validity and specificity of quantitative histochemical techniques used for assaying the activities of enzymes in single cells and tissue sections. To be valid, a technique should ideally pass 12 tests. Principally these involve proving that the mean absorbance or fluorescence of the specific final reaction product (FRP) is related to section thickness, incubation time, substrate concentration and the concentration of enzyme in situ. However, the formation of appreciable amounts of non-specific FRP may interfere in the determination of the true enzyme activity. This and other difficulties are illustrated with data obtained from an investigation of Meijer's semipermeable membrane technique for assaying acid phosphatase in unfixed sections of muscle.

Membranous complexes characteristic of melanocytes derived from patients with Hermansky-Pudlak syndrome type 1 are macroautophagosomal entities of the lysosomal compartment

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder resulting from mutations in a family of genes required for efficient transport of lysosomal-related proteins from the trans-Golgi network to a target organelle. To date, there are several genetically distinct forms of HPS. Many forms of HPS exhibit aberrant trafficking of melanosome-targeted proteins resulting in incomplete melanosome biogenesis responsible for oculocutaneous albinism observed in patients. In HPS-1, melanosome-targeted proteins are localized to characteristic membranous complexes, which have morphologic similarities to macroautophagosomes. In this report, we evaluated the hypothesis that HPS-1-specific membranous complexes comprise a component of the lysosomal compartment of melanocytes. Using indirect immunofluorescence, an increase in co-localization of misrouted tyrosinase with cathepsin-L, a lysosomal cysteine protease, occurred in HPS-1 melanocytes. In addition, ribophorin II, an integral endoplasmic reticulum protein that is also a component of macroautophagosomes, and LC3, a specific marker of macrophagosomes, demonstrated localization to membranous complexes in HPS-1 melanocytes. At the electron microscopic level, the membranous complexes exhibited acid phosphatase activity and localization of exogenously supplied horseradish peroxidase (HRP)-conjugated gold particles, indicating incorporation of lysosomal and endosomal components to membranous complexes, respectively. These results confirm that membranous complexes of HPS-1 melanocytes are macroautophagosomal representatives of the lysosomal compartment.

Chromatin condensation during Scrobicularia plana spermiogenesis: a controlled and comparative enzymatic ultracytochemical study

In Scrobicularia plana testis, a nuclear acid phosphatase (ACPase) activity was detected in mid and late spermatids with the improved Gomori-chloride procedure. Lead deposits were first observed in mid spermatids at focal points over condensed chromatin strands, increasing in density as chromatin further condensated. In late spermiogenesis, lead deposits became concentrated between chromatin aggregates, and after total DNA compaction were transfered to the nuclear periphery and then shed into the cytoplasm. The specificity of the nuclear ACPase was tested against different pH values (3.9, 7.2, 7.8, 9.0), substrates (TPP, IDP, TMP, p-NCS, ATP, GTP, AMP, ADP, AMP-PNP) and inhibitors (NaF, levamisole, Zn, vanadate, theophylline). To further specify the nature of this nuclear ACPase, other enzymes were comparatively studied at their optimal pH values and at pH 5.0: nucleoside-diphosphatase, thiamin-pyrophosphatase, inorganic trimetaphosphatase, lysosomal arylsulfatases A and B, ATPase, GTPase, 5'-nucleotidase, adenylate kinase, and adenylate cyclase. Several other controls were introduced to exclude artefactual deposits induced by lead ions and tissue molecules. The results showed that the enzyme has an optimal pH at 5.0, a high specific affinity for beta-GP, and is inhibited by NaF, which suggests that it behaves as a type B-ACPase, and all controls demonstrated the specificity of the enzymic activity. Because lead deposits were specifically and temporally associated with spermatid chromatin condensation, when DNA and RNA synthesis, histones, phosphoproteins and RNA molecules strongly decrease, it is possible to suggest that the nuclear ACPase could be associated with DNA processing during chromatin compaction or involved in the hydrolysis of 2' and 3' nucleotides resulting from nuclear RNase action during RNA degradation.

Human liver pathology in peroxisomal diseases: a review including novel data

Results from electron microscopic morphometry, enzyme cytochemistry and immunolocalization in liver biopsies are reviewed. Emphasis is put on the following aspects: 1) relationship between peroxisomal size and enzyme concentration; 2) abnormal enlargement of peroxisomes in many congenital disorders with peroxisomal dysfunction; 3) normal localization of matrix enzymes in several patients with peroxisomal dysfunction, with the exception of catalase, which is mainly cytoplasmic; 4) ghost-like peroxisomes in the liver of several syndromes but not in nine cases labelled as Zellweger; 5) discrepancies between liver and cultured fibroblasts; 6) trilamellar, regularly spaced inclusions, large stacks of which are birefringent, indicate a peroxisomal dysfunction; their absence does not exclude it. The same rule holds for lipid in macrophages which is insoluble in acetone and n-hexane (after fixation). The chemical nature of these two storage materials remains unclear; and 7) proliferation of human peroxisomes is frequent in acquired liver diseases and drug toxicity, but is never accompanied by an increase in size, in contrast to the effect of the fibrates and phthalates in rat and mouse. Novel data from seven peroxisomal patients are included.

Processing of food vacuoles in the parasitic ciliate Ichthyophthirius multifiliis after exit from the host

The digestive cycle of the fish parasite Ichthyophthirius multifiliis (Ciliophora) can be divided into three main stages. During stage A the vacuoles are not yet condensed. This stage can be subdivided into an early phase in which food vacuoles contain almost intact fish cells and a later phase in which dense material accumulates at the periphery of the vacuoles. At stage B, food vacuoles attain a very high density, and at stage C the vacuole expands when the membrane pulls away from a condensed mass of substances in digestion. After its exit from the host the parasite encysts and divides, but new food vacuoles are not formed during this phase of the life cycle. Type A vacuoles are the first to disappear after exit from the host. The percentage of type B vacuoles increases during the first few hours of free life, decreasing later when the percentage of type C vacuoles starts to increase. At the end of the division phase, type C vacuoles are the most common. Food-vacuole egestion was observed only 20 h after exit from the host. At the theront stage, food vacuoles were not evident, but small vacuoles with acid phosphatase activity were observed.

The perinatal development of glucose-6-phosphatase activity distribution pattern in rat liver. A microdensitometrical study

The ontogenetic development of the intralobular distribution pattern of glucose-6-phosphatase activity in the rat liver is described in terms of histochemical changes determined with microdensitometry. A newly developed cerium-lead technique was employed and compared with the common lead technique optimized by Teutsch (1978a). The cerium technique has advantages, meets the prerequisites for quantitative determinations and yields results comparable to biochemically obtained data from microdissected tissue. The first signs of a heterogeneous distribution pattern of glucose-6-phosphatase activity are observed on the 3rd d after birth, and differences between periportal and centrolobular areas are largest around 10th and 15th d. At 30th d after birth, the adult pattern is complete with a centrolobular glucose-6-phosphatase activity of 67% of the periportal value.

Enzyme cytochemistry of the alveolar sacs and golgian-like cisternae in the ciliate Ichthyophthirius multifiliis

In the cell cortex of the parasitic ciliate Ichthyophthirius multifiliis different kinds of cisternae were observed: the alveolar sacs, thick membrane cisternae and the endoplasmic reticulum. The thick membrane cisternae possess coated dilated rims and sometimes could be observed close to the endoplasmic reticulum. Using cytochemical techniques acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in the thick membrane cisternae and in the alveolar sacs of trophozoites. In the endoplasmic reticulum acid phosphatase activity was not detected and only very small amounts of thiamine pyrophosphatase and nucleoside diphosphatase reaction product were observed. After exit from the host, a reduction in acid phosphatase activity was evident in the alveolar sacs. At theront stage acid phosphatase activity is absent from these structures. However, high thiamine pyrophosphatase and nucleoside diphosphatase activities remain in the alveolar sacs during the whole life cycle. On the other hand, acid phosphatase, thiamine pyrophosphatase and nucleoside diphosphatase activities were detected in thick membrane cisternae of theronts. Based on the morphological aspects and enzymatic content the thick membrane cisternae of the cell cortex are designated as golgian-like cisternae. The cytochemical results point out a relationship between the alveolar sacs and the Golgi complex.

Rhabdomere turnover and rhodopsin cycle: maintenance of retinula cells in Drosophila melanogaster

Visual receptor maintenance in Drosophila involves turnover of membrane. Coated pits derived from rhabdomere and plasmalemma, coated vesicles and multivesicular bodies (MVBs) of about 0.5 micron diameter characterize the early autophagic steps. Smaller electron dense bodies (0.15 micron) merge with MVBs. These are likely to be primary lysosomes as suggested by histochemistry for acid phosphatase in normal flies and an acid phosphatase deficient mutant. Aggregates of extracellular membranes confirm an earlier report that exocytotic shedding may also be employed in the fly with its open rhabdomeres. Microspectrophotometry was used to determine aspects of cycling of visual pigment to begin to correlate with what is known about membrane cycling at the ultrastructural level. Visual pigment decreases to about half 3 h after dawn then builds back gradually to maximum before dawn. Our fixations of tissue have been at the post-dawn period when autophagy may be high as inferred from visual pigment levels. In attempts to optimize our visualization of the constructive phase of the turnover process, we developed the paradigm of carotenoid 'replacement therapy'. Carotenoid replaced flies show an increase in visual pigment possibly associated with a streaming of membrane into the rhabdomere. Aged flies, studied to determine how effective maintenance is, have a unique accumulation of extracellular debris, and a small fraction of the receptors eventually degenerate.

New, improved lanthanide-based methods for the ultrastructural localization of acid and alkaline phosphatase activity

New, improved techniques for the ultrastructural localization of acid and alkaline phosphatase activity using lanthanide cations as the trapping agent were developed. Delayed penetration of the capture ions and the incubation constituents into cellular compartments was prevented by pretreating specimens with borohydride/saponin. Both the concentration of the capture agent in the incubation medium and the incubation time of the tissue specimens were optimized to achieve a satisfactory cytochemical reaction and to avoid precipitation artefacts caused by local matrix effects. The conversion of cerium phosphate into the almost insoluble cerium fluoride minimized losses of the reaction product during postincubation processing. Moreover, lanthanum itself as well as lanthanides other than cerium, e.g., gadolinium and didymium (praseodymium, neodymium), were successfully applied and can be recommended as capture agents for phosphatase cytochemistry.

Tyrosinase and acid phosphatase activities in melanocytes from avian albinos

Two forms of cutaneous albinism in the chicken were investigated for the presence and distribution of tyrosinase and acid phosphatase in melanocytes in situ and in culture. In sex-linked recessive tyrosinase-positive albinism, sal, melanocytes in regenerating feathers and neural tube-derived cultures contained morphologically normal and abnormal premelanosomes. Tyrosinase was localized primarily to the abnormal premelanosomes and probably not to the normal ones. The cells possessed, in addition, vacuoles with membranous inclusions, located in the dendrites, and capped by dopa-positive vesicles (capping vesicles). Acid phosphatase colocalized with tyrosinase in the abnormal premelanosomes and capping vesicles. Tyrosinase activity in extracts of cultured sal melanocytes equalled that of e+ control melanocytes. A tyrosinase antiserum, raised against hamster tyrosinase (Pomerantz), precipitated 2 proteins, 68 kD and 82 kD, which had a precursor-product relationship. The amount of immunoprecipitate was the same in sal and control extracts, but in sal extracts the lower-molecular-weight protein was twice as abundant as the higher-molecular-weight protein. Melanocytes in regenerating feathers from an autosomal recessive, tyrosinase-negative albino, ca, also contained morphologically normal and abnormal premelanosomes. In culture, ca melanocytes had no formal premelanosomes but only dopa-negative multivesicular bodies with wispy filamentous material. Tyrosinase activity and immunoprecipitable tyrosinase were absent. These results suggest that: the tyrosinase-positive albino, sal, has an aberration in both its tyrosinase and acid phosphatase profiles and the tyrosinase-negative albino, ca, lacks functionally and antigenically normal tyrosinase.

Matrix models. Essential tools for microscopic cytochemical research

An overview is given of the preparation and use of model systems for cytochemistry, dealing with quantitative as well as qualitative aspects. Descriptions are given of the various possibilities to prepare cytochemical matrix models, ranging from macroscopic and microscopic films, to models with more cell-like dimensions as agarose beads, artificial cells and erythrocyte ghosts. Such models allow the study of a large variety of cytochemical processes. Their potentialities are demonstrated in a number of specific applications, comprising: the study of the influence of fixation on cellular processes, reaction specificity and reaction kinetics, quality of reagents and biochemical calibration in cytochemical staining; factors influencing localization of the specific endproduct in enzyme cytochemistry; immunocytochemistry and hybridocytochemistry.

Delayed-amelanotic (DAM or Smyth) chicken: melanocyte dysfunction in vivo and in vitro

Chickens of the autoimmune delayed-amelanotic (DAM or Smyth) line develop postnatal feather amelanosis and severe visual defects, both of which are presumed to be due to a dysfunction of melanocytes and a subsequent autoimmune response that eliminates pigment cells. In this report we elucidate further the melanocytic defect. We present a morphologic analysis of the mildly affected erratic (eDAM) group of Smyth chicken whose partial depigmentation and lack of visual impairment resemble human vitiligo more so than do the complete amelanosis and blindness in the classical Smyth line. Histologically, the sequential events leading to amelanosis in the young Smyth chicken occur simultaneously in the feathers of adult eDAM Smyth chickens, and the infiltration of the feather pulp with mononuclear leukocytes correlates with the extent of local pigmentary abnormality. Cytochemical localizations of dopa-oxidase and acid-phosphatase activities in eDAM feather melanocytes suggest that melanogenesis and autophagocytosis of melanosomes occur in tandem and that the rates of both are higher in these cells than in melanocytes of normally pigmented control chickens. Assays for tyrosinase activity in feather follicles indicate a hypermelanization in eDAM feathers and in the pigmented feathers of young Smyth chicks prior to the onset of depigmentation. Finally, we report on the establishment of pure, proliferative cultures of neural crest-derived melanocytes from control and Smyth chicken embryos. The degenerative events in Smyth chicken melanocyte cultures mimic in part those of the cells in vivo and are therefore indicative of a genetic defect that is independent of the immune system.

Phosphatase cytochemistry with cerium as trapping agent. Verification of acid phosphatase and glucose-6-phosphatase reactive sites

Lead is prevalently replaced by cerium as trapping agent in phosphatase cytochemistry to prevent non-specific precipitation. Recently, substrate specific but artefactual lead precipitates have been described in the nuclear envelope (NE) and rough endoplasmic reticulum (RER) due to a local matrix effect. In the present study a verification was carried out of the localization of acid phosphatase and glucose-6-phosphatase in the NE and RER of rat peritoneal macrophages and hepatocytes respectively with cerium. It appeared that precipitates of cerium phosphate in NE and RER of peritoneal macrophages do not represent sites of acid phosphatase activity but are due to the matrix effect. However, in rat hepatocytes these organelles demonstrate true reactive sites for glucose-6-phosphatase.

Tapetal degeneration in cats with Chediak-Higashi syndrome

The Chediak-Higashi syndrome (CHS) is a genetic disorder of man, cats, and four other animal species. Enlarged cytoplasmic granules, including lysosomes and melanosomes, characterize the syndrome. Cats affected with CHS lack funduscopically visible tapeta. In normal cats, the tapetum is the light reflecting cellular layer located in the choroid. The tapetal cells contain bundles of parallel cytoplasmic rods. In this study, eyes from CHS and control cats were examined by light microscopy and transmission electron microscopy. The CHS kittens up to 14 days of age had tapeta which appeared similar to those of the controls. By 28 days of age some of the CHS tapetal rods had degenerated. Degeneration of the tapetal rods progressed rapidly and by 56 days of age there was a dramatic difference in the ultrastructural appearance of the tapetal cells. All the rods had degenerated and the contents of the tapetal cells were disorganized. The tapetal layer gradually thinned over a period of several months until the layer was absent or nearly so in CHS cats over one year of age. This study demonstrated that there is a previously overlooked degenerative component of the Chediak-Higashi syndrome.

False localization of acid phosphatase activity in the nuclear envelope and endoplasmic reticulum of peritoneal macrophages

Acid phosphatase cytochemistry using lead salt methods was performed on rat peritoneal macrophages obtained by the intraperitoneal injection of dextran five days previously. Lead precipitate was present in the nuclear envelope, the rough endoplasmic reticulum, Golgi apparatus and lysosomes in about 50% of these cells. The formation of reaction product appeared to be substrate-specific and was sensitive to sodium fluoride in all these sites. However, only in the nuclear envelope, the rough endoplasmic reticulum and Golgi apparatus could lead salt precipitation be prevented by (a) omission of the washing procedure following the incubation step, (b) postincubation in a medium containing sodium fluoride, or (c) washing in buffer containing lead salt. It is concluded that precipitation of lead salt does not prove the presence of acid phosphatase activity in these organelles. The formation of precipitate in these sites is probably due to a local matrix effect, facilitated by the persistence of acid phosphatase activity in the lysosomes and a suboptimal trapping efficiency of phosphate ions during the washing procedure which follows in the incubation step.

Depletion of secondary lysosomes in mouse macrophages infected with Leishmania mexicana amazonensis: a cytochemical study

Leishmania amastigotes lodge and multiply within parasitophorous vacuoles, which can fuse with secondary lysosomes of the host macrophages. This study examines the effect of infection with amastigotes of L. mexicana amazonensis on the secondary lysosomes of mouse macrophage cultures. The cultures were stained for the activities of two lysosomal enzyme markers, acid phosphatase and arylsulfatase, and the light microscopic observations were supplemented by electron microscopy. Nearly all noninfected macrophages contained numerous stained secondary lysosomes. The number of such lysosomes was markedly reduced 24 h postinfection, and the reduction persisted for at least 10 days. Stained secondary lysosomes reappeared after the amastigotes were destroyed by exposure of the cultures to phenazine methosulfate or by placing them at 37.5 degrees C. The depletion of lysosomes shown by cytochemical methods may reflect a high rate of fusion of the lysosomes with the parasitophorous vacuoles, exceeding the rate of formation of new secondary lysosomes. Alternatively, the parasites may inhibit the synthesis of lysosomal hydrolases, or the assembly or formation of primary or secondary lysosomes.

Digestion of prey in foraminifera is not anomalous: a correlation of light microscopic, cytochemical, and HVEM technics to study phagotrophy in two allogromiids

Correlative light, high-voltage electron and conventional electron microscopic methods were used to investigate digestion in two allogromiid foraminiferans, Allogromia sp., strain NF, and A. laticollaris Arnold. Microscopic observations showed that bacterial prey are phagocytosed by reticulopodia and are transported to the allogromiid cell body within blister-like phagosomes. Larger prey (algae, diatoms) are transported along the reticulopodial surface and are either stored extrathalamously or phagocytosed at the oral opening (peduncle). Studies of allogromiids optimally fixed and labeled with an extracellular-space label (colloidal thorium) showed that phagocytosed prey are completely enclosed by a plasma membrane envelope; this finding was corroborated by a serial-section three-dimensional reconstruction of the oral zone of one allogromiid. Cytochemical staining for acid phosphatase showed that lysosomes are absent from reticulopods but abundant in the cell body, particularly in the oral zone cytoplasm. We conclude that digestion in allogromiid foraminiferans is accomplished by a vacuole-based digestive apparatus and not by extracellular digestion within a lacunary system, as has been suggested in earlier studies.

Autophagy of mitochondria in rat bone marrow erythroid cells. Relation to nuclear extrusion

Late erythroblasts and reticulocytes from bone marrow of male Wistar rats were studied by electron-microscopic stereology. Late erythroblasts with morphological signs of nuclear extrusion (EN + erythroblasts) and late erythroblasts without these signs (EN-erythroblasts) were analysed separately. The volumes of mitochondria, autophagosomes, autophagocytosed mitochondria, autophagocytosed cytoplasm and degraded material inside autophagosomes were calculated per unit volume of cytoplasm. The results demonstrate that (1) the volume density of mitochondria in the cytoplasm decreases by 34% during maturation from (EN-)- to (EN +)-erythroblasts (P less than 0.001) and by 60% during differentiation from (EN +)-erythroblasts to reticulocytes (P less than 0.001), (2) a fivefold increase in the volume density of autophagosomes in the cytoplasm is noted during maturation from (EN-)- to (EN +)-erythroblasts (P less than 0.01), whereas the value of this parameter remains essentially unchanged during the subsequent differentiation to reticulocytes, (3) no mitochondria are found inside autophagosomes of (EN-)-erythroblasts, whereas mitochondria occupy 26% and 35%, respectively, of the autophagosomal volume in (EN +)-erythroblasts and in reticulocytes. Our results show that autophagocytosis of mitochondria starts at the moment of nuclear extrusion and continues in the bone marrow reticulocytes.

Lysosomal modifications in human proximal tubule induced by aminoglycoside treatment: visualisation by light microscopical cytochemistry

In cryostat sections of kidney biopsies, lysosomes were visualized for light microscopy by staining for acid phosphatase. Twenty patients treated with the antibiotics gentamycin, tobramycin, amikacin or netelmicin during four days were compared to ten untreated control biopsies. Because of the marked heterogeneity of enzyme reaction product through the nephron, the most strongly stained tubular sections were used for comparison. With the exception of one biopsy, all treated kidneys display heavier staining than all controls; the difference is significant. Biochemical assays of acid phosphatase activity in homogenates have not revealed this difference. The cytochemical method may be used to detect early alterations caused by nephrotoxic drugs.

Early effects of gentamicin, tobramycin, and amikacin on the human kidney

The early alterations at the level of the proximal tubule of the human kidney caused by the three most currently used aminoglycosides, gentamicin, tobramycin, and amikacin, were studied. A prospective, randomized, and comparative approach using multidisciplinary methods was used. The patients received either no treatment or one of the three aminoglycosides at a therapeutic dose for 4 days preceding nephrectomy for neoplasia partly involving one kidney. The three aminoglycosides studied induce an early lysosomal phospholipidosis. Gentamicin and tobramycin cannot be distinguished on the basis of drug tissue accumulation, lysosomal overloading, or effect on lysosomal phospholipase A1. Amikacin induces significantly lower lysosomal overloading and no loss of phospholipase A1 activity.

Glycogen autophagosomes in polymorphonuclear leukocytes induced by rickettsiae

Guinea pig polymorphonuclear leukocytes (PMNs), rich in glycogen granules, were collected from sodium-caseinate-induced peritoneal exudate. When these cells were incubated with rickettsiae, many microorganisms were phagocytized within 30 minutes at 35 degrees C and vacuoles up to 5 microns in diameter containing glycogen granules were present. Contained within these vacuoles were phagocytized extracellular material and a dense, lysosomelike substance that was acid phosphatase positive. These vacuoles, which were interpreted to be autophagosomes, were absent from PMNs that had not been stimulated with microorganisms. The number of rickettsiae in the PMN did not appear to be related to the number of autophagosomes. About 8% and 80% of thin-sectioned profiles of PMNs contained these vacuoles after 30 minutes and 4 hours incubation, respectively. After 4 hours, the PMNs contained multiple autophagosomes. Almost all of the glycogen granules were in autophagosomes in some of the cells. In some PMNs, discontinuous membranes encircled some glycogen. When PMNs were initially incubated with thorium dioxide and ferritin, and extensively washed prior to incubation with rickettsiae, glycogen was found surrounded by flattened secondary lysosomes containing the dense tracers. Some autophagosomes also contained the electron-dense tracers. These results suggest that rickettsiae induce the rapid formation of glycogen-containing autophagosomes in guinea pig peritoneal PMNs in vitro.

8;21 Translocation in acute myeloid leukemia. An ultrastructural study

An ultrastructural study was performed in four patients with acute myeloid leukemia (AML) and 8;21 translocation. The most prominent pathologic features of the leukemic cells were: (1) a high frequency of nuclear blebs, which have been associated with an aneuploid karyotype; (2) nucleocytoplasmic asynchrony in early myeloid precursors, mature polymorphonuclear leucocytes (PMN) and in megakaryocytes; (3) abnormal granule formation with the presence of Auer rods, giant granules (pseudoChediak-Higashy) containing small vesicles, primary granules, and rod-like structures; absence of secondary granules in the more mature myeloid cells and the presence of hypogranular forms; (4) the presence of "labyrinths" consisting of myeloperoxidase (MPO) negative circular tubuli, interwoven with MPO positive endoplasmic reticulum; (5) the lack of hiatus leukemicus. Although none of these features separately is pathognomonic for 8;21 AML, we can conclude that the combination of these ultrastructural findings characterizes the leukemic myeloid cells of patients with 8;21 translocation in AML.

Adult T-cell leukemia: a report on two white patients

Two white European males are reported with adult T-cell leukemia (ATL), a disease first described in Japan, but recently also in the U.K. and U.S.A. Both patients presented with lymphadenopathy, but without a mediastinal mass. In addition, one patient had skin infiltrates and the other had hepatosplenomegaly. Morphologic and ultrastructural examination of the blasts in bone marrow and lymph node biopsy revealed a predominance of polymorphic lymphoid cells with pronounced nuclear irregularities and a semi-mature chromatine pattern. Histopathology of the lymph nodes showed a diffuse infiltration with medium-sized lymphoblasts with irregular nuclei. The blasts in the bone marrow formed E rosettes with sheep erythrocytes, lacked terminal deoxynucleotidyl transferase (Tdt) activity but expressed the Ia-like antigen; although the majority of the cells reacted with a polyclonal anti-T-cell serum, they were negative for OKT3. In one patient a helper/inducer phenotype (OKT4+) was found in the lymphoblasts of bone marrow and lymph node, while in the other only in the lymph node. The difference between bone marrow and lymph node phenotype is discussed. To our knowledge, these are the first two European patients reported with ATL, a disease clearly different from convoluted T-cell acute lymphocytic leukemia.

Entry of Rickettsia tsutsugamushi into polymorphonuclear leukocytes

Factors involved in the phagocytosis and entry into polymorphonuclear leukocytes (PMNs) of Rickettsia tsutsugamushi were studied by electron microscopy. R. tsutsugamushi propagated in baby hamster kidney cell cultures was incubated with guinea pig peritoneal PMNs in vitro at 35 degrees C. Structurally intact and degenerating rickettsiae were found in phagosomes, but only intact rickettsiae escaped phagosomes and specifically entered the glycogen-rich cytoplasm. The extraphagosomal cytoplasmic rickettsiae were found within 30 min after incubation; continued incubation for 4 h increased the rickettsial entry about fourfold as seen in ultrathin sections. Most rickettsiae in phagosomes were degenerating after 4 h of incubation. When incubated at 25 degrees C, no entry and very few phagocytized rickettsiae were observed. At 40 degrees C, rickettsial entry was greatly reduced, but more rickettsiae were found in phagosomes than at 35 degrees C. Preincubation of rickettsiae at 56 degrees C for 20 min with trypsin or with 2,4-dinitrophenol inhibited entry, but many rickettsiae were in phagosomes. Glutaraldehyde or formaldehyde fixation of rickettsiae and addition of 2-deoxyglucose, iodoacetamide, cytochalasin B, colchicine, or vinblastine inhibited all rickettsial uptake by PMNs. Acid phosphatase cytochemistry of infected PMNs revealed the enzyme activity only in phagosomes with degenerated rickettsiae and not in those with intact rickettsiae. These observations indicated that rickettsiae are passively phagocytized by PMNs, and only those that are intact actively escape from phagosomes, which selectively inhibits lysosomal fusion.

Sudan Black B positivity in acute lymphoblastic leukaemia

An adult patient with Sudan Black B (SB B) positive leukaemic lymphoblasts is described. Peroxidase and naphtol AS D chloroacetate esterase stains were negative. The diagnosis of acute lymphoblastic leukaemia (ALL) was based on morphology (FAB classification: L1), on immunological marker studies (cALL+, Tdt+, Ia+) and on electron microscopy, revealed blasts, compatible with lymphoblasts. Additional proof of the diagnosis of ALL were the diffuse lymphadenopathy and the rapid response to ALL chemotherapy. Scattered azurophilic granules were present in some lymphoblasts; ultrastructurally multiple lysosomal inclusions were detected, containing small vesicles, sometimes in association with entrapped cytoplasmic organelles. The large amounts of phospholipids in these inclusions explain the Sudan Black B positivity. This type of ALL can easily be misdiagnosed as acute myeloid leukaemia.

Mechanisms of metal--salt methods in enzyme cytochemistry with special reference to acid phosphatase

This review is concerned with theoretical and experimental aspects of the factors governing the localizing potentialities of cytochemical enzyme reactions that are based on the metal-salt principle, that is, the precipitation of the primary product of the enzymatic reaction by a heavy-metal ion at the enzymatic site. Special attention is given to the lead phosphate precipitation process in acid phosphatase cytochemistry. The various model systems developed for the study of the factors involved in precipitation are described and their advantages and disadvantages discussed. Furthermore, the various cytochemical methods so far used for the demonstration of acid phosphatase activity are critically evaluated in the light of the results obtained with the model systems.

Model film studies in enzyme histochemistry with special reference to glucose-6-phosphate dehydrogenase

This paper deals with the progress made over the last few years in our understanding of enzyme cytochemical staining methods as studied using a fundamental approach with the aid of a model system of thin gel films. Although model films with a matrix of polyacrylamide have been mostly used, the properties and possible applications of other matrices are also reviewed. The chemical aspects of the entrapment of enzyme molecules into a matrix are summarized. Special attention has been paid in model film studies to the principles of the trapping reaction of a diffusable precursor resulting from the enzymatic conversion of a substrate. They are considered here as they concern the cytochemical demonstration of acid phosphatase activity with a lead salt. The effect of fixatives on different enzyme activities, the diffusion rate of substrates and chromogenic compounds to the enzyme site, and enzyme kinetics under cytochemical conditions are also discussed, since they are factors which influence the final results of the staining procedures. The advantage of model film studies in enabling the direct correlation of cytochemical and biochemical results is outlined with special reference to the cytochemical determination of glucose-6-phosphate dehydrogenase with Tetra Nitro BT. A method for determining enzyme activities in the soluble fraction of isolated cells after incorporation in model films is described for the first time. This method has proved to be highly appropriate for microscopical observations of glucose-6-phosphate dehydrogenase activity in single cells, because it results in a good morphology and no formazan precipitates outside the cells. On the other hand, this type of model film forms a bridge between fundamental model film studies using purified enzyme and quantitative enzyme cytochemistry performed in situ.

Studies on the Gomori acid phosphatase reaction: the preparation of the incubation medium

The pH of the buffer, the initial concentrations and order of mixing of the reactants, and the length of the pre-incubation at 37 degrees C have all been found to be important in determining the final composition of the Gomori acid phosphatase medium. In a conventionally prepared medium, as much as 70% of the lead salt can be precipitated as lead glycerophosphate during a 24 h pre-incubation at 37 degrees C. The use of acetate buffer at pH 4.7, mixed with the other reactants after maximal dilution, has made possible the preparation of an incubation medium which contains those concentrations of substrate, lead salt and buffer originally proposed by Gomori, and yet does not precipitate.

X-ray microanalysis of colloidal-gold-labelled lysosomes in rat liver sinusoidal cells after incubation for acid phosphatase activity

The lysosomal apparatus of the Kupffer and endothelial cells of the sinusoidal lining of the rat liver was found to take up colloidal-gold particles with a mean diameter of 5 nm, prepared according to a modified method. After incubation of the glutaraldehyde-perfusion-fixed tissue in a lead-containing medium for the demonstration of acid phosphatase activity, a reaction product was observed in the gold-loaded lysosomes. By X-ray microanalysis of such lysosomes, the presence of osmium, gold and lead was detected qualitatively in the unstained sections from the tissue, which after the incubation had been post-fixed with an OsO4-solution to which K4Fe(CN)6 had been added to enhance the contrast. The quantitative computer-assisted processing of the X-ray microanalytical data from such lysosomes enabled to determine the gold-to-lead ratio and the individual gold and lead peak intensities derived from both the M chi and L chi values in the spectra. On the basis of these results and those obtained similarly in control lysosomes containing either only gold or only lead phosphate precipitate, it was found that only the L chi values were reliable, whereas the M chi values from the same lysosomal spectra were unrealistic, due to deconvolution problems in the computer programs applied. Based upon the L chi values it was found that among the population of lysosomes in single Kupffer cells, studied after a 60-min interval between the injection of the gold colloid and fixation, three types of lysosomal contents could be quantitated by X-ray microanalysis, viz. one type with only gold, one with only lead, one with gold and lead, in various ratios. This quantitative approach might make it possible to detect variations in lysosomal composition associated with ageing.

The dynamics of calcium phosphate precipitation studied with a new polyacrylamide steady state matrix-model: influence of pyrophosphate collagen and chondroitin sulfate

A novel steady-state gel-matrix model system is described which facilitates the quantitative kinetic study of the influence of media and matrix composition on a precipitation process. The potentialities of the system are illustrated in experiments in which the precipitation of calcium phosphate in a polyacrylamide film is studied as a function of the calcium and phosphate concentration in the solutions flowing along opposite sides of the film. Addition of pyrophosphate to the reactant solutions was found to diminish the (calcium) x (phosphate) millimolar product at which precipitation starts, indicating a positive effect on nucleation. The slope of the curve was found to decrease, which points to a negative influence of pyrophosphate on the crystal growth process. Incorporation of collagen in the matrix did not change the curve, but incorporation of chondroitin sulfate decreased the formation product since the intercept of the curve was reduced. The usefulness of the system compared with test-tube and non-steady state gel experiments for calcium phosphate precipitation studies and its significance for the study of in vitro and in vivo precipitation processes in general, are discussed.

Enzyme layers on glass as a new model for the quantitative study of capture reactions in cytochemistry, with special attention to acid phosphatase

A model system is described for the study of capture reactions for diffusable compounds in enzyme cytochemistry. The model, which allows the investigation of the influence of the composition of the cytochemical medium, the enzymatic activity, and the dimensions of the enzymatic site on the capture reaction, consists of very thin homogeneous layers of enzyme (0.01-0.1 micrometer thick) on glass, which are incubated in the cytochemical medium. The fraction of the total amount of liberated product precipitated in the enzyme layer is dependent not only on the trapping efficiency of the cytochemical medium but also on the concentration of the primary reaction product that can be built up in the enzyme layer. Calculations were performed to determine the steady-state concentration of the primary reaction product that can be built up in the enzyme layer. Acid phosphatase was used as enzyme. The problems associated with the model and its applicability to other types of cytochemical reactions are discussed.